1Crystal and molecular structure of three biologically active nitroindazoles - 副本

合集下载

The Properties of Crystals and Crystal Structures

The Properties of Crystals and CrystalStructuresCrystal structures have always fascinated science lovers and researchers alike. The beautiful and intricate patterns that crystals exhibit are not just aesthetically pleasing; they also provide important information about the physical and chemical properties of the crystals themselves. In this article, we will explore the properties of crystals and crystal structures and how they impact various scientific fields.What are crystals?Crystals are solids that have highly ordered structures, meaning that their atoms or molecules are arranged in a repeating pattern. This pattern is what gives crystals their characteristic geometric shape. Crystals can be formed from a wide variety of materials, including minerals, metals, and organic compounds.One of the defining features of crystals is that they have repeating units called unit cells. The unit cell is the smallest part of a crystal that still exhibits the same structural pattern as the whole crystal. By analyzing the unit cell, scientists can determine the basic structure of a crystal.What are the properties of crystals?One of the most important properties of crystals is their symmetry. Because crystals have an ordered structure, their symmetry is also highly organized. This symmetry is what gives crystals their characteristic shapes and also affects their physical properties, such as their melting point and conductivity.Another important property of crystals is their cleavage. Cleavage refers to the way in which a crystal breaks along certain planes. This property is determined by the arrangement of atoms within the crystal structure and can be used to identify different types of crystals.Crystal structures and their importance in scienceCrystal structures play an important role in various scientific fields, including chemistry, physics, and materials science. By understanding the structure of crystals, scientists can predict their physical and chemical properties, which can be used to develop new materials for various applications.For example, the development of new drugs often relies on an understanding of the crystal structure of the active ingredient. By analyzing the crystal structure, scientists can determine how the drug interacts with its targets and how it can be modified to increase its effectiveness.Crystal structures are also important in the field of materials science. By studying the crystal structure of materials, scientists can determine their mechanical and electrical properties. This information can be used to develop new materials with specific properties, such as advanced ceramics for use in electronics or stronger metals for use in aerospace applications.ConclusionIn conclusion, crystals and crystal structures are fascinating objects that provide important information about the physical and chemical properties of materials. The highly ordered structure of crystals gives them unique properties that can be harnessed for a variety of scientific and practical applications. By continuing to study crystals and their structures, scientists can unlock new insights into the world around us and develop new materials that will shape our future.。

天然姜黄素的纯化和分子与晶体结构研究(2)

早在１８１５年姜黄素就被从姜黄中分离出来，从此
以后，姜黄素和类姜黄素的结构表征及合成方面的报道陆续出现［３，４］。国内外有关姜黄的研究一直十分活跃，研究内容主要涉及姜黄药用活性成分及有效成分的提取、分离、分析、检测和结构鉴定，姜黄素及其衍生物的化学反应及药用功能研究等［５～７］。研究资料表明［８］，不同产地的姜黄一般具有不同的化学成分及组成；那么，从不同产地的姜黄中提取出的姜黄素是否有同样的分子与晶体结构？本文的工作证实，分子与晶体结构基本相同，但是结构数据有些差异。国内外对于天然姜黄素分子与晶体结构的研究报道较少［９，１０］，因此本文在天然姜黄素的纯化、谱学表征和分子与晶体测定方面的工作
Ｃ２１Ｈ２０Ｏ６３６８．３７２９３（２）Ｋ０．０７１０７３ｎｍＭｏｎｏｃｌｉｎｉｃ，Ｐ２／ｎａ＝１．２６９５（３）ｎｍ α＝９０° ｂ＝０．７２０７５（１６）ｎｍ β＝９５．０９８（４）° ｃ＝１．９９６０（４）ｎｍ γ＝９０° １．８１９１（７）ｎｍ３
（１．ＣｏｌｌｅｇｅｏｆＣｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＩｎｎｅｒＭｏｎｇｏｌｉａＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙ，Ｈｏｈｈｏｔ０１００６２，Ｃｈｉｎａ；２．ＣｏｌｌｅｇｅｏｆＣｈｅｍｉｃａｌａｎｄＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃｅ，ＩｎｎｅｒＭｏｎｇｏｌｉａＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ，Ｈｏｈｈｏｔ０１００２２，Ｃｈｉｎａ；
ＦＴＩＲ光谱在ＮｉｃｏｌｅｔＦＴ－ＩＲ光谱仪上测定，ＫＢｒ压片；ＵＶ－Ｖｉｓ光谱在ＳｈｉｍａｄｚｕＵＶ－３１０１光谱仪上记录；１ＨＮＭＲ和１３ＣＮＭＲ光谱在ＪＥＯ－ＪＮＭ－ＡＬ－３００ＦＴＮＭＲ仪上测定，ＴＭＳ作内标，ＣＤＣｌ３作溶剂；ＭＳ谱在Ｆｉｎｎｉｇａｎ－ＰｌｏａｒｉｓＱ－ＭＳ质谱仪上记录；利用ＳＧＷＸ－４型熔点仪测定天然姜黄素的熔点。１．２姜黄素的提取、纯化及谱学表征数据

Crystal Structure and the Paraelectric-to-Ferroelectric Phase Transition of Nanoscale BaTiO3

Crystal Structure and the Paraelectric-to-Ferroelectric PhaseTransition of Nanoscale BaTiO3Millicent B.Smith,†Katharine Page,‡Theo Siegrist,§Peter L.Redmond,†Erich C.Walter,†Ram Seshadri,‡Louis E.Brus,†and Michael L.Steigerwald*,†Department of Chemistry,Columbia Uni V ersity,3000Broadway,New York,New York10027,Materials Department and Materials Research Laboratory,Uni V ersity of California,Santa Barbara,California93106,and Bell Laboratories,600Mountain A V enue,Murray Hill,New Jersey07974Received August3,2007;E-mail:mls2064@Abstract:We have investigated the paraelectric-to-ferroelectric phase transition of various sizes ofnanocrystalline barium titanate(BaTiO3)by using temperature-dependent Raman spectroscopy and powderX-ray diffraction(XRD).Synchrotron X-ray scattering has been used to elucidate the room temperaturestructures of particles of different sizes by using both Rietveld reﬁnement and pair distribution function(PDF)analysis.We observe the ferroelectric tetragonal phase even for the smallest particles at26nm.Byusing temperature-dependent Raman spectroscopy and XRD,weﬁnd that the phase transition is diffusein temperature for the smaller particles,in contrast to the sharp transition that is found for the bulk sample.However,the actual transition temperature is almost unchanged.Rietveld and PDF analyses suggestincreased distortions with decreasing particle size,albeit in conjunction with a tendency to a cubic averagestructure.These results suggest that although structural distortions are robust to changes in particle size,what is affected is the coherency of the distortions,which is decreased in the smaller particles.IntroductionBarium titanate(BaTiO3)is a ferroelectric oxide that under-goes a transition from a ferroelectric tetragonal phase to aparaelectric cubic phase upon heating above130°C.In cubicperovskite BaTiO3,the structure of which is displayed in Figure1a,titanium atoms are octahedrally coordinated by six oxygenatoms.Ferroelectricity in tetragonal BaTiO3is due to an averagerelative displacement along the c-axis of titanium from itscentrosymmetric position in the unit cell and consequently thecreation of a permanent electric dipole.The tetragonal unit cellis shown in Figure1b.The elongation of the unit cell along thec-axis and consequently the deviation of the c/a ratio from unityare used as an indication of the presence of the ferroelectricphase.1–3Ferroelectric properties and a high dielectric constant make BaTiO3useful in an array of applications such as multilayer ceramic capacitors,4,5gate dielectrics,6waveguide modulators,7,8IR detectors,9and holographic memory.10The dielectric and ferroelectric properties of BaTiO3are known to correlate with size,and the technological trend toward decreasing dimensions makes it of interest to examine this correlation when sizes are at the nanoscale.11–16†Columbia University.‡University of California.§Bell Laboratories.(1)Jaffe,B.;Cook,W.R.;Jaffe,H.Piezoelectric Ceramics,Vol.3;Academic Press:New York,1971.(2)Lines,M.E.;Glass,A.M.Principles and Applications of Ferroelec-trics and Related Materials;Clarendon Press:Oxford,1977.(3)Strukov,B.A.;Levanyuk,A.P.Ferroelectric Phenomena in Crystals;Springer-Verlag:Berlin,1998.(4)Wang,S.F.;Dayton,G.O.J.Am.Ceram.Soc.1999,82,2677–2682.(5)Hennings,D.;Klee,M.;Waser,R.Ad V.Mater.1991,3,334–340.(6)Yildirim,F.A.;Ucurum,C.;Schliewe,R.R.;Bauhofer,W.;Meixner,R.M.;Goebel,H.;Krautschneider,W.Appl.Phys.Lett.2007,90, 083501/1–083501/3.(7)Tang,P.;Towner,D.J.;Meier,A.L.;Wessels,B.W.IEEE PhotonicTech.Lett.2004,16,1837–1839.(8)Petraru,A.;Schubert,J.;Schmid,M.;Buchal,C.Appl.Phys.Lett.2002,81,1375–1377.(9)Pevtsov,E.P.;Elkin,E.G.;Pospelova,M.A.Proc.SPIE-Int.Soc.Opt.Am.,1997,3200,179-182.(10)Funakoshi,H.;Okamoto,A.;Sato,K.J.Mod.Opt.2005,52,1511–1527.(11)Shaw,T.M.;Trolier-McKinstry,S.;McIntyre,P.C.Annu.Re V.Mater.Sci.2000,30,263–298.(12)Frey,M.H.;Payne,D.A.Phys.Re V.B1996,54,3158–3168.(13)Zhao,Z.;Buscaglia,V.;Vivani,M.;Buscaglia,M.T.;Mitoseriu,L.;Testino,A.;Nygren,M.;Johnsson,M.;Nanni,P.Phys.Re V.B2004, 70,024107.(14)Buscaglia,V.;Buscaglia,M.T.;Vivani,M.;Mitoseriu,L.;Nanni,P.;Terﬁletti,V.;Piaggio,P.;Gregora,I.;Ostapchuk,T.;Pokorny,J.;Petzelt,J.J.Eur.Ceram.Soc.2006,26,2889–2898.Figure1.Unit cell of BaTiO3in both the(a)cubic Pm-3m structure and (b)tetragonal P4mm structure.In the tetragonal unit cell,atoms are displaced in the z-direction,and the cell is elongated along the c-axis.Atom positions: Ba at(0,0,0);Ti at(1/2,1/2,z);O1at(1/2,1/2,z);and O2at(1/2,0,z). Displacements have been exaggerated forclarity.Published on Web05/08/200810.1021/ja0758436CCC:$40.75 2008American Chemical Society J.AM.CHEM.SOC.2008,130,6955–696396955Many experimental and theoretical17–25studies have indicated that the phase-transition temperature of BaTiO3is size-depend-ent,with the ferroelectric phase becoming unstable at room temperature when particle diameter decreases below a critical size.However,both theoretical and experimental reports of this critical size encompass a broad range of sizes.The experimental discrepancies may arise because of intrinsic differences between ferroelectric samples,because the transition is sensitive to conditions such as compositional variation,26lattice defects,12 strain,27or surface charges.20Furthermore,the differences in cell parameters between the two phases are small compared to other sources of broadening in diffraction data,likely leading to an overestimation of the critical size.Recent work by Fong et al.on perovskite(PbTiO3)thinﬁlms indicates that ferroelec-tric behavior persists down to a thickness of only three unit cells,25a value signiﬁcantly less than that suggested by previous experimental studies.Several theoretical studies have been particularly useful in furthering the understanding of the observed behavior of ferroelectrics at small sizes.17However,ferroelectrics are particularly sensitive to surface effects,making modeling increasingly complicated as dimensions are reduced.Many models based on Landau theory18overestimate critical sizes;it has been suggested that this overestimation has resulted from the use of material parameters in the free-energy expression that were derived from the bulk material.19Spanier et al.have found by theoretical modeling that certain surface termination of thin ﬁlms can stabilize polarization down to a thickness of only several unit cells.20Their calculations,which take into account experimentally determined nanoscale material parameters,es-timate the critical size for a BaTiO3sphere to be4.2nm.Other theoretical treatments,such as effective Hamiltonian and ab initio calculations,have predicted the presence of ferroelectricity in perovskiteﬁlms as thin as three unit cells.23,24Various experimental probes of the structure of BaTiO3have revealed a complex and sometimes controversial picture.In the study of bulk material,structural transformations have been explained by averaging domains that are locally rhombo-hedral.28,29For the tetragonal phase,the titanium atoms are distorted in the〈111〉directions and oriented with a net displacement in the c-direction.A number of studies have reported evidence of disorder within BaTiO3above the transition temperature,supporting the existence of distortions within the cubic phase.30–32X-ray diffraction(XRD)studies produce data that are consistent with an increasingly cubic structure at smaller particle sizes,not distinguishing between average and local structure.12,33In contrast,Raman results have supported the existence of tetragonal symmetry at small dimensions,even though it was not discernible by XRD.34The disagreement between Raman and diffraction studies suggests that the phase transition in bulk BaTiO3is complex,with order-disorder as well as displacive character.12,35,36Extended X-ray absorptionﬁne structure(EXAFS)and X-ray absorption near-edge structure(XANES)studies of bulk BaTiO3 have supported a dominant order-disorder component to the structural phase transitions.29In EXAFS and XANES analysis of10,35,and70nm BaTiO3particles,37Frenkel et al.ﬁnd titanium displacements for all samples studied,in contrast to their cubic macroscopic crystal structures from laboratory XRD. Petkov et al.38have recently demonstrated the use of the pair distribution function(PDF)to understand local structure distor-tions and polar behavior in Ba x Sr1-x TiO3(x)1,0.5,0) nanocrystals.They found that locally,reﬁning over theﬁrst15Å,the tetragonal model was the bestﬁt to the experimental PDF;however,over longer distances(15-28Å),the cubic model was the bestﬁt.Their conclusion was that5nm BaTiO3 is on average cubic,but that tetragonal-type distortions in the Ti-O distances are present within the cubic structure.They did not,however,ﬁnd the distortions to be inherent to small particles because they were not present in the perovskite SrTiO3. Several preparation strategies have been reported in recent years for high-quality,well-deﬁned BaTiO3nanocrystalline samples.Hydrothermal or solvothermal methods have been systematically used to make nanocrystalline BaTiO3.39–42O’Brien et al.43and Urban et al.21,44have produced BaTiO3particles and rods,respectively,from the reaction of a bimetallic alkoxide precursor with hydrogen peroxide.Niederberger et al.report a solvothermal preparation of5nm particles of BaTiO3and(15)Hoshina,T.;Kakemoto,H.;Tsurumi,T.;Wada,S.;Yashima,M.J.Appl.Phys.2006,99,054311–054318.(16)Yashima,M.;Hoshina,T.;Ishimura,D.;Kobayashi,S.;Nakamura,W.;Tsurumi,T.;Wada,S.J.Appl.Phys.2005,98,014313. (17)Duan,W.;Liu,Z.-R.Curr.Opin.Solid State Mater.Sci.2006,10,40–51.(18)Wang,C.L.;Smith,S.R.P.J.Phys.:Condens.Matter1995,7163–7171.(19)Akdogan,E.K.;Safari,A.J.Appl.Phys.2007,101,064114.(20)Spanier,J.E.;Kolpak,A.M.;Urban,J.J.;Grinberg,I.;Ouyang,L.;Yun,W.S.;Rappe,A.M.;Park,H.Nano Lett.2006,6,735–739.(21)Urban,J.J.;Spanier,J.E.;Lian,O.Y.;Yun,W.S.;Park,H.Ad V.Mater.2003,15,423–426.(22)Urban,J.J.Synthesis and Characterization of Transition Metal Oxideand Chalcogenide Nanostructures.Ph.D.Dissertation,Harvard Uni-versity,Cambridge,MA,2004.(23)Ghosez,P.;Rabe,K.M.Appl.Phys.Lett.2000,76,2767–2769.(24)Meyer,B.;Vanderbilt,D.Phys.Re V.B2001,63,205426.(25)Fong,D.D.;Stephenson,G.B.;Streiffer,S.K.;Eastman,J.A.;Auciello,O.;Fuoss,P.H.;Thompson,C.Science2004,304,1650–1653.(26)Lee,S.;Liu,Z.-K.;Randall,C.A.J.Appl.Phys.2007,101,054119.(27)Choi,K.J.;Biegalski,M.;Li,Y.L.;Sharan,A.;Schubert,J.;Uecker,R.;Reiche,P.;Chen,Y.B.;Pan,X.Q.;Gopalan,V.;Chen,L.-Q.;Schlom,D.G.;Eom,C.B.Science2004,306,1005–1009. (28)Kwei,G.H.;Lawson,A.C.;Billinge,S.J.L.;Chong,S.-W.J.Phys.Chem.1993,97,2368–2377.(29)Ravel,B.;Stern,E.A.;Vedrinskii,R.I.;Kraizman,V.Ferroelectrics1998,206–207,407–430.(30)Zalar,B.;Laguta Valentin,V.;Blinc,R.Phys.Re V.Lett.2003,90,037601.(31)Lambert,M.;Comes,R.Solid State Commun.1968,6,715–719.(32)Comes,R.;Lambert,M.;Guinier,A.Acta Crystallogr.,Sect.A:Cryst.Phys.,Diffr.,Theor.Gen.Crystallogr.1970,26,244–254.(33)Wada,S.;Tsurumi,T.;Chikamori,H.;Noma,T.;Suzuki,T.J.Cryst.Growth2001,229,433–439.(34)El Marssi,M.;Le Marrec,F.;Lukyanchuk,I.A.;Karkut,M.G.J.Appl.Phys.2003,94,3307–3312.(35)Wada,S.;Suzuki,T.;Osada,M.;Kakihana,M.;Noma,T.Jpn.J.Appl.Phys.1998,37,5385–5393.(36)Noma,T.;Wada,S.;Yano,M.;Suzuki,T.Jpn.J.Appl.Phys.1996,80,5223–5233.(37)Frenkel,A.I.;Frey,M.H.;Payne,D.A.J.Synchrotron Radiat.1999,6,515–517.(38)Petkov,V.;Gateshki,M.;Niederberger,M.;Ren,Y.Chem.Mater.2006,18,814–821.(39)Jung,Y.-J.;Lim,D.-Y.;Nho,J.-S.;Cho,S.-B.;Riman,R.E.;Lee,B.W.J.Cryst.Growth2005,274,638–652.(40)Yosenick,T.;Miller,D.;Kumar,R.;Nelson,J.;Randall,C.;Adair,J.J.Mater.Res.2005,20,837–843.(41)Guangneng,F.;Lixia,H.;Xueguang,H.J.Cryst.Growth2005,279,489–493.(42)Joshi,U.A.;Yoon,S.;Baik,S.;Lee,J.S.J.Phys.Chem.B2006,110,12249–12256.(43)O’Brien,S.;Brus,L.;Murray,C.B.J.Am.Chem.Soc.2001,123,12085–12086.(44)Urban,J.J.;Yun,W.S.;Gu,Q.;Park,H.J.Am.Chem.Soc.2002,124,1186–1187.6956J.AM.CHEM.SOC.9VOL.130,NO.22,2008A R T I C L E S Smith et al.SrTiO3from titanium isopropoxide and metallic barium or strontium in benzyl alcohol.45Here,we describe the use of a bimetallic alkoxide precursor in conjunction with solvothermal techniques to produce high-quality nanoparticles of BaTiO3with controllable sizes.We have studied particles with average sizes of26,45,and70nm by temperature-dependent Raman spectroscopy and XRD and with room temperature Rietveld and atomic PDF analysis of high-energy,high momentum-transfer synchrotron X-ray diffraction data.The sample particles are unstrained,because they are not thin-ﬁlm samples and are compositionally homogeneous with, in particular,no discernible OH impurities that are known to plague many low-temperature solution preparations of ferro-electric oxides.12,33,36The complementary structural methods we employ provide information on different time and length scales.Raman spectra reﬂect the local symmetry around the scattering sites and are averaged over different parts of the sample.The X-ray techniques both allow an average depiction of the structure (through pattern matching and Rietveld analysis)and provide information on the near-neighbor length scale through PDF. The outcomes of the current study are consistent between the different techniques and are somewhat surprising.Raman spectroscopy indicates that the small particles undergo a more diffuse phase transition than in the bulk,although the T C remains nearly unchanged.Careful temperature-dependent XRD studies show that all sizes of particles are tetragonal until close to the bulk T C,and yet the smaller particles seem more cubic by using the c/a ratio as the metric.Average(Rietveld)and local(PDF) structure analyses of X-ray synchrotron data show that as the particle size is reduced,there is a clear and surprising trend toward increasing structural distortion.The increase in the off-centering of the titanium cation as particle size decreases in conjunction with the decrease in the c/a ratios is consistent with diminished structural coherence in smaller particles. Experimental SectionPreparation of BaTiO3Nanoparticles.Anhydrous benzene, isopropanol,dendritic barium(99.99%),and titanium isopropoxide (99.999%)were obtained from Aldrich Chemical Co.and used as received.Sintered pieces of BaTiO3were also purchased from Aldrich for use as a bulk standard.The bimetallic precursor BaTi[OC3H7]6was prepared according to Urban et al.44Parr acid digestion bombs with23mL Teﬂon liners were used for the solvothermal reaction.In a typical synthesis,10mmol(5.4g)of the precursor,BaTi[OC3H7]6,was added to the Teﬂon liner of a digestion bomb under an inert atmosphere.A total of10mL of solvent was added to the precursor underﬂowing argon according to the water and isopropanol ratios in Table1.In none of the solvents used did the precursor dissolve,but rather it formed a thick white suspension.The Teﬂon liner was tightly sealed inside the acid digestion bomb,and the mixture was heated in an oven at 220°C for18h.The resulting white precipitate was collected by centrifugation,washed with ethanol,and allowed to dry underambient conditions.A white powder suitable for powder XRD andRaman measurements was produced with a typical yield of1.93g.Transmission electron microscope(TEM)images were taken on aJEOL100CX instrument by using an accelerating voltage of100kV.Raman Spectroscopy.Raman spectroscopy was performed in air by using a backscattering micro-Raman spectrometer withhelium-neon laser(633nm)excitation.A home-built thermoelec-tric heating stage was used for temperature-dependent measure-ments.Spectra were taken at temperatures ranging from roomtemperature to above150°C.The300cm-1peak35wasﬁt to aLorentzian line shape on a sloping baseline,and from thisﬁt,thescaled peak area and linewidth were determined.Differential Scanning Calorimetry.Differential scanning cal-orimetry(DSC)was performed on a Perkin-Elmer Pyris1DSC.For each scan,3-4mg of sample was used.The heating proﬁleconsisted of two cycles of heating from0to150°C at a rate of10°C/min and then cooling from150to0°C at that same rate. Thermodiffraction.X-ray diffraction data were obtained by using a Rigaku rotating anode together with a custom-built four-circle diffractometer.Graphite monochromated Cu K radiation(1.39217Å),together with a matched graphite analyzer,was usedin Bragg-Brentano geometry.In this way,a well-deﬁned powderdiffraction proﬁle was obtained for all reﬂections,allowing adetailed analysis of the proﬁle changes associated with theparaelectric-to-ferroelectric phase transition.The intensities werenormalized to the incident beam to eliminate drift over the dataacquisition time.A home-built heating stage was used to reachtemperatures up to150°C.X-ray patterns above143°C werecollected to obtain a cubic reference for the expected increase inthe peak widths with2θ.Full pattern reﬁnements were executedin the program Winprep46by using the proﬁle parameters obtainedfrom the cubic phase above143°C.Synchrotron X-ray Diffraction.Synchrotron powder diffrac-tion data were collected in transmission mode at beamline11-ID-B of the Advanced Photon Source,Argonne National Laboratory,by utilizing high-energy X-rays(∼90kV)at room temperature.The use of high-energy X-rays enables measure-ments at longer wavevectors,Q)4πsin(θ/λ),which is important for the application of the PDF technique.Samples were loaded in Kapton tubes,and scattering data were collected on an image plate system(amorphous silicon detector from General Electric Healthcare)with sample-to-detector distances of660 mm for Rietveld reﬁnement data and150mm for PDF data. The raw data sets were processed to one-dimensional X-ray diffraction data by using the program FIT2D.47A bulk internal standard was used to calibrate the processed data,to supply an effective wavelength ofλ)0.13648Åfor reﬁnements.Rietveld reﬁnement of the synchrotron data was carried out in the XND program.48Lattice parameters,atomic positions,and atomic displacement parameters were reﬁned.The PDF,G(r))4πr[F(r)-F],was extracted from the processed scattering data asdescribed by Chupas et al.49with a maximum momentum transferof Q)24Å-1by using the program PDFGETX2.50In thisequation,F(r)is the local atomic number density,F0is theaverage atomic number density,and r is the radial distance.Fullstructure proﬁle reﬁnements were carried out in the programsPDFﬁt2and PDFgui.51The scale factor,lattice parameters,(45)Niederberger,M.;Garnweitner,G.;Pinna,N.;Antonietti,M.J.Am.Chem.Soc.2004,126,9120–9126.(46)Stahl,K.Winprep;Lyngby,Denmark.(47)Hammersley,A.P.;Svensson,S.O.;Hanﬂand,M.;Fitch,A.N.;Hausermann,D.High Pressure Res.1996,14,235–248.(48)Bèrar,J.F.;Garnier,P.NIST Spec.Publ.1992,846,212.(49)Chupas,P.J.;Qui,X.;Hanson,J.C.;Lee,P.L.;Grey,C.P.;Billinge,S.J.L.J.Appl.Crystallogr.2003,36,1342–1347.(50)Qiu,Y.;Wu,C.Q.;Nasu,K.Phys.Re V.B2005,72,224105-1–224105-7.(51)Farrow,C.L.;Thompson,J.W.;Billinge,S.J.L.J.Appl.Crystallogr.2004,37,678.Table1.Particle Size Dependence on Solvent Compositionwater:isopropanol(v:v)particle size(nm)1:070(1040:6060(1030:7045(920:8026(50:1∼10J.AM.CHEM.SOC.9VOL.130,NO.22,20086957 Paraelectric-to-Ferroelectric Phase Transition of Nanoscale BaTiO3A R T I C L E Satomic displacement parameters,and atomic positions as well as broadening from the sample and the instrument resolution were reﬁned.Results and DiscussionPreparation of BaTiO 3Nanoparticles.We explored the effectsof reaction conditions such as temperature,precursor concentra-tion,solvent composition,and addition of surfactants in the preparation of BaTiO 3nanoparticles.We found that the composition of the solvent played a critical role in determining the size of the particles,pure water producing the largest sizes and pure isopropanol producing the smallest.A TEM was used to determine the particle size and morphology,and typical images are shown in Figure 2,with histograms of the particle-size distributions displayed as insets.The particles were nearly spherical in shape with average sizes of 70,45,and 26nm.Table 1gives the average particle size obtained with each solvent mixture as determined by TEM;the given error is plusor minus one standard deviation.Scherrer analysis 52of the laboratory XRD (111)peak at room temperature gave X-ray coherence lengths (grain sizes)of 33,29,and 21nm for the 70,45and 26nm particles,respectively.The instrumental line width limits the determination of particle size to a maximum of 35nm,preventing any conclusions about the single crystal-linity (grain size)of the 70nm particles.However,for the two smaller sizes,the individual particles are likely single crystals.The ﬁnal size of the particles is determined by the balance between particle nucleation and growth.In order to form BaTiO 3from the alkoxide precursor,M -O -M bonds must be formed from M -OR species (M )Ti,Ba;R )-OC 3H 7).In the mixed solvent system,it is likely that several mechanisms are in competition with one another,determining the reaction pathway.In pure water,the pH of the solvent -precursor solution was 13,suggesting the partial hydrolysis of the precursor to Ba(OH)2.This M -OH species can react with a second M -OH or with an M -OR to form the M -O -M bonds and water or isopro-panol,respectively.M -O -M bonds might also form through a -hydride elimination and the reaction of the metal hydride with an M -OR.An additional effect of the solvent composition is that the isopropyl group is a better capping group than the hydroxide because -OC 3H 7is less reactive than -OH.Isopro-poxy moieties on the surface of a particle passivate the surface,inhibiting particle growth and leading to smaller particle sizes.Raman Spectroscopy.Tetragonal BaTiO 3has 10Raman-active modes.When splitting of transverse and longitudinal optical modes,as well as splitting due to differing polarizability in each unit cell direction is considered,18Raman-active phonons result.53Symmetry demands that cubic BaTiO 3should be completely Raman-inactive.However,broad peaks centered at 260and 530cm -1are still observed above the cubic-to-tetragonal phase-transition temperature.34The Raman activity of the cubic phase has been generally attributed in the literature to disorder of titanium in the nominally cubic phase.53Figure 3shows the Raman spectrum of (a)bulk,(b)70nm,(c)45nm,and (d)26nm BaTiO 3over a range of temperatures between 25and 150°C.The assignments given to the Raman modes at the top of Figure 3are those reported in the literature.34Below 200cm -1,we ﬁnd some weak scattering in the nanoparticle samples due to a BaCO 3impurity.As seen by others,the BaTiO 3Raman spectra have the broad features characteristic of titanium disorder in the unit cell at all temperatures and at all sizes.In the bulk BaTiO 3spectra in Figure 3a,the intensities of the E (LO +TO),B 1peaks at ∼300cm -1and E (LO),A 1(LO)peaks at ∼715cm -1decrease rapidly as the temperature increases through the bulk T C ,an observation consistent with prior reports.35We interpret the disappearance of the 300cm -1peak as an indicator of the tetragonal phase and use two characteristics as an indication of the phase transition.The ﬁrst is an increase in peak width at the phase-transition temperature similar to that reported by Hoshina et al.,15and the second is the loss of peak intensity with increasing temperature.These values are given in Figure 4a -d.For all samples,the linewidth for the E (LO +TO),B 1peak increases both with increasing temperature and with decreasing particle size.The much larger linewidths of the Raman peaks of the nanoparticles suggest that the tetragonality present is accompanied by a signiﬁcantly decreased structural coherence.(52)Cullity,B.D.;Stock,S.R.Elements of X-ray Diffraction ,3rd ed.;Prentice Hall:Upper Saddle River,NJ,2001.(53)DiDomenico,M.;Wemple,S.H.;Porto,S.P.S.Phys.Re V .1968,174,522–530.Figure 2.TEM images of BaTiO 3nanoparticles.Histograms of individualparticle sizes,shown as insets,correspond to (a)70(10nm,(b)45(9nm,and (c)26(5nm.The 200nm scale bar is common to all three micrographs.6958J.AM.CHEM.SOC.9VOL.130,NO.22,2008A R T I C L E S Smith et al.It is interesting to note that bulk BaTiO 3near the cubic-to-tetragonal phase transition displays a Raman linewidth that is similar to the line width displayed by the 26nm particles at all temperatures.The linewidth analysis is complemented by the analysis of scaled peak area.Figure 4shows that near the expected phase-transition temperature of 130°C,there is a sharp drop in the Raman intensity of the 300cm -1peak for the bulk sample but a more gradual decrease in intensity over the entire temperature range for the 70and 45nm particles.In contrast,the peak area of the 26nm particles in Figure 4d is nearly constant over the entire temperature range.These results indicate a phase transition that becomes increasingly diffuse in temperature as the particle size decreases.The lack of a sharply deﬁned phase transition in nanosized samples is also observed by using DSC.For bulk BaTiO 3,the DSC trace exhibits a peak near 130°C,indicative of the phase transition.Similar features are not observed in the DSC of nanoparticle samples.Together with the Raman results,these ﬁndings support the idea that the phase transition is distributed over a wide range of temperatures in the nanoparticles,although it is sharply deﬁned in the bulk material.Thermodiffraction.The splitting of the X-ray diffraction peaks is well deﬁned in terms of symmetry,allowing analysis of systematic changes for different (hkl )indices.Figure 5shows diffraction data for 70nm BaTiO 3at room temperature and at 148°C over a small 2θrange.In the high-symmetry cubic phase,no reﬂections are split.In the tetragonal phase,(222)remains a single peak whereas the (400)reﬂection is divided into (400/040)and (004)peaks with an intensity ratio of 2:1.Because the c /a ratio is larger than 1,the (004)reﬂection shifts to a lower 2θvalue,and the (400/040)reﬂection correspondingly shifts to a higher 2θvalue.In spite of changes in symmetry,the cubic-to-tetragonal phase transition is usually not well resolved in diffraction studies of nanosized BaTiO 3because of inherent line broadening due to small particle size.In our study,the phase evolution of BaTiO 3particles was determined by pattern matching to the laboratory X-raydif-Figure 3.Raman spectra at different temperatures for (a)bulk BaTiO 3,(b)70nm particles,(c)45nm particles,and (d)26nm particles.Temperatures increase from top to bottom in each panel.Temperatures are speciﬁed to be within a range of up to (3°C.The locations of Raman modes are indicated at the top of the ﬁgure.The features below 200cm -1are due to a trace BaCO 3impurity,and these are not found in the bulksample.Figure 4.Results from ﬁts to the Raman data.Filled circles show variationof the linewidth of the 300cm -1Raman signal as a function of temperature.Open squares are intensities of the 300cm -1Raman signal normalized to the intensity at 280cm -1.Displayed for (a)bulk powder,(b)70nm particles,(c)45nm particles,and (d)26nmparticles.Figure 5.70nm BaTiO 3particle laboratory XRD data shown over a small 2θrange.(a)Recorded at room temperature.(b)Recorded at 148°C.Reﬂections have been labeled for the cubic phase in panel b.The (222)peak does not split in the tetragonal phase,and consequently,the peak width is constant with temperature.Peaks which are degenerate in the cubic phase but not in the tetragonal phase,for example cubic (400),widen and lose intensity upon cooling.J.AM.CHEM.SOC.9VOL.130,NO.22,20086959Paraelectric-to-Ferroelectric Phase Transition of Nanoscale BaTiO 3A R T I C L E S。

第 6 届 HChO 化学竞赛联考试题试题、答案、评分标准、细则

第6届H C h O化学竞赛联考试题、答案、评分标准、细则与参考文献评分通则1.凡要求计算或推导的，须示出计算或推导过程。

无计算或推导过程，即使最终结果正确也不得分。

2.有效数字错误，扣0.5分，但每一大题只扣1次。

3.单位不写或表达错误，扣0.5分，但每一大题只扣1次。

4.只要求1个答案、而给出多个答案, 其中有错误的，不得分。

5.方程式不配平不得分，画等号或单前头皆可。

6.用铅笔解答的部分（包括作图）无效。

7.用涂改液或修正带修改，整个答卷无效。

8.考生信息必须写在答卷首页左侧指定位置，写于其他地方按废卷论处。

9.写有与试题无关的任何文字的答卷均作废。

10.不包括在标准答案的0.5分的题，无法决定是否给分的，欢迎与我本人探讨！第1题(8分) 二硫化碳，CS2，是一种无色透明易挥发的液体，也是一种常用的溶剂。

1-1 由于CS2是一种吸热化合物，因此它具有较高的反应活性。

正因如此它对脑部可产生不可逆的损伤。

工业上采用高温下氧化铝催化CH4(g)与S(s)的混合物反应来制备CS2(g)。

1-1-1写出此反应的方程式。

1-1-2计算此反应的反应热。

已知：(1) C(s) + 2H2(g) → CH4(g) ΔH1 = -74.8 kJ mol-1(2) C(s) + 2S(s) → CS2(g) ΔH2 = +117.4 kJ mol-1Ө-26Ө22量地形成双二硫代碳酸乙酯：以淀粉为指示剂，0.2000 g 含有惰性杂质的CS2样品将消耗0.04584 mol·L-1 I2 27.37 mL。

未加入样品的乙醇在同样条件下滴加了0.21 mL I2标准溶液方到达终点。

计算样品中CS2的含量。

第2题(11分)2-1KMgPO4·6H2O中存在接近于孤立的钾离子，每1mol此晶体中存在多少mol的氢键？2-1 12mol 2分，参考图形：2-2 写出中性条件（无外加缓冲体系）下KMnO4分别氧化KHC2O4和K2C2O4的反应，并指223223通过测量与计算，此分子的结构得以确定。

胆甾相液晶的光学特性_李昌立

第17卷　第3期2002年6月液　晶　与　显　示Chinese Journal of Liquid Crystals and Displays Vol .17,No .3　Jun .,2002文章编号:1007-2780(2002)03-0193-06胆甾相液晶的光学特性李昌立,孙　晶,蔡红星,翁占坤,高俊杰(长春光学精密机械学院,吉林长春　130022)摘　要:基于胆甾相液晶的特殊分子结构,综合阐述了胆甾相液晶的旋光性、选择性光散射和偏振光二色性等光学特性,揭示了它的光学特性主要源于它螺旋状的分子结构及其光学各相异性。

关键词:胆甾相液晶;选择性光散射;螺距;布喇格反射中图分类号:O753.2 文献标识码:A 收稿日期:2001-12-02;修订日期:2001-12-261　引言胆甾相液晶同其他液晶态物质一样,既有液体的流动性、形变性、粘性,又具有晶体的光学各向异性,是一种优良的非线性光学材料[1],具有明显的热光效应、电光效应、电热光效应[2]、磁光效应[3]、压光效应[4,5]等。

较一般液晶不同的是它具有螺旋状分子取向的排列结构,因此,它除了具有普通液晶具有的光学性质外还具有它本身特有的光学特性。

2　胆甾相液晶胆甾相液晶也称螺旋状液晶,是一种在一定温度范围内呈现液晶相的胆甾醇衍生物(酯化物或卤代物)以及分子内具有不对称碳原子的高分子化合物,它具有层状的分子排列结构,层与层间相互平行,其分子细长,长轴具有沿某一优先方向取向,相邻两层分子间的取向不同,一般相差15°左右,且该优先方向取向在空间沿螺旋轴(光轴方向)螺旋状旋转。

因此,各层间的取向渐变可连成一条空间扭曲的螺旋线,该液晶整体形成螺旋结构(如图1)。

设胆甾相液晶的优先方向(指向矢)为n ,螺距为p ,由于在液晶相中,胆甾相结构沿指向矢方向呈周期性变化,且n 和-n 具有等价性,所以,其螺距周期为p 2,其典型值约为0.3μm ,远远大于分子线度,为可见光波长数量级。

CrystGrowthDes晶体生长英文文献

An Inﬁnite Two-Dimensional Hybrid Water-Chloride Network,Self-Assembled in a Hydrophobic Terpyridine Iron(II)MatrixRicardo R.Fernandes,†Alexander M.Kirillov,†M.Fátima C.Guedes da Silva,†,‡Zhen Ma,†JoséA.L.da Silva,†João J.R.Fraústo da Silva,†andArmando J.L.Pombeiro*,†Centro de Química Estrutural,Complexo I,Instituto Superior Técnico,TU-Lisbon,A V.Ro V isco Pais,1049-001Lisbon,Portugal,and Uni V ersidade Luso´fona de Humanidades e Tecnologias,A V.doCampo Grande,376,1749-024,Lisbon,PortugalRecei V ed October18,2007;Re V ised Manuscript Recei V ed January7,2008ABSTRACT:An unprecedented two-dimensional water-chloride anionic{[(H2O)20(Cl)4]4–}n network has been structurally identiﬁed in a hydrophobic matrix of the iron(II)compound[FeL2]Cl2·10H2O(L)4′-phenyl-2,2′:6′,2″-terpyridine).Its intricate relief geometry has been described as a set of10nonequivalent alternating cycles of different sizes ranging from tetra-to octanuclear{[(H2O)x(Cl)y]y–}z(x) 2–6,y)0–2,z)4–6,8)fragments.In contrast to the blooming research on structural characterizationof a wide variety of water clusters in different crystalline materials,1much less attention has been focused on the identiﬁcation anddescription of hybrid hydrogen-bonded water assemblies with othersolvents,small molecules,or counterions.1c,2In particular,thecombination of chloride ions and water is one of the most commonlyfound in natural environments(e.g.,seawater or sea-salt aerosols),and thus the investigation of water-chloride interactions has beenthe object of numerous theoretical studies.3However,only recentlya few water-chloride associates incorporated in various crystalmatrixes have been identiﬁed and structurally characterized,4,5including examples of(i)discrete cyclic[(H2O)4(Cl)]–,4a[(H2O)4(Cl)2]2–,4b and[(H2O)6(Cl)2]2–4c clusters,and(ii)variousone-or two-dimensional(1D or2D)hydrogen-bonded networksgenerated from crystallization water and chloride counterionswith{[(H2O)4(Cl2)]2–}n,5b{[(H2O)6(Cl)2]2–}n,5b[(H2O)7(HCl)2]n,5c{[(H2O)11(Cl)7]7–}n,5d{[(H2O)14(Cl)2]2–}n,5e{[(H2O)14(Cl)4]4–}n,5aand{[(H2O)14(Cl)5]5–}n5f compositions.These studies are alsobelieved to provide a contribution toward the understanding of thehydration phenomena of chloride ions in nature and have importancein biochemistry,catalysis,supramolecular chemistry,and designof crystalline materials.5In pursuit of our interest in the self-assembly synthesis andcrystallization of various transition metal compounds in aqueousmedia,we have recently described the[(H2O)10]n,6a(H2O)6,6b and[(H2O)4(Cl)2]2–4b clusters hosted by Cu/Na or Ni metal-organicmatrixes.Continuing this research,we report herein the isolationand structural characterization of a unique2D water-chlorideanionic layer{[(H2O)20(Cl)4]4–}n within the crystal structure of thebis-terpyridine iron(II)compound[FeL2]Cl2·10H2O(1′)(L)4′-phenyl-2,2′:6′,2″-terpyridine).Although this compound has beenobtained unexpectedly,a search in the Cambridge StructuralDatabase(CSD)7,8points out that various terpyridine containinghosts tend to stabilize water-chloride associates,thus also sup-porting the recognized ability of terpyridine ligands in supra-molecular chemistry and crystal engineering.9,10Hence,the simple combination of FeCl2·2H2O and L in tetrahydrofuran(THF)solution at room temperature provides the formation of a deep purple solid formulated as[FeL2]Cl2·FeCl2·5H2O(1)on the basis of elemental analysis,FAB+-MS and IR spectroscopy.11This compound reveals a high afﬁnity for water and,upon recrystallization from a MeOH/H2O(v/v)9/1)mixture,leads to single crystals of1′with a higher water content,which have been characterized by single-crystal X-ray analysis.12The asymmetric unit of1′is composed of a cationic[FeL2]2+ part,two chloride anions,and10independent crystallization water molecules(with all their H atoms located in the difference Fourier map),the latter occupying a considerable portion of the crystal cell. The iron atom possesses a signiﬁcantly distorted octahedral coordination environmentﬁlled by two tridentate terpyridine moieties arranged in a nearly perpendicular fashion(Figure S1, Supporting Information).Most of the bonding parameters within [FeL2]2+are comparable to those reported for other iron compounds*To whom correspondence should be sent.Fax:+351-21-8464455.E-mail: pombeiro@ist.utl.pt.†Instituto Superior Técnico.‡Universidade Luso´fona de Humanidades eTecnologias.Figure 1.Perspective representations(arbitrary views)of hybrid water-chloride hydrogen-bonded assemblies in the crystal cell of1′; H2O molecules and chloride ions are shown as colored sticks and balls, respectively.(a)Minimal repeating{[(H2O)20(Cl)4]4–}n fragment with atom numbering scheme.(b)Nonplanar inﬁnite polycyclic2D anionic layer generated by linkage of four{[(H2O)20(Cl)4]4–}n fragments(a) represented by different colors;the numbers are those of Table1and deﬁne the10nonequivalent alternating cycles of different size.2008310.1021/cg7010315CCC:$40.75 2008American Chemical SocietyPublished on Web02/08/2008bearing two terpyridine ligands.13The most interesting feature of the crystal structure of 1′consists in the extensive hydrogen bonding interactions of all the lattice–water molecules and chloride coun-terions (Table S1,Supporting Information),leading to the formation of a hybrid water -chloride polymeric assembly possessing minimal repeating {[(H 2O)20(Cl)4]4–}n fragments (Figure 1a).These are further interlinked by hydrogen bonds generating a nonplanar 2D water -chloride anionic layer (Figure 1b).Hence,the multicyclic {[(H 2O)20(Cl)4]4–}n fragment is con-structed by means of 12nonequivalent O–H ···O interactions with O ···O distances ranging from 2.727to 2.914Åand eight O–H ···Cl hydrogen bonds with O ···Cl separations varying in the 3.178–3.234Årange (Table S1,Supporting Information).Both average O ···O [∼2.82Å]and O ···Cl [∼3.20Å]separations are comparable to those found in liquid water (i.e.,2.85Å)14and various types of H 2O clusters 1,6or hybrid H 2O -Cl associates.4,5Eight of ten water molecules participate in the formation of three hydrogen bonds each (donating two and accepting one hydrogen),while the O3and O7H 2O molecules along with both Cl1and Cl2ions are involved in four hydrogen-bonding contacts.The resulting 2D network can be considered as a set of alternating cyclic fragments (Figure 1b)which are classiﬁed in Table 1and additionally shown by different colors in Figure 2.Altogether there are 10different cycles,that is,ﬁve tetranuclear,three pentanuclear,one hexanuclear,and one octa-nuclear fragment (Figures 1b and 2,Table 1).Three of them (cycles 1,2,and 6)are composed of only water molecules,whereas the other seven rings are water -chloride hybrids with one or two Cl atoms.The most lengthy O ···O,O ···Cl,or Cl ···Cl nonbonding separations within rings vary from 4.28to 7.91Å(Table 1,cycles 1and 10,respectively).Most of the cycles are nonplanar (except those derived from the three symmetry generated tetrameric fragments,cycles 1,2,and 4),thus contributing to the formation of an intricate relief geometry of the water -chloride layer,possessing average O ···O ···O,O ···Cl ···O,and O ···O ···Cl angles of ca.104.9,105.9,and 114.6°,respectively (Table S2,Supporting Information).The unprecedented character of thewater -chloride assembly in 1′has been conﬁrmed by a thorough search in the CSD,7,15since the manual analysis of 156potentially signiﬁcant entries with the minimal [(H 2O)3(Cl)]–core obtained within the searching algorithm 15did not match a similar topology.Nevertheless,we were able to ﬁnd several other interesting examples 16of inﬁnite 2D and three-dimensional (3D)water -chloride networks,most of them exhibiting strong interactions with metal -organic matrixes.The crystal packing diagram of 1′along the a axis (Figure 3)shows that 2D water -chloride anionic layers occupy the free space between hydrophobic arrays of metal -organic units,with an interlayer separation of 12.2125(13)Åthat is equivalent to the b unit cell dimension.12In contrast to most of the previously identiﬁed water clusters,1,6water -chloride networks,5,16and extended assemblies,1c the incorporation of {[(H 2O)20(Cl)4]4–}n sheets in 1′is not supported by strong intermolecular interactions with the terpyridine iron matrix.Nevertheless,four weak C–H ···O hydrogen bonds [avg d (D ···A))3.39Å]between some terpyridine CH atoms and lattice–water molecules (Table S1,Figure S2,Supporting Information)lead to the formation of a 3D supramolecular framework.The thermal gravimetric analysis (combined TG-DSC)of 117(Figure S3,Supporting Information)shows the stepwise elimination of lattice–water in the broad 50–305°C temperature interval,in accord with the detection on the differential scanning calorimetryTable 1.Description of Cyclic Fragments within the {[(H 2O)20(Cl)4]4–}n Network in 1′entry/cycle numbernumber of O/Cl atomsformula atom numberingschemegeometry most lengthy separation,Åcolor code a 14(H 2O)4O3–O4–O3–O4planar O3···O3,4.28light brown 24(H 2O)4O6–O7–O6–O7planar O7···O7,4.42light gray 34[(H 2O)3(Cl)]-O2–O4–O3–Cl2nonplanar O4···Cl2,4.66blue 44[(H 2O)3(Cl)]-O6–O7–O9–Cl1nonplanar O7···Cl1,4.61green 54[(H 2O)2(Cl)2]2-O9–Cl1–O9–Cl1planar Cl ···Cl1,4.76pink 65(H 2O)5O2–O4–O3–O10–O8nonplanar O2···O10,4.55red75[(H 2O)4(Cl)]-O1–O5–O7–O9–Cl1nonplanar O7···Cl1,5.25pale yellow 85[(H 2O)4(Cl)]-O1–O5–Cl2–O8–O10nonplanar O10···Cl2,5.29orange 96[(H 2O)4(Cl)2]2-O2–O8–Cl2–O2–O8–Cl2nonplanar Cl2···Cl2,7.12yellow 108[(H 2O)6(Cl)2]2-O1–O10–O3–Cl2–O5–O7–O6–Cl1nonplanarCl1···Cl2,7.91pale blueaColor codes are those of Figure 2.Figure 2.Fragment of nonplanar inﬁnite polycyclic 2D anionic layer in the crystal cell of 1′.The 10nonequivalent alternating water or water -chloride cycles are shown by different colors (see Table 1for color codes).Figure 3.Fragment of the crystal packing diagram of 1′along the a axis showing the intercalation of two water -chloride layers (represented by space ﬁlling model)into the metal -organic matrix (depicted as sticks);color codes within H 2O -Cl layers:O red,Cl green,H grey.Communications Crystal Growth &Design,Vol.8,No.3,2008783curve(DSC)of three major endothermic processes in ca.50–170, 170–200,and200–305°C ranges with maxima at ca.165,190, and280°C,corresponding to the stepwise loss of ca.two,one, and two H2O molecules,respectively(the overall mass loss of9.1% is in accord with the calculated value of9.4%for the elimination of allﬁve water molecules).In accord,the initial broad and intense IRν(H2O)andδ(H2O)bands of1(maxima at3462and1656cm–1, respectively)gradually decrease in intensity on heating the sample up to ca.305°C,while the other bands remain almost unchangeable. Further heating above305°C leads to the sequential decomposition of the bis-terpyridine iron unit.These observations have also been supported by the IR spectra of the products remaining after heating the sample at different temperatures.The elimination of the last portions of water in1at temperatures as high as250–305°C is not commonly observed(although it is not unprecedented18)for crystalline materials with hosted water clusters,and can be related to the presence and extensive hydrogen-bonding of chloride ions in the crystal cell,tending to form the O–H(water)···Cl hydrogen bonds ca.2.5times stronger in energy than the corresponding O–H(water)···O(water)ones.5a The strong binding of crystallization water in1is also conﬁrmed by its FAB+-MS analysis that reveals the rather uncommon formation of the fragments bearing from one toﬁve H2O molecules.11The exposure to water vapors for ca.8h of an almost completely dehydrated(as conﬁrmed by weighing and IR spectroscopy)product after thermolysis of1(at250°C19for 30min)results in the reabsorption of water molecules giving a material with weight and IR spectrum identical to those of the initial sample1,thus corroborating the reversibility of the water escape and binding process.In conclusion,we have synthesized and structurally characterized a new type of2D hybrid water-chloride anionic multicyclic {[(H2O)20(Cl)4]4–}n network self-assembled in a hydrophobic matrix of the bis-terpyridine iron(II)complex,that is,[FeL2]Cl2·10H2O 1′.On the basis of the recent description and detailed analysis of the related{[(H2O)14(Cl)4]4–}n layers5a and taking into consideration that the water-chloride assembly in1′does not possess strong interactions with the metal-organic units,the crystal structure of 1′can alternatively be deﬁned as an unusual set of water-chloride “hosts”with bis-terpyridine iron“guests”.Moreover,the present study extends the still limited number5of well-identiﬁed examples of large polymeric2D water-chloride assemblies intercalated in crystalline materials and shows that terpyridine compounds can provide rather suitable matrixes to stabilize and store water-chloride aggregates.Further work is currently in progress aiming at searching for possible applications in nanoelectrical devices,as well as understanding how the modiﬁcation of the terpyridine ligand or the replacement of chlorides by other counterions with a high accepting ability toward hydrogen-bonds can affect the type and topology of the hybrid water containing associates within various terpyridine transition metal complexes.Acknowledgment.This work has been partially supported by the Foundation for Science and Technology(FCT)and its POCI 2010programme(FEDER funded),and by a HRTM Marie Curie Research Training Network(AQUACHEM project,CMTN-CT-2003-503864).The authors gratefully acknowledge Prof.Maria Filipa Ribeiro for kindly running the TG-DSC analysis,urent Benisvy,Dr.Maximilian N.Kopylovich,and Mr.Yauhen Y. Karabach for helpful discussions.Supporting Information Available:Additionalﬁgures(Figures S1–S3)with structural fragments of1′and TG-DSC analysis of1, Tables S1and S2with hydrogen-bond geometry in1′and bond angles within the H2O-Cl network,details for the general experimental procedures and X-ray crystal structure analysis and reﬁnement,crystal-lographic informationﬁle(CIF),and the CSD refcodes for terpyridine compounds with water-chloride aggregates.This information is available free of charge via the Internet at .References(1)(a)Mascal,M.;Infantes,L.;Chisholm,J.Angew.Chem.,Int.Ed.2006,45,32and references therein.(b)Infantes,L.;Motherwell,S.CrystEngComm2002,4,454.(c)Infantes,L.;Chisholm,J.;Mother-well,S.CrystEngComm2003,5,480.(d)Supriya,S.;Das,S.K.J.Cluster Sci.2003,14,337.(2)(a)Das,M.C.;Bharadwaj,P.K.Eur.J.Inorg.Chem.2007,1229.(b)Ravikumar,I.;Lakshminarayanan,P.S.;Suresh,E.;Ghosh,P.Cryst.Growth Des.2006,6,2630.(c)Ren,P.;Ding,B.;Shi,W.;Wang,Y.;Lu,T.B.;Cheng,P.Inorg.Chim.Acta2006,359,3824.(d)Li,Z.G.;Xu,J.W.;Via,H.Q.;Hu,mun.2006,9,969.(e)Lakshminarayanan,P.S.;Kumar,D.K.;Ghosh,P.Inorg.Chem.2005,44,7540.(f)Raghuraman,K.;Katti,K.K.;Barbour,L.J.;Pillarsetty,N.;Barnes,C.L.;Katti,K.V.J.Am.Chem.Soc.2003,125,6955.(3)(a)Jungwirth,P.;Tobias,D.J.J.Phys.Chem.B.2002,106,6361.(b)Tobias,D.J.;Jungwirth,P.;Parrinello,M.J.Chem.Phys.2001,114,7036.(c)Choi,J.H.;Kuwata,K.T.;Cao,Y.B.;Okumura,M.J.Phys.Chem.A.1998,102,503.(d)Xantheas,S.S.J.Phys.Chem.1996,100,9703.(e)Markovich,G.;Pollack,S.;Giniger,R.;Cheshnovsky,O.J.Chem.Phys.1994,101,9344.(f)Combariza,J.E.;Kestner,N.R.;Jortner,J.J.Chem.Phys.1994,100,2851.(g)Perera, L.;Berkowitz,M.L.J.Chem.Phys.1991,95,1954.(h)Dang,L.X.;Rice,J.E.;Caldwell,J.;Kollman,P.A.J.Am.Chem.Soc.1991, 113,2481.(4)(a)Custelcean,R.;Gorbunova,M.G.J.Am.Chem.Soc.2005,127,16362.(b)Kopylovich,M.N.;Tronova,E.A.;Haukka,M.;Kirillov,A.M.;Kukushkin,V.Yu.;Fraústo da Silva,J.J.R.;Pombeiro,A.J.L.Eur.J.Inorg.Chem.2007,4621.(c)Butchard,J.R.;Curnow,O.J.;Garrett,D.J.;Maclagan,R.G.A.R.Angew.Chem.,Int.Ed.2006, 45,7550.(5)(a)Reger,D.L.;Semeniuc,R.F.;Pettinari,C.;Luna-Giles,F.;Smith,M.D.Cryst.Growth.Des.2006,6,1068and references therein.(b) Saha,M.K.;Bernal,mun.2005,8,871.(c) Prabhakar,M.;Zacharias,P.S.;Das,mun.2006,9,899.(d)Lakshminarayanan,P.S.;Suresh,E.;Ghosh,P.Angew.Chem.,Int.Ed.2006,45,3807.(e)Ghosh,A.K.;Ghoshal,D.;Ribas,J.;Mostafa,G.;Chaudhuri,N.R.Cryst.Growth.Des.2006,6,36.(f)Deshpande,M.S.;Kumbhar,A.S.;Puranik,V.G.;Selvaraj, K.Cryst.Growth Des.2006,6,743.(6)(a)Karabach,Y.Y.;Kirillov,A.M.;da Silva,M.F.C.G.;Kopylovich,M.N.;Pombeiro,A.J.L.Cryst.Growth Des.2006,6,2200.(b) Kirillova,M.V.;Kirillov,A.M.;da Silva,M.F.C.G.;Kopylovich, M.N.;Fraústo da Silva,J.J.R.;Pombeiro,A.J.L.Inorg.Chim.Acta2008,doi:10.1016/j.ica.2006.12.016.(7)The Cambridge Structural Database(CSD).Allen, F.H.ActaCrystallogr.2002,B58,380.(8)The searching algorithm in the ConQuest Version1.9(CSD version5.28,August2007)constrained to the presence of any terpyridinemoiety and at least one crystallization water molecule and one chloride counter ion resulted in43analyzable hits from which40compounds contain diverse water-chloride aggregates(there are29and11 examples of inﬁnite(mostly1D)networks and discrete clusters, respectively).See the Supporting Information for the CSD refcodes.(9)For a recent review,see Constable,E.C.Chem.Soc.Re V.2007,36,246.(10)For recent examples of supramolecular terpyridine compounds,see(a)Beves,J.E.;Constable,E.C.;Housecroft,C.E.;Kepert,C.J.;Price,D.J.CrystEngComm2007,9,456.(b)Zhou,X.-P.;Ni,W.-X.;Zhan,S.-Z.;Ni,J.;Li,D.;Yin,Y.-G.Inorg.Chem.2007,46,2345.(c)Shi,W.-J.;Hou,L.;Li,D.;Yin,Y.-G.Inorg.Chim.Acta2007,360,588.(d)Beves,J.E.;Constable,E.C.;Housecroft,C.E.;Kepert,C.J.;Neuburger,M.;Price,D.J.;Schaffner,S.CrystEngComm2007,9,1073.(e)Beves,J. E.;Constable, E. C.;Housecroft, C. E.;Neuburger,M.;Schaffner,mun.2007,10,1185.(f)Beves,J.E.;Constable,E.C.;Housecroft,C.E.;Kepert,C.J.;Price,D.J.CrystEngComm2007,9,353.(11)Synthesis of1:FeCl2·2H2O(82mg,0.50mmol)and4′-phenyl-2,2′:6′,2″-terpyridine(L)(154mg,0.50mmol)were combined in a THF (20mL)solution with continuous stirring at room temperature.The resulting deep purple suspension was stirred for1h,ﬁltered off,washed with THF(3×15mL),and dried in vacuo to afford a deep purple solid1(196mg,41%).1exhibits a high afﬁnity for water and upon recrystallization gives derivatives with a higher varying content of crystallization water.1is soluble in H2O,MeOH,EtOH,MeCN, CH2Cl2,and CHCl3.mp>305°C(dec.).Elemental analysis.Found: C52.96,H3.76,N8.36.Calcld.for C42H40Cl4Fe2N6O5:C52.42,H4.19,N8.73.FAB+-MS:m/z:835{[FeL2]Cl2·5H2O+H}+,816784Crystal Growth&Design,Vol.8,No.3,2008Communications{[FeL2]Cl2·4H2O}+,796{[FeL2]Cl2·3H2O–2H}+,781{[FeL2]Cl2·2H2O+H}+,763{[FeL2]Cl2·H2O+H}+,709{[FeL2]Cl}+,674 {[FeL2]}+,435{[FeL]Cl2}+,400{[FeL]Cl}+,364{[FeL]–H}+,311 {L–2H}+.IR(KBr):νmax/cm–1:3462(m br)ν(H2O),3060(w),2968 (w)and2859(w)ν(CH),1656(m br)δ(H2O),1611(s),1538(w), 1466(m),1416(s),1243(m),1159(w),1058(m),877(s),792(s), 766(vs),896(m),655(w),506(m)and461(m)(other bands).The X-ray quality crystals of[FeL2]Cl2·10H2O(1′)were grown by slow evaporation,in air at ca.20°C,of a MeOH/H2O(v/v)9/1)solution of1.(12)Crystal data:1′:C42H50Cl2FeN6O10,M)925.63,triclinic,a)10.1851(10),b)12.2125(13),c)19.5622(19)Å,R)76.602(6),)87.890(7),γ)67.321(6)°,U)2180.3(4)Å3,T)150(2)K,space group P1j,Z)2,µ(Mo-K R))0.532mm-1,32310reﬂections measured,8363unique(R int)0.0719)which were used in all calculations,R1)0.0469,wR2)0.0952,R1)0.0943,wR2)0.1121 (all data).(13)(a)McMurtrie,J.;Dance,I.CrystEngComm2005,7,230.(b)Nakayama,Y.;Baba,Y.;Yasuda,H.;Kawakita,K.;Ueyama,N.Macromolecules2003,36,7953.(c)Kabir,M.K.;Tobita,H.;Matsuo,H.;Nagayoshi,K.;Yamada,K.;Adachi,K.;Sugiyama,Y.;Kitagawa,S.;Kawata,S.Cryst.Growth Des.2003,3,791.(14)Ludwig,R.Angew.Chem.,Int.Ed.2001,40,1808.(15)The searching algorithm in the ConQuest Version1.9(CSD version5.28,May2007)was constrained to the presence of(i)at least onetetranuclear[(H2O)3(Cl)]–ring(i.e.,minimal cyclic fragment in our water-chloride network)with d(O···O))2.2–3.2Åand d(O···Cl) )2.6–3.6Å,and(ii)at least one crystallization water molecule andone chloride counter ion.All symmetry-related contacts were taken into consideration.(16)For2D networks with the[(H2O)3(Cl)]–core,see the CSD refcodes:AGETAH,AMIJAH,BEXVIJ,EXOWIX,FANJUA,GAFGIE, HIQCIT,LUNHUX,LUQCEF,PAYBEW,TESDEB,TXCDNA, WAQREL,WIXVUU,ZUHCOW.For3D network,see the CSD refcode:LUKZEW.(17)This analysis was run on1since we were unable to get1′in a sufﬁcientamount due to the varying content of crystallization water in the samples obtained upon recrystallization of1.(18)(a)Das,S.;Bhardwaj,P.K.Cryst.Growth.Des.2006,6,187.(b)Wang,J.;Zheng,L.-L.;Li,C.-J.;Zheng,Y.-Z.;Tong,M.-L.Cryst.Growth.Des.2006,6,357.(c)Ghosh,S.K.;Ribas,J.;El Fallah, M.S.;Bharadwaj,P.K.Inorg.Chem.2005,44,3856.(19)A temperature below305°C has been used to avoid the eventualdecomposition of the compound upon rather prolonged heating.CG7010315Communications Crystal Growth&Design,Vol.8,No.3,2008785。

KNR_publications (Kenneth N Raymond 海水提铀方面)

9/30/2010PUBLICATIONS OF KENNETH N. RAYMOND1. Kenneth N. Raymond and Fred Basolo, “The Isolation of Pentacyanonickelate(II) Salts,”Inorg. Chem.1966, 5, 949-950.2. Kenneth N. Raymond and Fred Basolo, “The Synthesis of a Molecular Metal ComplexContaining Both M-N and M-S Bonded Thiocyanate Ions,” Inorg. Chem.1966, 5, 1632-1633.3. Kenneth N. Raymond, P. W. R. Corfield and James A. Ibers, “New Conformers ofTris(ethylenediamine)chromium(III),” Inorg. Chem.1968, 7, 842-844.4. Kenneth N. Raymond, Devon W. Meek and James A. Ibers, “The Structure ofHexaamminechromium(III) Pentachlorocuprate(II), [Cr(NH3)6][CuCl5],” Inorg. Chem.1968, 7, 1111-1117.5. Kenneth N. Raymond, P. W. R. Corfield and James A. Ibers, “The Structure ofTris(ethylenediamine)chromium(III) Pentacyanonickelate(II) Sesquihydrate,[Cr(NH2CH2CH2NH2)3][Ni(CN)5]•1.5H2O,” Inorg. Chem.1968, 7, 1362-1372.6. William E. Hatfield, Robin Whyman, Robert C. Fay, Kenneth N. Raymond and FredBasolo, “Lattice-stabilized Complex Ions,” Inorg. Syn.1968, 11, 48-52.7. Kenneth N. Raymond and James A. Ibers, “The Structure of Tris(ethylenediamine)-chromium(III) Hexacyanocobaltate(III) Hexahydrate, [Cr(C2H8N2)3][Co(CN)6]•6H2O,”Inorg. Chem.1968, 7, 2333-2338.8. Allan Zalkin and Kenneth N. Raymond, “The Structure of Di-π-cycloocta-tetraeneuranium (Uranocene),” J. Am. Chem. Soc.1969, 91, 5667-5668.9. R. Lyle Patton and Kenneth N.Raymond, “The Crystal and Molecular Structure ofS2N2(SbCl5)2,” Inorg. Chem.1969, 8, 2426-2431.10. Kenneth N. Raymond, “An Example of a New Type of Five-coordinate Transition MetalComplex: [Cr(NH3)6][CuBr3Cl2],” Chem. Comm.1969, 1294-1295.11. Aristides Terzis, Kenneth N. Raymond and Thomas G. Spiro, “On the Structure ofNi(CN)53-. Raman, Infrared, and X-ray Crystallographic Evidence,” Inorg. Chem.1970, 9, 2415-2420.12. K. N. Raymond and H. R. Wenk, “Lunar Ilmenite (Refinement of the Crystal Structure),”Contr. Mineral. and Petrol.1971, 30, 135-140.13. Eileen N. Duesler and Kenneth N. Raymond, “Conformational Effects of IntermolecularInteractions. The Structure of Tris(ethylenediamine)-cobalt(III) MonohydrogenPhosphate Nonahydrate,” Inorg. Chem.1971, 10, 1486-1492.14. John L. Shafer and Kenneth N. Raymond, “Distorted Five-Coordinate Cobalt(II). TheStructure of Bromotris(3-aminopropyl)aminecobalt(II) Bromide Hemiethanolate,” Inorg.Chem.1971, 10, 1799-1803.15. Steven A. Goldfield and Kenneth N. Raymond, “Axial Bond Length Contraction in CuX5Complexes. The Structures of Hexaammine-chromium(III) Pentabromocuprate(II) andHexaamminechromium(III) Tribromodichlorocuprate(II),” Inorg. Chem.1971, 10, 2604-2607.16. Stephen Z. Goldberg, Eileen N. Duesler and Kenneth N. Raymond, “Crystal andMolecular Structure of [Mn(CO)4(C2PPh3)Br]—a Coordination Compound of theUnusual Carbonyl-ylide Product, Ph3P+-C≡C:-,” Chem. Comm.1971, 826-827.17. Keith O. Hodgson, D. Dempf and Kenneth N. Raymond, “Eclipsed and StaggeredConfigurations for a Methyl-substituted Cyclo-octatetraenyl Dianion Complex ofUranium(IV): X-ray Determination of the Structure of U[C8H4(CH3)4]2,” Chem. Comm.1971, 1592-1593.18. Keith O. Hodgson and Kenneth N. Raymond, “A Dimeric π-Cyclooctatetraene DianionComplex of Cerium(III). The Crystal and Molecular Structure of[Ce(C8H8)Cl•2OC4H8]2,” Inorg. Chem.1972, 11, 171-175.19. Kenneth N. Raymond, “Application of Constraints to Derivatives in Least-SquaresRefinement,” Acta Crystallogr.1972, A28, 163-166.20. Alex Avdeef, Kenneth N. Raymond, Keith O. Hodgson and Allan Zalkin, “TwoIsostructural Actinide π Complexes. The Crystal and Molecular Structure ofBis(cyclooctatetraenyl)uranium(IV), U(C8H8)2, and Bis(cycloocta-tetraenyl)thorium(IV), Th(C8H8)2,” Inorg. Chem.1972, 11, 1083-1088.21. Stephen Z. Goldberg, Eileen N. Duesler and Kenneth N. Raymond, “The Crystal andMolecular Structure of [Mn(CO)4(C2P(C6H5)3)Br]. A Coordination Compound of theUnusual Carbonyl-Ylide Reaction Product (C6H5)3P+-C≡C:-,” Inorg. Chem.1972, 11,1397-1401.22. Leo D. Brown, Kenneth N. Raymond and Stephen Z. Goldberg, “Preparation andStructural Characterization of Barium Decacyanodicobaltate(II) Tridecahydrate,Ba3[Co2(CN)10]•13H2O, an Air Stable Salt of the [Co2(CN)10]6- Ion,” J. Am. Chem. Soc.1972, 94, 7664-7674.23. Keith O. Hodgson and Kenneth N. Raymond, “An Ion Pair Complex Formed betweenBis(cyclooctatetraenyl)cerium(III) Anion and an Ether-Coordinated Potassium Cation.The Crystal and Molecular Structure of [K((CH3OCH2CH2)2O)][Ce(C8H8)2],” Inorg.Chem.1972, 11, 3030-3035.24. Frances A. Jurnak and Kenneth N. Raymond, “Conformations of Six-Membered Rings inTris Metal Complexes. A Skew-Boat Conformation in [Cr(NH2CH2CH2CH2NH2)3]3+,”Inorg. Chem.1972, 11, 3149-3152.25. Keith O. Hodgson and Kenneth N. Raymond, "Rotomeric Configurations of a Methyl-Substituted Cyclooctatetraene Dianion Complex of Uranium(IV). Crystal and Molecular Structure of Bis(l,3,5,7-tetramethylcyclooctatetraenyl)uranium(IV), U(C8H4(CH3)4)2,”Inorg. Chem.1973, 12, 458-466.26. John Leong, Keith O. Hodgson and Kenneth N. Raymond, “Preparation and StructuralCharacterization of Tris(benzylcyclopentadienide)-chlorouranium(IV),U(C5H4CH2C6H5)3Cl,” Inorg. Chem.1973, 12, 1329-1335.27. H. R. Wenk and K. N. Raymond, “Four New Structure Refinements of Olivine,” Z.Kristallogr.1973, 137, 86-105.28. William G. Dauben, Andrew J. Kielbania, Jr. and Kenneth N. Raymond, “TransitionMetal Catalyzed Rearrangements of Bicyclobutanes. Mechanism of Acid Production in Methanolysis,” J. Am. Chem. Soc.1973, 95, 7l66-7168.29. Stephen Z. Goldberg and Kenneth N. Raymond, “Trans Interaction in a Metal Carbonyl.Structure of ((Triphenylphosphinemethylide)diphenylphosphine-oxide)pentacarbonyl-tungsten(0), W(CO)5(O=P(C6H5)2CHP(C6H5)3),” Inorg. Chem.1973, 12, 2923-2927. 30. Stephen Z. Goldberg, Kenneth N. Raymond, C. A. Harmon and David H. Templeton,“Structure of the 10π Electron Cyclooctatetraene Dianion in Potassium Diglyme 1,3,5,7-Tetramethylcyclooctatetraene Dianion, [K((CH3OCH2CH2)2O)]2[C8H4(CH3)4],” J. Am.Chem. Soc.1974, 96, 1348-1351.31. John Leong and Kenneth N. Raymond, “Coordination Isomers of Biological IronTransport Compounds. I. Models for the Siderochromes. The Geometrical and Optical Isomers of Tris(N-methyl-l-menthoxyacethydroxamato)chromium(III),” J. Am. Chem.Soc.1974, 96, 1757-1762.32. Steven A. Goldfield and Kenneth N. Raymond, “Axial vs. Equatorial Bonding inTrigonal-Bipyramidal Complexes. Crystal and Molecular Structure of[Bis(triphenylphosphine)-imminium]tetracarbonylcyanoiron(0),[((C6H5)3P)2N][Fe(CO)4CN],” Inorg. Chem.1974, 13, 770-775.33. Leo D. Brown and Kenneth N. Raymond, “σ-Bonded Dioxygen. X-ray Crystal Structureof [NEt4]3[Co(CN)5(O2)], 5H2O,” J. Chem. Soc., Chem. Comm.1974, 470-471.34. John Leong, J. B. Neilands and Kenneth N. Raymond, “Coordination Isomers ofBiological Iron Transport Compounds. III. Transport of Λ-cis-ChromicDesferriferrichrome by Ustilago sphaerogena,” Biochem. Biophys. Res. Comm.1974, 60, 1066-1071.35. Edgar C. Baker, Gordon W. Halstead and Kenneth N. Raymond, “The Structure andBonding of 4f and 5f π Sandwich Organometallic Compounds,” John M. Haschke andHarry A. Eick, Eds., Proceedings of the 11th Rare Earth Research Conference, Volume I, Sessions A through J, Traverse City, Michigan, October 7-10, 1974, pp 284-289. Review36. Frances A. Jurnak and Kenneth N. Raymond, “Effect of Packing Forces on the Geometryof the [Ni(CN)5]3- Ion: Structures of [Cr(NH2CH2CH2CH2NH2)3] [Ni(CN)5]•2H2O and[Cr(NH3)6][Ni(CN)5]•2H2O. A Skew-Boat Conformation in a Six-Membered MetalChelate Ring,” Inorg. Chem.1974, 13, 2387-2397.37. John Leong and Kenneth N. Raymond, “Coordination Isomers of Biological IronTransport Compounds. II. The Optical Isomers of Chromic Desferriferrichrome andDesferriferrichrysin,” J. Am. Chem. Soc.1974, 96, 6628-6630.38. Leo D. Brown and Kenneth N. Raymond, “X-ray Structure of the Pentacyanocobaltate(II)Anion in Diethyldi-isopropylammonium Pentacyanocobaltate,” J. Chem. Soc., Chem.Comm.1974, 910-911.39. Edgar C. Baker, Kenneth N. Raymond, Tobin J. Marks, William A. Wachter, “Isolationand Structural Characterization of a µ-Di(η5:η1-cyclopentadienyl)dithorium(IV)Complex,” J. Am. Chem. Soc.1974, 96, 7586-7588.40. John Leong and Kenneth N. Raymond, “Coordination Isomers of Biological IronTransport Compounds. IV. Geometrical Isomers of Chromic Desferriferrioxamine B,” J.Am. Chem. Soc.1975, 97, 293-296.41. Leo D. Brown, Douglas R. Greig and Kenneth N. Raymond, “Structure of the ChloroformAdduct of Pentakis(phenyl isocyanide)cobalt(I) Perchlorate,[Co(CNC6H5)5]ClO4•HCCl3,” Inorg. Chem.1975, 14, 645-649.42. Gordon W. Halstead, Edgar C. Baker and Kenneth N. Raymond, “σ- vs. π-BondedOrganoactinides. The Synthesis and Structural Analysis of Tris(η5-cyclopentadienyl)-η1-2-methylallyluranium(IV),” J. Am. Chem. Soc.1975, 97, 3049-3052.43. Edgar C. Baker, Leo D. Brown and Kenneth N. Raymond, “Structural Characterization ofa Chloride-Bridged Lanthanide Cyclopentadienyl Dimer, [Yb(C5H4CH3)2Cl]2,” Inorg.Chem.1975, 14, 1376-1379.44. Frances A. Jurnak, Douglas R. Greig and Kenneth N. Raymond, “StructuralCharacterization of the Pentakis(phenylisocyanide)cobalt(II) Ion in the Salt of[Co(CNC6H5)5][ClO4]2•½ClCH2CH2Cl,” Inorg. Chem.1975, 14, 2585-2589.45. Leo D. Brown and Kenneth N. Raymond, “Structural Characterization of the Pentacyano-cobaltate(II) Anion in the Salt [NEt2(i-Pr)2]3[Co(CN)5],” Inorg. Chem.1975, 14, 2590-2594.46. Leo D. Brown and Kenneth N. Raymond, “A σ-Bonded Dioxygen Adduct of thePentacyanocobaltate(II) Anion. Crystal Structure of [N(C2H5)4]3 [Co(CN)5(O2)]•5H2O,”Inorg. Chem.1975,14, 2595-2601.47. Edgar C. Baker, Gordon W. Halstead and Kenneth N. Raymond, “The Structure andBonding of 4f and 5f Series Organometallic Compounds,” in Structure and Bonding, Vol.25, J. D. Dunitz, P. Hemmerich, R. H. Holm, J. A. Ibers, C. K. Jorgensen, J. B. Neilands,D. Reinen, R. J. P. Williams, Eds., Springer Verlag, Berlin Heidelberg, New York, 1976,pp 23-68. Review48. Stephan S. Isied, Gilbert Kuo and Kenneth N. Raymond, “Coordination Isomers ofBiological Iron Transport Compounds. V. The Preparation and Chirality of theChromium(III) Enterobactin Complex and Model Tris(catechol)chromium(III)Analogues,” J. Am. Chem. Soc.1976, 98, 1763-1767.49. Kenneth N. Raymond, Stephan S. Isied, Leo D. Brown, Frank R. Fronczek and J. HunterNibert, “Coordination Isomers of Biological Iron Transport Compounds. VI. Models of the Enterobactin Coordination Site. A Crystal Field Effect in the Structure of Potassium Tris(catecholato)chromate(III) and -ferrate(III) Sesquihydrates, K3[M(O2C6H4)3]•1.5H2O, M = Cr, Fe,” J. Am. Chem. Soc.1976, 98, 1767-1774.50. Frank R. Fronczek, Gordon W. Halstead and Kenneth N. Raymond, “Actinide Metallo-carbaborane Complex: Synthesis and X-ray Structure Determination of the Bis[η5-(3)-l,2-dicarbollyl]dichlorouranium(IV) Dianion,” J. Chem. Soc., Chem. Comm.1976, 279-251.51. Frank R. Fronczek, Edgar C. Baker, Paul R. Sharp, Kenneth N. Raymond, Helmut G. Altand Marvin D. Rausch, “The Structures of Dimethylhafnocene and Its HydrolysisProduct, µ-Oxo-bis(methylhafnocene),” Inorg. Chem.1976, 15, 2284-2289.52. Frank R. Fronczek, Gordon W. Halstead and Kenneth N. Raymond, “The Synthesis,Crystal Structure, and Reactions of an Actinide Metallocarborane Complex, Bis(η5-(3)-l,2-dicarbollyl)dichlorouranium(IV) Dianion, [U(C2B9H11)2C l2]2-,” J. Am. Chem. Soc.1977, 99, 1769-1775.53. Kamal Abu-Dari and Kenneth N. Raymond, “Coordination Isomers of Biological IronTransport Compounds. 8. The Resolution of Tris(hydroxamato) andTris(thiohydroxamato) Complexes of High-Spin Iron(III),” J. Am. Chem. Soc.1977, 99, 2003-2005.54. Kamal Abu-Dari and Kenneth N. Raymond, “Coordination Isomers of Biological Iron-Transport Compounds. 7. Preparation and Resolution of Tris(thiobenzohydroxamato)-chromium(III), -cobalt(III), and (High-Spin)-iron(III) Complexes,” Inorg. Chem.1977,16, 807-812.55. Bioinorganic Chemistry - II. Advances in Chemistry Series, No. 162, Raymond, K. N.,Ed., American Chemical Society, Washington, D.C., 1977. Book56. Kenneth N. Raymond, “Kinetically Inert Complexes of the Siderophores in Studies ofMicrobial Iron Transport,” reprinted from Bioinorganic Chemistry - II, Advances inChemistry Series, No. 162, K. N. Raymond, Ed., American Chemical Society:Washington, D.C., 1977, pp 33-54. Review57. Edgar C. Baker and Kenneth N. Raymond, “Synthetic, Structural, and Magneticproperties of the Pyrazine-Bridged Lanthanide Organometallic Complex µ-Pyrazine-bis[tris(cyclo-pentadienide)ytterbium(III)], (C5H5)3Yb(NC4H4N)Yb(C5H5)3,” Inorg.Chem.1977, 16, 2710-2714.58. Frederick L. Weitl, Kenneth N. Raymond, William L. Smith and Thomas R. Howard,“Specific Sequestering Agents for the Actinides. l. N,N',N",N"'-Tetra(2,3-dihydroxy-benzoyl)tetraazacyclotetra- and -hexadecanes,” J. Am. Chem. Soc.1978, 100, 1170-1172.59. William L. Smith, James D. Ekstrand and Kenneth N. Raymond, “High-Yield Synthesisand Crystal Structure of l,5,9,13-Tetraazacyclohexadecane ([16]aneN4),” J. Am. Chem.Soc.1978, 100, 3539-3544.60. Carl J. Carrano and Kenneth N. Raymond, “Synthesis and Characterization of IronComplexes of Rhodotorulic Acid: A Novel Dihydroxamate Siderophore and PotentialChelating Drug,” J. Chem. Soc., Chem. Comm.1978, 501-502.61. Eileen N. Duesler and Kenneth N. Raymond, “The Structures and Conformations of theMixed Ethylenediamine 1,3-Propanediamine Complexes [Cr(en)2(tn)]Br3•H2O and[Cr(en)(tn)2]I3•H2O,” Inorg. Chimica Acta1978, 30, 87-95.62. Alex Avdeef, Stephen R. Sofen, Thomas L. Bregante and Kenneth N. Raymond.“Coordination Chemistry of Microbial Iron Transport Compounds. 9. Stability Constants for Catechol Models of Enterobactin,” J. Am. Chem. Soc.1978, 100, 5362-5370.63. Carl J. Carrano and Kenneth N. Raymond, “Coordination Chemistry of Microbial IronTransport Compounds. 10. Characterization of the Complexes of Rhodotorulic Acid, a Dihydroxamate Siderophore,” J. Am. Chem. Soc.1978, 100, 5371-5374.64. Stephen R. Cooper, James V. McArdle and Kenneth N. Raymond, “SiderophoreElectrochemistry: Relation to Intracellular Iron Release Mechanism,” Proc. Natl. Acad.Sci. USA1978, 75, 3551-3554.65. James V. McArdle, Stephen R. Sofen, Stephen R. Cooper and Kenneth N. Raymond,“Coordination Chemistry of Microbial Iron Transport Compounds. 13. Preparation and Chirality of the Rhodium(III) Enterobactin Complex and ModelTris(catecholato)rhodate(III) Analogues,” Inorg. Chem.1978, 17, 3075-3078.66. Kamal Abu-Dari, Stephen R. Cooper, and Kenneth N. Raymond, “CoordinationChemistry of Microbial Iron Transport Compounds. 15. Electrochemistry and Magnetic Susceptibility of Iron(III)-Hydroxamate and -Thiohydroxamate Complexes,” Inorg.Chem.1978, 17, 3394-3397.67. Carl J. Carrano and Kenneth N. Raymond, “Coordination Chemistry of Microbial IronTransport Compounds: Rhodotorulic Acid and Iron Uptake in Rhodotorula pilimanae,” J.Bacteriol.1978, 136, 69-74.68. Stephen R. Sofen, Kamal Abu-Dari, Derek P. Freyberg and Kenneth N. Raymond,“Specific Sequestering Agents for the Actinides. 2. A Ligand Field Effect in the Crystal and Molecular Structures of Tetrakis(catecholato)uranate(IV) and -thorate(IV),” J. Am.Chem. Soc.1978, 100, 7882-7887.69. Kamal Abu-Dari, James D. Ekstrand, Derek P. Freyberg and Kenneth N. Raymond,“Coordination Chemistry of Microbial Iron Transport Compounds. 14. Isolation andStructural Characterization of transTris(benzohydroxamato)chromium(III)-2-(2-Propanol),” Inorg. Chem.1979, 18, 108-112.70. Stephen R. Sofen, David C. Ware, Stephen R. Cooper and Kenneth N. Raymond,“Structural, Electrochemical, and Magnetic Properties of a Four-Membered Redox Series ([Cr(L)3]n-, n = 0-3) in Catechol-Benzoquinone Complexes of Chromium,” Inorg. Chem.1979, 18, 234-239.71. Carl J. Carrano, Stephen R. Cooper and Kenneth N. Raymond, “Coordination Chemistryof Microbial Iron Transport Compounds. 11. Solution Equilibria and Electrochemistry of Ferric Rhodotorulate Complexes,” J. Am. Chem. Soc.1979, 101, 599-604.72. Derek P. Freyberg, John L. Robbins, Kenneth N. Raymond and James C. Smart, “Crystaland Molecular Structures of Decamethylmanganocene and Decamethylferrocene. Static Jahn-Teller Distortion in a Metallocene,” J. Am. Chem. Soc.1979, 101, 892-897.73. Wesley R. Harris, Frederick L. Weitl and Kenneth N. Raymond, “Synthesis andEvaluation of an Enterobactin Model Compound. 1,3,5-Tris(2,3-dihydroxybenzoylaminomethyl)-benzene and its Iron(III) Complex,” J. Chem. Soc.,Chem. Comm.1979, 177-178.74. Wesley R. Harris, Carl J. Carrano and Kenneth N. Raymond, “SpectrophotometricDetermination of the Proton-Dependent Stability Constant of Ferric Enterobactin,” J. Am.Chem. Soc.1979, 101, 2213-2214.75. Kenneth N. Raymond and Carl J. Carrano, “Coordination Chemistry and Microbial IronTransport,” Acc. Chem. Res.1979, 12, 183-190. Review76. Wesley R. Harris, Carl J. Carrano and Kenneth N. Raymond, “Coordination Chemistry ofMicrobial Iron Transport Compounds. 16. Isolation, Characterization, and FormationConstants of Ferric Aerobactin,” J. Am. Chem. Soc.1979, 101, 2722-2727.77. Frederick L. Weitl and Kenneth N. Raymond, “Ferric Ion Sequestering Agents. 1.Hexadentate O-Bonding N,N',N"-Tris(2,3-dihydroxybenzoyl) Derivatives of 1,5,9-Triazacyclotridecane and 1,3,5-Triaminomethylbenzene,” J. Am. Chem. Soc.1979, 101, 2728-2731.78. Kenneth N. Raymond, “The Structure and Bonding of 4f and 5f Series OrganometallicCompounds,” in Organometallics of the f-Elements, T. J. Marks and R. D. Fischer, Eds.,D. Reidel Publishing Company: Dordrecht, Holland, 1979, pp 249-280. Review79. Alex Avdeef and Kenneth N. Raymond, “Free Metal and Free Ligand ConcentrationsDetermined from Titrations Using Only a pH Electrode. Partial Derivatives inEquilibrium Studies,” Inorg. Chem.1979, 18, 1605-1611.80. Stephen R. Sofen, Stephen R. Cooper and Kenneth N. Raymond, “Crystal and MolecularStructues of Tetrakis(catecholato)hafnate(IV) and -cerate(IV). Further Evidence for aLigand Field Effect in the Structure of Tetrakis(catecholato)uranate(IV),” Inorg. Chem.1979, 18, 1611-1616.81. Kamal Abu-Dari, Kenneth N. Raymond and Derek P. Freyberg, “The Bihydroxide(H3O2−) Anion. A Very Short, Symmetric Hydrogen Bond,” J. Am. Chem. Soc.1979,101, 3688-3689.82. Carl J. Carrano and Kenneth N. Raymond, “Ferric Ion Sequestering Agents. 2. Kineticsand Mechanism of Iron Removal from Transferrin by Enterobactin and SyntheticTricatechols,” J. Am. Chem. Soc.1979, 101, 5401-5404.83. Kamal Abu-Dari, Derek P. Freyberg and Kenneth N. Raymond, “Coordination Chemistryof Microbial Iron Transport Compounds. 18. Crystal and Molecular Structure ofDisodium Triethylmethylammonium Tris(thiobenzohydroximato)chromate(III)Hemikis(sodium hydroxide hydrate), Na2[(C2H5)3(CH3)N][Cr(PhC(S) =N(O))3]•½NaH3O2•18H2O,” Inorg. Chem.1979, 18, 2427-2433.84. Wesley R. Harris, Carl J. Carrano, Stephen R. Cooper, Stephen R. Sofen, Alex Avdeef,James V. McArdle and Kenneth N. Raymond, “Coordination Chemistry of Microbial Iron Transport Compounds. 19. Stability constants and Electrochemical Behavior of FerricEnterobactin and Model Complexes,” J. Am. Chem. Soc.1979, 101, 6097-6104.85. William L. Smith and Kenneth N. Raymond, “The Oxidation of Uranium(IV) by N-Phenylbenzohydroxamic Acid and the Structure of the Reaction Product: Chlorodioxo-N-phenylbenzohydroxamato-bis(tetrahydrofuran)uranium(VI),” J. Inorg. Nucl. Chem.1979, 41, 1431-1436.86. Wesley R. Harris and Kenneth N. Raymond, “Ferric Ion Sequestering Agents. 3. TheSpectrophotometric and Potentiometric Evaluation of Two New Enterobactin Analogues: 1,5,9-N,N',N"-Tris(2,3-dihydroxybenzoyl)-cyclotriazatridecane and 1,3,5-N,N',N"-Tris(2,3-dihydroxybenzoyl)-triaminomethylbenzene,” J. Am. Chem. Soc.1979, 101,6534-6541.87. Frederick L. Weitl, Wesley R. Harris and Kenneth N. Raymond, “SulfonatedCatecholamide Analogues of Enterobactin as Iron Sequestering Agents,” J. Med. Chem.1979, 22, 1281-1283.88. Derek P. Freyberg, Kamal Abu-Dari and Kenneth N. Raymond, “Coordination Chemistryof Microbial Iron Transport Compounds. 17. Preparation and Structural Characterization of Tris(N-methylthiobenzohydroxamato)-cobalt(III), -chromium(III), -iron(III), and -manganese(III),” Inorg. Chem.1979, 11, 3037-3043.89. William L. Smith and Kenneth N. Raymond, “Synthesis of Aliphatic Dimeric N-Isopropylhydroxamic Acids and the Crystal and Molecular Structure of N,N'-Dihydroxy-N,N'-diisopropylhexanediamide: A Hydroxamic Acid in the Trans Conformation,” J. Am.Chem. Soc.1980, 102, 1252-1255.90. Frederick L. Weitl and Kenneth N. Raymond, “Specific Sequestering Agents for theActinides. 3. Polycatecholate Ligands Derived from 2,3-Dihydroxy-5-sulfobenzoylConjugates of Diaza- and Tetraazaalkanes,” J. Am. Chem. Soc.1980, 102, 2289-2293. 91. Patricia W. Durbin, E. Sarah Jones, Kenneth N. Raymond and Frederick L. Weitl,“Specific Sequestering Agents for the Actinides. 4. Removal of 238Pu(IV) from Mice by Sulfonated Tetrameric Catechoyl Amides,” Rad. Res. 1980, 81, 170-187.92. Kenneth N. Raymond, Kamal Abu-Dari and Stephen R. Sofen, “Stereochemistry ofMicrobial Iron Transport Compounds,” from ACS Symposium Series, No. 119,Stereochemistry of Optically Active Transition Metal Compounds, Bodie E. Douglas and Yoshihiko Saito, Eds., American Chemical Society, Washington, D.C., 1980, pp 133-167. Review93. Kamal Abu-Dari and Kenneth N. Raymond, “Coordination Chemistry of Microbial IronTransport Compounds. 20. Crystal and Molecular Structures of Two Salts of cis- andtrans-Tris(benzohydroximato)- chromate(III),” Inorg. Chem.1980, 19, 2034-2040.94. Kenneth N. Raymond and Charles W. Eigenbrot, Jr., “Structural Criteria for the Mode ofBonding of Organoactinides and -lanthanides and Related Compounds,” Acc. Chem. Res.1980, 13, 276-283.95. Kenneth N. Raymond, William L. Smith, Frederick L. Weitl, Patricia W. Durbin, E.Sarah Jones, Kamal Abu-Dari, Stephen R. Sofen and Stephen R. Cooper, “SpecificSequestering Agents for the Actinides,” reprinted from ACS Symposium Series, No. 131, Lanthanide and Actinide Chemistry and Spectroscopy, Norman M. Edelstein, Ed.,American Chemical Society, Washington, D.C., 1980, 143-172. Review96. Kenneth N. Raymond, Wesley R. Harris, Carl J. Carrano and Frederick L. Weitl, “TheSynthesis, Thermodynamic Behavior, and Biological Properties of Metal-Ion-SpecificSequestering Agents for Iron and the Actinides,” reprinted from ACS Symposium Series, No. 140, Inorganic Chemistry in Biology and Medicine, Arthur E. Martell, Ed., American Chemical Society, Washington, D.C., 1980, 313-332. Review97. William L. Smith and Kenneth N. Raymond, “1,5,9,13-Tetraazacyclo-hexadecane([16]aneN4),” in Inorganic Syntheses, Vol. XX, Daryle H. Busch, Editor-in-Chief, John Wiley & Sons, Inc., New York, 1980, 109-111. Review98. Kenneth N. Raymond and William L. Smith, “Actinide-Specific Sequestering Agents andDecontamination Applications,” in Structure and Bonding, Vol. 43, J. B. Goodenough, P.Hemmerich, J. A. Ibers, C. K. Jorgensen, J. B. Neilands, D. Reinen and R. J. P. Williams, Eds., Springer-Verlag, Berlin, Heidelberg, 1981, 159-186. Review99. Frederick L. Weitl, Kenneth N. Raymond and Patricia W. Durbin, “SyntheticEnterobactin Analogues. Carboxamido-2,3-dihydroxyterephthalate Conjugates ofSpermine and Spermidine,” J. Med. Chem.1981, 24, 203-206.100. Paul R. Sharp, Kenneth N. Raymond, James C. Smart and Ronald J. McKinney, “Structure and Bonding of Bis(fulvalene)dinickel,” J. Am. Chem. Soc. 1981, 103, 753-757.101. K. N. Raymond and V. L. Pecoraro, “Coordination Chemistry,” McGraw-Hill Yearbook of Science & Technology, 1981, 150-153. Review102. Thomas P. Tufano, Vincent L. Pecoraro and Kenneth N. Raymond, “Ferric Ion Sequestering Agents. Kinetics of Iron Release from Ferritin to Catechoylamides,”Biochem. Biophys. Acta1981, 668, 420-428.103. Charles W. Eigenbrot, Jr. and Kenneth N. Raymond, “Synthesis and Crystal Structure of UCp3(C3H3N2). A New Mode of Pyrazolate Bonding,” Inorg. Chem.1981, 20, 1553-1556.104. Wesley R. Harris, Carl J. Carrano, Vincent L. Pecoraro and Kenneth N. Raymond, “Siderophilin Metal Coordination. 1. Complexation of Thorium by Transferrin:Structure-Function Implications,” J. Am. Chem. Soc.1981, 103, 2231-2237.105. Wesley R. Harris, Kenneth N. Raymond and Frederick L. Weitl, “Ferric Ion Sequestering Agents. 6. The Spectrophotometric and Potentiometric Evaluation of SulfonatedTricatecholate Ligands,” J. Am. Chem. Soc.1981, 103, 2667-2675.106. William L. Smith and Kenneth N. Raymond, “Specific Sequestering Agents for the Actinides. 6. Synthetic and Structural Chemistry of Tetrakis (N-alkylalkanehydroxamato)thorium(IV) Complexes,” J. Am. Chem. Soc.1981, 103, 3341-3349.107. Stephen M. Moerlein, Michael J. Welch, Kenneth N. Raymond and Frederick L. Weitl, “Tricatecholamide Analogs of Enterobactin as Gallium- and Indium-BindingRadiopharmaceuticals,” J. Nucl. Med.1981. 22, 710-719.108. Vincent L. Pecoraro, Frederick L. Weitl and Kenneth N. Raymond, “Ferric Ion-Specific Sequestering Agents. 7. Synthesis, Iron-Exchange Kinetics, and Stability Constants ofN-Substituted, Sulfonated Catechoylamide Analogues of Enterobactin,” J. Am. Chem.Soc.1981, 103, 5133-5140.109. Thomas P. Tufano and Kenneth N. Raymond, “Coordination Chemistry of Microbial Iron Transport Compounds. 21. Kinetics and Mechanism of Iron Exchange in Hydroxamate Siderophore Complexes,” J. Am. Chem. Soc.1981, 103, 6617-6624.110. Frederick L. Weitl and Kenneth N. Raymond, “Lipophilic Enterobactin Analogues.Terminally N-Alkylated Spermine/Spermidine Catecholcarboxamides,” J. Org. Chem.1981, 46, 5234-5237.111. Vincent L. Pecoraro, Wesley R. Harris, Carl J. Carrano and Kenneth N. Raymond, “Siderophilin Metal Coordination. Difference Ultraviolet Spectroscopy of Di-, Tri-, and Tetravalant Metal Ions with Ethylenebis[(o-hydroxyphenyl)glycine],” Biochemistry 1981, 20, 7033-7039.112. Kenneth N. Raymond, Vincent L. Pecoraro and Frederick L. Weitl, “Design of New Chelating Agents,” in Development of Iron Chelators for Clinical Use, Arthur E. Martell, W. French Anderson and David G. Badman, Eds., Elsevier/North-Holland, New York,1981, 165-187. Review113. Kamal Abu-Dari and Kenneth N. Raymond, “Specific Sequestering Agents for the Actinides. 8. Synthesis and Structural Chemistry ofTetrakis(thiohydroxamato)hafnium(IV) in Hf(CH3C6H4(S)N(O)CH3)4•C2H5OH,” Inorg.Chem.1982, 21, 1676-1679.114. K. N. Raymond, M. J. Kappel, V. L. Pecoraro, W. R. Harris, C. J. Carrano, F. L. Weitl and P. W. Durbin, “Specific Sequestering Agents for Actinide Ions,” in Actinides inPerspective, N. M. Edelstein, Ed., Pergamon Press, Oxford and New York, 1982, 491-507. Review115. K. N. Raymond, V. L. Pecoraro, W. R. Harris and C. J. Carrano, “Actinide Coordination and Discrimination by Human Transferrin,” in Environmental Migration of Long-Lived Radionuclides, International Atomic Energy Agency, Vienna, 1982, 571-577. Review 116. Vincent L. Pecoraro, Geoffrey B. Wong and Kenneth N. Raymond, “Gallium and Indium Imaging Agents. 2. Complexes of Sulfonated Catechoylamide Sequestering Agents,”Inorg.Chem.1982, 21, 2209-2215.117. Kenneth N. Raymond and Thomas P. Tufano, “Coordination Chemistry of the Siderophores and Recent Studies of Synthetic Analogues,” in The Biological Chemistry of Iron, H. Brian Dunford, David Dolphin, Kenneth N. Raymond and Larry Sieker, Eds.,D. Reidel Publishing Company, Dordrecht, Holland, 1982, 85-105. Review118. Charles W. Eigenbrot, Jr. and Kenneth N. Raymond, “Organouranium Complexes of Pyrazole and Pyrazolate. Synthesis and X-ray Structures of U(C5Me5)2Cl2(C3H4N2),U(C5Me5)2Cl(C3H4N2), and U(C5Me5)(C3H3N2)2,” Inorg. Chem.1982, 21, 2653-2660. 119. Charles W. Eigenbrot, Jr. and Kenneth N. Raymond, “Crystal and Molecular Structure of [Nd(tren)2(CH3CN)](ClO4)3,” Inorg. Chem. 1982, 21, 2867-2870.120. Stephen M. Moerlein, Michael J. Welch and Kenneth N. Raymond, “Use of Tricatecholamide Ligands to Alter the Biodistribution of Gallium-67: ConciseCommunication,” J. Nucl. Med.1982, 23, 501-506.121. Mary J. Kappel and Kenneth N. Raymond, “Ferric Ion Sequestering Agents. 10.Selectivity of Sulfonated Poly(catechoylamides) for Ferric Ion,” Inorg. Chem.1982, 21, 3437-3442.122. Stephen R. Cooper, Yun Bai Koh and Kenneth N. Raymond, “Synthetic, Structural, and Physical Studies of Bis(triethylammonium) Tris(catecholato)vanadate(IV), PotassiumBis(catecholato)- oxovanadate(IV), and Potassium Tris(catecholato)vanadate(III),” J. Am.Chem. Soc.1982, 104, 5092-5102.。

材料物理英语

材料物理英语Material Physics English。

Material physics is a branch of physics that focuses on the study of the physical properties of materials. It is a multidisciplinary field that combines principles from physics, chemistry, and engineering to understand the behavior of materials at the atomic and molecular levels. In this document, we will explore some key concepts and terms related to material physics in English.1. Crystal Structure。

The crystal structure of a material refers to the arrangement of atoms or molecules in a crystalline solid. It is an important factor that determines the physical and mechanical properties of the material. Common types of crystal structures include cubic, hexagonal, and tetragonal. Understanding the crystal structure of a material is essential for designing new materials with specific properties.2. Mechanical Properties。

结构化学英语

结构化学英语Structured ChemistryChemistry is a vast and complex field of study that encompasses the understanding of the composition, structure, and properties of matter. One of the key aspects of chemistry is the concept of structure, which plays a crucial role in determining the behavior and characteristics of chemical substances. Structural chemistry, a subfield of chemistry, focuses on the spatial arrangement of atoms and molecules, and how this arrangement influences the chemical and physical properties of materials.The study of structure in chemistry involves the investigation of the three-dimensional (3D) arrangements of atoms within molecules and the intermolecular interactions that exist between them. This knowledge is essential for understanding the behavior of chemical systems, predicting their properties, and designing new materials with desired characteristics.One of the fundamental tools used in structural chemistry is X-ray crystallography. This technique involves the bombardment of a crystalline sample with X-rays, which interact with the electrons inthe atoms of the crystal. The resulting diffraction pattern can be analyzed to determine the precise arrangement of atoms within the crystal structure. This information is crucial for understanding the properties of solid-state materials, such as metals, minerals, and ceramics.Another important technique in structural chemistry is nuclear magnetic resonance (NMR) spectroscopy. This method utilizes the magnetic properties of atomic nuclei to provide information about the chemical environment and connectivity of atoms within a molecule. NMR spectroscopy is widely used in the identification and characterization of organic compounds, as well as in the study of biomolecules, such as proteins and nucleic acids.In addition to these experimental techniques, computational methods have also become increasingly important in the field of structural chemistry. Quantum mechanical calculations, such as density functional theory (DFT), allow researchers to model the behavior of atoms and molecules at the quantum level, providing insights into their electronic structure and chemical reactivity.One of the key applications of structural chemistry is in the design and development of new materials. By understanding the relationship between the structure of a material and its properties, chemists can engineer substances with specific characteristics, suchas high strength, enhanced thermal stability, or improved electrical conductivity. This knowledge is particularly valuable in fields like materials science, nanotechnology, and catalysis.Another important aspect of structural chemistry is its role in the study of biological systems. The structures of proteins, nucleic acids, and other biomolecules are crucial for understanding their functions and interactions within living organisms. This knowledge is essential for the development of new drugs and the understanding of disease processes.In conclusion, the field of structural chemistry is a fundamental and multifaceted discipline that underpins our understanding of the physical and chemical properties of matter. Through the use of advanced experimental and computational techniques, structural chemists continue to unravel the mysteries of the molecular world, paving the way for new discoveries and innovations that have the potential to transform our lives.。

杂多酸有机无机杂化材料的合成及结构性能研究

42.毕丽华.韩正波.王恩波.黄如丹钨磷杂多阴离子[P4W30Cu4(H2O)2O112 16-]合成方法的改进及其配位水的取代反应 1999(01)
43.廖见培.刘国东.黄杉生α-P2W17O10-61杂多阴离子薄膜修饰电极的制备[期刊论文]-分析科学学报 2000(6)
44.Hoskins B F.Robson R Infinite polymeric frameworks consisting of three dimensionally linked rod-like segments 1989
45.Suh M P.Shim B Y.Yoon T S Template Syntheses and Crystal Structures of Nickel (Ⅱ) Complexes of Hexaaza Macrocyclic Ligands with Pendant
46.Functional Groups Formation of a Coordination Polymer 1994
34.Pope M T Heteropoly and Isopoly Oxometalates 1983
35.赵文彦.陈亚光.彭军α-和β-三取代钨锗杂多酸盐异构体的合成和表征 1993(03)
36.王力.刘宗瑞.王恩波取代型钨硅杂多化合物的导电性及磁性 1998(04)
37.徐靖.柳士忠以Keggin结构杂多阴离子掺杂的聚吡啶的化学合成及性能研究[期刊论文]-湖北化工 2000(5)
21.张琳萍.侯红卫.樊耀亭.程凤宏配位聚合物[期刊论文]-无机化学学报 2000(1)
22.孙为银.费宝丽.张延安.唐雯霞.郁开北含1,6-二(4′-吡啶基)-2,5-二氮杂己烷的一维链状和二维网状银(Ⅰ)超分子配合物的合成与结构[期刊论文]-化学学报 2000(5)

晶型与表面活性剂经典文献之九

Influence of Impurities on the Solution-Mediated PhaseTransformation of an Active Pharmaceutical IngredientTakashi Mukuta,†,‡Alfred Y.Lee,‡Takeshi Kawakami,†and Allan S.Myerson*,‡Process Chemistry Labs,Astellas Pharma Inc.,160-2,Akahama,Takahagi-shi,Ibaraki,318-0001Japan,and Department of Chemical and Environmental Engineering,IllinoisInstitute of Technology,Chicago,Illinois60616Received October14,2004ABSTRACT:The solution-mediated phase transformation of the metastable A form of an active pharmaceutical ingredient(1)to the stable B form is investigated in2-propanol.The transformation behavior(or rate)is quantified using powder X-ray diffraction.The studies show that the rate of transformation is sensitive to the tailor-made impurities and that the presence of certain inhibitors reduces the rate of transformation.Concurrently molecular modeling studies are undertaken to investigate the incorporation of these structurally related impurities into the crystal lattice,and it is observed that the build-in approach used in morphology predictions for additive-host systems can be applied to evaluate the extent of impurity incorporation.The build-in approach employs the attachment energy method in which the host molecules are substituted by impurity molecules,and the relative incorporation energies are calculated for various crystal faces.The order of the relative incorporation energies of the structurally similar impurities is identical to the order of the percentages of the amount of impurities incorporated into the crystal lattice as determined by high performance liquid chromatography(HPLC).IntroductionPolymorphism is the ability of a chemical entity to exist in more than one distinct crystalline form as a result of differences in the packing arrangement and/ or molecular conformation.1This phenomenon is often observed in organic molecular crystals2and is of para-mount importance in the pharmaceutical industry where different solid forms of the same chemical compound can exhibit different physical and chemical properties as well as different solubility and dissolution,which in turn affects the bioavailability and stability of the drug substance.Pharmaceutical manufacturers are required by the Food and Drug Administration to consistently produce the desired polymorph of a drug.3-5Discovery and characterization of polymorphs are crucial in the early stages of the development of the drug product,as unanticipated appearance or disappearance6of a poly-morph can impact the time to market for a drug,or in the case of ritonavir7,8it can result in a withdrawal of a commercial pharmaceutical product.As a result, polymorph screening,in which a compound is crystal-lized in various process conditions under a variety of crystallization methods(e.g.,sublimation,crystalliza-tion from the melt,vapor diffusion,thermal treatment, and crystallization from a single solvent or combinations of solvents),has been particularly important.9More recently,high-throughput crystallization screens have been developed using a combinatorial approach to capture crystal form diversity.10-14This approach en-ables a more comprehensive exploration of solid forms and has been applied to various highly polymorphic pharmaceutical compounds such as acetaminophen,15 MK-996,16ritonavir,17and sertraline HCl.16,18It is important to identify the most stable polymorph as well as to fully understand and control the conditions to obtain the desired solid form.Numerous methods and strategies have been used to control polymorphism, including capillary crystallization,19-21laser-induced nucleation,22,23solvent-drop grinding,24spray drying,25 supercritical fluid crystallization,26self-assembled mono-layers,27,28surfaces of metastable crystal forms,29nano-porous polymer monoliths and glass matrixes,30polymer heteronuclei,31and organic single-crystal surfaces that direct the selectivity of polymorphs through epitaxial matching.32,33In addition,designer additives have been shown to inhibit the formation of one polymorph,in turn promoting the crystallization of another polymorph.34,35 These additives have also been exploited to engineer crystal morphology36,37and kinetically resolve chiral molecules.38,39Similarly,impurities and synthesis byprod-ucts can influence the nucleation and growth of poly-morphs as can be seen in the case of terephthalic acid where an impurity induced twinning and inhibited a solid-state transformation,leading to the stabilization of the metastable form.40Recent works have utilized additives or impurities in manipulating the polymorphic outcome.41-45Structurally related additives or impurities may be incorporated into the host crystal lattice as crystal faces are sometimes unable to discriminate between the host and the additive/impurity molecule.46This can lead to severe consequences as incorporated impurities can alter the physical and chemical properties of the crystals and quite possibly have toxicological effects.Thus, control and minimization of the impurity content in pharmaceutical products are of utmost importance. Molecular modeling techniques employing the attach-ment energy method have shown that impurity-modified crystal habit can be successfully predicted47-52and that relative incorporation energies can be used as an indicator for the likelihood of impurity incorporation on crystal surfaces.51,52In most cases,the crystallization of polymorphs often obeys Ostwald’s Law of Stages53where the kinetically*To whom correspondence should be addressed.Phone:312-567-3163.Fax:312-567-7018.E-mail:myerson@.†Astellas Pharma Inc.‡Illinois Institute of Technology.20054 1429143610.1021/cg049646j CCC:$30.25©2005American Chemical SocietyPublished on Web05/18/2005metastable form initially appears followed by its trans-formation to the more stable polymorph.Understanding the different factors (e.g.,solvent,temperature,and agitation rate)that affect the conversion between the forms is essential as these variables can facilitate or impede the transformation rate.In addition,impurities in the process can also impact the transformation behavior as evident in studies in which additives can stabilize the kinetic crystal form.40-45In this work,the influence of four structurally related impurities on the solution-mediated phase transforma-tion of an active pharmaceutical ingredient (1)is investigated.The polymorphic transformation is moni-tored using powder X-ray diffraction,and the extent of impurity incorporation is determined by high perfor-mance liquid chromotography (HPLC)and compared to relative incorporation energies derived for measuring the compatibility of impurity with the host crystal lattice.The four structurally related compounds were chemically synthesized and chosen as model inhibitors.Experimental SectionMaterials.Cyclohexane and 2-propanol were obtained from Pharmco Products (Brookfield,CT).Form B of compound 1was supplied from Astellas Pharma Inc.and used without further purification.The A form was prepared from cyclohex-ane at reflux temperature.Form C was crystallized in a mixture of ethyl acetate and n -heptane.The structurally related compounds RS1,RS2,RS3,and RS4as shown in Figure 1were synthesized and have been identified by nuclear magnetic resonance (NMR)and mass spectroscopy (MS).Solubility and Dissolution.The solubility of each poly-morph of compound 1was measured in the temperature range of 0to 40°C and determined by high performance liquid chromatography (HPLC)using a Shimadzu HPLC system (YMC-GEL ODS column,injection volume was 5µL,flow rate was 1.0mL/min,UV detector was set at 210nm and the mobile phase consisted of 40%acetonitrile/60%phosphoric acid buffer pH 5.0).The experimental setup consisted of a 50mL glass vessel equipped with an agitator where 200mg of compound 1was suspended in 10mL of 2-propanol at a desired temper-ature controlled by a thermostat.After 30min,the solution was filtered and the concentration of compound 1in the supernatant was determined by HPLC.The residual crystal of compound 1on the filter was dried,and powder X-ray diffraction was performed to ensure that the polymorph transformation did not occur during solubility measurement.Also,the stable polymorph concentration after the solution-mediated phase transformation was determined by HPLC in the absence and the presence of the impurities.To measure the amount of impurities incorporated in compound 1,the crystals were dissolved in the mobile phase.After dissolution,the amount of impurities in the effluent or the degree of impurity incorporation within the crystal lattice was determined by HPLC analysis.Crystallization Studies.The solution-mediated phase transformation of the metastable A form of compound 1to the stable B form was carried out at 30°C.Experiments were performed in a 100mL three-neck flask equipped with a mechanical stirrer (stirring speed of 300rpm).The tempera-ture was chosen in to avoid the appearance of form C being mixed with form B since form C was more stable below 20°C despite having a long transformation time from form B to form C.Different concentrations of impurities RS1,RS2,RS3,and RS4were mixed with form A and added into 100mL of 2-propanol.Samples were removed at desired time intervals;the solid phase was immediately filtered under reduced pressure,and the physically adsorbed solvent was removed by drying for 15h at 30°C.The phase composition in the solid was examined by powder X-ray diffraction,and the level of impurities incorporated in the crystal lattice was assessed by HPLC.Also the effects of seeding of the stable B form on the rate of transformation were studied.Two different seeding levels (0.1and 0.5wt %)were used in the presence of the most effective inhibitor.The form B seed crystals were added to the slurry of the A form at time 0s and at 30°C.Scanning Electron Microscopy.The morphology of each crystalline form was observed with a scanning electron mi-croscope (SEM,Hitachi S-800).Samples were sputter coated with gold before examination to improve conductivity,and images were acquired at an operating voltage of 5kV.Single-Crystal X-ray Structure Determination.Data were collected using a four axis single-crystal X-ray diffrac-tometer (Rigaku AFC-7R)at ambient temperature.Measure-ments were carried out under the following conditions:graph-ite monochromated CuK R (λ)0.154178nm)radiation;voltage,40kV;current,40mA;and scanning speed,8°/min.The crystal structures for all three polymorphs were solved by direct methods with the crystallographic software package,teXsan.54Powder X-ray Diffraction.X-ray powder diffraction was obtained with a Rigaku Miniflex diffractometer with CuK R radiation (λ)0.15418nm),and measurements were carried out at a power of 30kv and 15mA.Samples were manually ground into fine powder in a mortar and pestle and packed on glass slides for analysis.Data were collected from 3°to 30°with a scan rate and step size of 1°/min and 0.1°,respectively.Powder X-ray diffraction was utilized to quantify the relative amounts of forms A and B present in the mixture based on the differences between the two distinct powder patterns.For calculation purposes,the area of all the peaks in the scan range (3°to 30°)of both forms were utilized.The conversion to form B or the content of form A of the sample collected with time was determined on the basis of the area ratio of the X-ray peaks of the two crystalline forms.Binary mixtures of both polymorphic forms in various ratios were prepared in a mortar and pestle.Figure 2shows typical powder patterns for a number of standard mixtures of different compositions (0,30,50,70,and 100wt %of form A).It can be seen that there are four unique peaks in the powder pattern for form A (2θ)6.8°,13.4°,21.6°,and 24.4°)that can be differentiated from peaks of pure form B.Thus,the ratio of the area of these four characteristic peaks for the two forms was chosen for use in the construction of a calibration curve for determining quan-titatively the polymorphic composition.The calibrationcurveFigure 1.Molecular structures of compound 1and the structurally related impurities.1430Crystal Growth &Design,Vol.5,No.4,2005Mukuta et al.for the extent of phase transformation of form A to form B is shown in Figure 3.Molecular Modeling.Relative incorporation or binding energy calculations,including molecular dynamics (MD)and mechanics simulations,were carried out with the software Cerius 2.The molecular modeling methodology and details of the procedures for the build-in approach have been described elsewhere.47Briefly,the build-in approach consists of four main steps.First molecular mechanics (MM)simulations are performed using a suitable potential function to predict the crystal morphology to identify the morphologically important faces.Next,in each symmetry position of the unit cell,the host molecule is replaced by an impurity molecule.Molecular mechanics simulations are then carried out again,using the conjugate gradient method 55to minimize the energy of the impurity molecule within the host crystal lattice,in combina-tion with MD simulations,where external forces on the molecule are applied and Newton’s equations of motions are solved to compute the new atomic positions.This sequence of MM and MD simulations is repeated until a global minimumenergy is obtained to ensure that the conformation of the impurity molecule is adjusted in such a way that it is situated at its optimum position within the host crystal lattice.In this work,the DREIDING 2.2156force field is used for all molecular simulations,van der Waals forces are modeled with the Lennard-Jones 12-6expression,and hydrogen bonding energy is approximated using a Lennard-Jones-like 12-10expression.Partial atomic charges are calculated with MOPAC using a modified neglect of diatomic overlap (MNDO)Hamiltonian approximation,57and the Ewald summation technique is utilized for the summation of long-range van der Waals and electrostatic interactions under the periodic boundary condi-tions.In the final step,attachment energy 58calculations are performed with the impurity species in each symmetry position and the relative incorporation energy for each crystal face is given bywhere E hkl b ,E hkl sl ,and E hkl attare the incorporation energy of the host molecule on the {hkl }face,the slice energy,and the attachment energy of the {hkl }face,respectively.K i is the ratio of the lattice energy of the pure crystal to the lattice energy of the crystal with the impurity in symmetry position i .The lattice energy is calculated by summing all the atom -atom interactions between a central molecule and all the surround-ing molecules in the crystal.E hkl ,i b ′is the incorporation energyof the impurity molecule on the {hkl }face,while E hkl ,i sl ′and E hkl ,i att ′are the slice and attachment energy of the {hkl }face with the impurity in symmetry position i ,respectively.Minimum change in the relative incorporation energy (i.e.,low ∆b )indicates where the impurities are most likely to incorporate.48,49The energy is a useful measure on the compat-ibility of the impurity with the host crystal lattice and has been successful in predicting an impurity-modified crystal morphology 47-52and thus used herein to assess the impact of the impurities on the purity of the crystals.Results and DiscussionCrystal pound 1exists in three distinct crystalline forms.Table 1summarizes the crystallographic data for each polymorph.All three crystal structures are rich in hydrogen bonds and are composed of sheets where it is observed that the crystal building block or growth unit for each modification is a centrosymmetric dimer interconnected by symmetrical N s H N t C interactions.In forms A and B,compound 1molecules are packed to form the centrosymmetric aggregate between the hydroxyl hydrogen andtheFigure 2.Powder X-ray diffraction patterns for a number of mixtures of form A and formB.Figure 3.Calibration curve for the degree of conversion of form A to form B using powder X-ray diffraction.Table 1.Crystallographic Data for Compound 1Polymorphsform Aform B form C crystal system triclinic monoclinic triclinic space group P 1hP 21/c P 1a (Å)10.614(2)10.488(7)9.5060(8)b (Å)13.419(4) 4.811(1)14.997(1)c (Å) 5.123(1)28.263(1) 5.276(1)R (Å)90.84(2)9098.00(1) (Å)95.52(2)91.23(2)101.76(1)γ(Å)88.98(3)90103.845(8)cell volume (Å3)726.1(3)1425(1)700.8(2)Z241F calc (g/cm 3) 1.41 1.436 1.461temp (K)293.2293.2293.2radiation CuK R CuK R CuK R wavelength 1.5418 1.5418 1.5418R 0.10160.06380.083R w0.17880.10630.1312∆b )E hkl b -E hkl ,i b ′)(E hkl sl +(1/2)E hkl att )-K i (E hkl ,i sl ′+(1/2)E hkl ,i att ′)Solution-Mediated Phase Transformation Crystal Growth &Design,Vol.5,No.4,20051431trifluoromethyl fluorine atoms (Figure 4a,b).In contrast,molecules in form C are organized in which an inter-molecular hydrogen bond is formed between the hy-droxyl hydrogen and the carbonyl oxygen atom of a neighboring molecule (Figure 4c).In form B,the fluorine atoms of the trifluoromethyl group in compound 1are disordered and are assigned a site occupancy factor (SOF)of 0.7/0.3as determined from refinement.In all three crystalline structures,there are two hydrogen bond donors,the amide hydrogen (N -H)and the hydroxyl hydrogen (O -H),within the molecule,and there are two hydrogen bond acceptors:for forms A and B,the cyano nitrogen (C t N)and the trifluoromethyl fluorine (CF 3),and for form C the cyano nitrogen (C t N)and the carbonyl oxygen (C d O).In addition,these donors and acceptors are involved in intramolecular hydrogen bonds with the exception of the trifluorometh-yl group.The hydrogen bonding interaction between the amide hydrogen and cyano nitrogen links the growthunit of each polymorph.Clearly,hydrogen bonding is an essential feature in the crystal structures of com-pound 1.The similar hydrogen bonding motifs in forms A and B suggest that disruptions in the hydrogen bonding sequence through the incorporation of an impurity might not only interfere with form A but also affect form B.On this basis,it might not be possible to stabilize the metastable A form by inhibiting the stable B form with an impurity that hinders the hydrogen bond formation;it would also likely disrupt the structure and the crystallization process of the metastable phase and possibly negate the suppression of the transformation to the more stable polymorph.Solubilities.The solubility curve of each form of compound 1in 2-propanol in the temperature range of 0to 40°C is shown in Figure 5.The solubilities show that form B and form C,and form A and form C are enantiotropic with a transition temperature at 20.1and 35.2°C,respectively.Below these crossover tempera-tures,form C is the most stable (i.e.,lowest solubility)with respect to the other form,whereas above these temperatures,the other polymorph is more stable.In contrast,the A and B form is a monotropic pair where form A is metastable relative to the B form.The solution-mediated transformation studies of form A to form B are carried out at 30°C to avoid the appearance of form C being mixed with form B since it has the lowest free energy (most stable phase)below 20°C despite the fact that the transformation rate from form B to form C is slow.Solution-Mediated Transformation.The solution-mediated phase transformation of compound 1com-prises three main steps:dissolution of the metastable phase,form A,nucleation of the stable phase,form B,and crystal growth of the stable form.The morphology of each form is shown in Figure 6.Both forms exhibit a platelike morphology,and thus it is difficult to identify the polymorph by the shape of the crystal or monitor the phase transformation by microscopy.Powder X-ray diffraction is employed to assess the rate of transforma-tion;polymorphic fractions are measured based on the differences between the powder patterns of each form (Figure 2).Characteristic peaks for both polymorphs are used to construct the calibration curve to quantitatively measure the composition change of the two polymorphs in the slurry (Figure 3).At certain time intervals,samples of the crystal slurry are removed and the conversion of form A to form B is monitored.Figure7Figure 4.Crystal packing of compound 1polymorphs:(a)form A viewed along the c -axis;(b)form B viewed down the b -axis;and (c)form C viewed parallel to the c -axis.Hydrogen bonds are represented by the aqua dashed lines.The circled areas indicate the growth units of eachform.Figure 5.Solubility of the three polymorphs of compound 1in 2-propanol.1432Crystal Growth &Design,Vol.5,No.4,2005Mukuta et al.shows the transformation behavior of compound 1in 2-propanol.In the first three experiments,the stirring speed is 300rpm and initial transformation of form A occurs after the first hour.However,when the degree of agitation is reduced to 150rpm,the time elapsed for the initial appearance of form B increases.Increasing agitation rate increases the crystallization kinetics (or the amount of secondary nucleation)of the stable phase,thus increasing the surface area of this phase and hence the transformation rate.The influence of structurally related impurities on the transformation rate is shown in Figure 8.Impurities RS1and RS4slightly retard the transformation rate,while with the addition of RS2and RS3transformation of the metastable A form to the stable form is hindered,particularly RS2,where a trace amount of form B is observed after 30h.Overall,the transformation behav-ior in the presence of RS1and RS4is very similar to the rate of the pure solution.To understand the effect of the doping level on the rate of transformation,two different impurity loadings (0.1and 0.5w/w%)for the two best inhibitors (RS2and RS3)were added to the solution,and the results are shown in Figure 9.The stabilization of the metastable modification as reflected in a decrease in the transformation rate is sensitive to the doping level.High impurity concentrations (e.g.,0.5w/w%)of RS2and RS3suppress the transformation to a greater extent than at low concentration consistent with the notion at low doping levels the nucleation rate and growth rate coefficients for the stable polymorph is similar to those in the absence of the impurities,whereas at high loadings the nucleation rate and growth rate coefficients decreases,resulting in an increase in transformation time.41The influence of seeding with form B in combination with the addition of the inhibitor RS2is shown in Figure 10.At low doping level and seeding,the transformation behavior resembles very closely to that in the absence of the impurity as conversion to the stable modification is completed after 2h.For high impurity loading and seeding with form B,small fractions of the stable B form,as detected from the powder X-ray patterns,are observed after 6h resulting in a 5-fold decrease in the initial appearance of the stable modification when compared to same doping level without seeding.InFigure 6.SEM images (500×)of form A (left)and form B (right)of compound 1.Figure 7.Transformation behavior of form A to form B at 30°C in2-propanol.Figure 8.Influence of impurities on the transformation behavior of compound 1at 30°C.Figure 9.Effect of impurity concentration on the transforma-tion behavior of compound 1at 30°C.Figure 10.Effect of seeding on the transformation rate of compound 1at 30°C in 2-propanol.Solution-Mediated Phase Transformation Crystal Growth &Design,Vol.5,No.4,20051433contrast,seeds that are ground together with a high level of RS2impurities reveal that the stabilizing effect of the impurity is reduced as full conversion to the stable form is observed after4h.The addition of seeds in the process clearly decreases the transformation time as a result of secondary nucleation.As the size of the seeds decreases such as in the case of grinding,higher surface areas of the seeds are expected,in turn,increasing the mass transfer and the overall growth rate of the stable polymorph.59Thus,the transformation rate is acceler-ated and the crystallization to form B is enhanced as the seeds act as a catalyst during the nucleation process. The initial appearance of form A and its subsequent disappearance and conversion to the stable B form follow Ostwald’s Law of Stages concerning the precipi-tation of the metastable modification followed by its transformation to the stable form.The driving force for the solution-mediated transformation is the differencein the free energy,specifically differences in the solubil-ity between the stable and the metastable modifications. Transformation to the less soluble B form occurs at the expense of the more soluble(or metastable)A form and the process progresses faster as the solubility difference between the two forms becomes greater.Full conversion is obtained when the solution reaches saturation with respect to the stable polymorph and the metastable modification is completely dissolved.The significant retardation effect of the RS2impurity is possibly due to its ability to inhibit the nucleation of form B,in turn,kinetically stabilizing the metastable phase,as reflected in the increase of the transformation time.The addition of the impurity most likely reduces the nucleation rate of form B,perhaps by disrupting and inhibiting the emerging nucleus.The crystal growth rate of form B might also be influenced by the impurity but not to a great extent considering that when small seed crystals were used in the presence of RS2,the trans-formation to form B proceeds much more rapidly compared with the addition of large form B seed crystals (Figure10),suggesting that crystal growth of the stable form in solution ensues despite the impurity.The prolonged induction period of the stable phase might also be explained by examining the impact the impuri-ties have on the solubility of compound1.Impurities can influence or alter the solubility of a solute,in turn, affecting the crystallization process.The higher the doping level or impurity loading,the more pronounced the effect becomes.Table2shows the effect of the structurally related impurities on the concentration of the stable B form of compound1in the absence and presence of the impurities.Although the impurities are molecularly similar to compound1,it is believed that the superior inhibitory impact of RS2might also be a result of the increase in the solubility of form B.This sudden enhancement leads to a smaller driving force for the transformation process,thus lowering the rate of transformation and stabilizing the metastable poly-morph.Differences in the molecular structure of the impurities lead to a different outcome of the transfor-mation behavior as each impurity molecule has unique modes of action and affects the crystallization process differently.The suppression of the stable B form with RS2as determined from powder X-ray diffraction quantification also reveals that the doping level is another factor that affects the conversion process and that a sufficient level of impurities is needed to hinder the formation of the stable modification.Impurity Incorporation.Structurally related im-purities may enter the host crystal lattice and replace the host molecule at lattice sites as a result of its molecular compatibility.Relative incorporation energies are calculated and used to evaluate the extent of the impurity incorporation.The molecular modeling ap-proach is a modification of Hartman and Perdok’s classical theory for predicting crystal morphology.58It requires the substitution of the host molecule with the impurity molecule and the calculation of attachment energies for both the pure and the impurity-modified crystal surfaces.Table3shows the relative incorpora-tion energies for compound1doped with the four structurally related impurities in each crystallographic position.The position of each impurity within the host lattice is optimized through a sequence of molecular mechanic and molecular dynamics simulations.The likelihood of an impurity incorporating into the crystal structure of form B of compound1can be indicated by low values of the relative incorporation energies.Crystal surfaces that have a minimum change in the energy are where the impurity will most likely to incorporate.Thus relative incorporation energies can be used to measure how easily an impurity can replace the host molecule on a given crystal plane.It can be seen that the impurity RS1has the lowest relative incorporation energiesTable2.Influence of Structurally Related Impurities on the Concentration(g/L)of Form B after the Solution-Mediated Phase Transformation at30°C in2-PropanolRS1RS2RS3RS4 0w/w%(pure) 3.860.1w/w% 3.77 3.98 3.80 3.730.5w/w% 3.82 3.93 3.87 3.801.0w/w% 3.71 4.00 3.77 3.81Table3.Relative Incorporation Energies(kcal/mol)for Various Crystallographic Planes of Compound1in the Presence of Four Structurally Related Impurities a crystal faces{hkl}Z RS1RS2RS3RS4 {100}1-2.883-7.405-4.345-14.4752-2.475-7.902-4.050-14.4533-2.419-7.608-3.985-15.9874-2.425-7.891-2.760-15.992 {102h}1-3.530-6.868-4.621-15.2882-3.314-7.720-4.458-15.2653-3.304-7.515-4.214-16.7974-3.307-7.711-2.848-16.802 {011}1-2.874-5.564-4.154-14.0682-2.479-6.898-4.540-14.1113-2.323-6.128-3.941-14.8824-2.567-6.877-3.823-14.999 {110)1-3.005-5.898-4.012-12.6852-2.401-5.986-3.128-12.1483-2.373-5.791-4.021-11.9864-2.046-5.974-2.526-12.633 {102}1-2.818-5.270-4.141-12.342-2.367-5.824-3.679-12.3173-2.340-5.528-4.521-13.8784-2.346-5.812-2.453-13.884 {211h}1-2.137-5.664-3.948-11.8242-1.874-8.374-4.081-11.123-1.864-5.736-3.454-11.5484-1.862-8.367-2.802-11.542a Z is the symmetry position in the unit cell:(1)Z)(x,y,z);(2)Z)(-x,y+1/2,-z+1/2);(3)Z)(-x,-y,-z);(4)Z)(x,-y +1/2,z+1/2).1434Crystal Growth&Design,Vol.5,No.4,2005Mukuta et al.。

材料科学英语

材料科学英语Materials Science is a multidisciplinary field that focuses on the study of the properties of matter and how they relate to its composition, structure, processing methods, and performance. It is an essential area of research that has a profound impact on the development of new materials and technologies.The field of materials science is vast and encompasses a wide range of materials, including metals, ceramics, polymers, semiconductors, and composites. Each of these materials has unique properties that can be manipulated and improvedthrough various processes. For instance, the strength and ductility of metals can be enhanced through heat treatmentand alloying, while the thermal and electrical properties of semiconductors can be fine-tuned for use in electronic devices.One of the key aspects of materials science is the understanding of the atomic and molecular structure of materials. This includes the arrangement of atoms in acrystal lattice, the presence of defects such as dislocations and grain boundaries, and the interactions between atoms. These structural features play a critical role in determining the mechanical, thermal, and electrical properties of materials.Material scientists also investigate the relationshipbetween processing methods and material properties. For example, the way a polymer is synthesized can affect its molecular weight, which in turn influences its strength and flexibility. Similarly, the method of sintering used to produce ceramics can impact their density and grain size, which are important for their mechanical and thermal performance.Innovation in materials science is driven by the need for materials with improved performance in various applications. This includes the development of lightweight materials for aerospace applications, high-temperature materials for engines, and biocompatible materials for medical implants. Researchers in this field are constantly seeking new ways to enhance the properties of existing materials or to create entirely new materials with unique characteristics.The study of materials science also involves the use of advanced analytical techniques to characterize materials at the atomic and molecular level. Techniques such as X-ray diffraction, electron microscopy, and spectroscopy are used to determine the structure, composition, and properties of materials. These tools are essential for understanding the fundamental principles that govern the behavior of materials and for guiding the development of new materials.In conclusion, materials science is a dynamic and essential discipline that plays a crucial role in the advancement of technology and the improvement of our daily lives. By understanding the complex relationships between the structure, processing, and properties of materials,scientists can continue to push the boundaries of what is possible and develop materials that meet the ever-evolving needs of society.。

铁电向列相液晶的光响应能力

第 38 卷第 7 期2023 年 7 月Vol.38 No.7Jul. 2023液晶与显示Chinese Journal of Liquid Crystals and Displays铁电向列相液晶的光响应能力林卓昂1，项颖1*，李佼洋2，蔡志岗2*，张文慧1，郝禄国1（1.广东工业大学信息工程学院，广东广州 510006；2.中山大学物理学院，广东广州 510275）摘要：以有机分子RM734为代表的液晶体系是一种具有铁电特性的向列相液晶。

为了探究其光刺激响应能力，本文对该液晶分子进行了紫外-可见吸收光谱测量以及UV光照实验。

结果表明，当处于低温铁电向列相时，液晶分子在357 nm 处有吸收峰，峰值吸光度高达1.74。

光照实验现象说明其在365 nm波段的UV光诱导下进行光降解反应的同时能够发生等温相变，从低温铁电向列相相变为高温传统向列相，这种相变行为是可重复的。

进一步实验结果显示，改变入射线偏振光的偏振方向或者光强大小能够调控相变速度。

具有光响应能力的铁电向列相液晶一定程度上具有可控性，这扩宽了铁电液晶的应用范围，为其光学器件的应用提供了新思路。

关键词：液晶；铁电特性；吸收光谱；等温相变；偏振方向中图分类号：O753+.2 文献标识码：A doi：10.37188/CJLCD.2023-0018Optical response of ferroelectric nematic liquid crystalsLIN Zhuo-ang1，XIANG Ying1*，LI Jiao-yang2，CAI Zhi-gang2*，ZHANG Wen-hui1，HAO Lu-guo1（1.School of Information Engineering， Guangdong University of Technology， Guangzhou 510006， China；2.School of Physics， Sun Yat-Sen University， Guangzhou 510275， China）Abstract： The liquid crystal system represented by the organic molecule RM734 is a nematic liquid crystal with ferroelectric properties. In order to explore its response to light stimulation， the UV-visible absorption spectrum measurement and UV illumination experiment were carried out on the liquid crystal molecule. The results show that when the liquid crystal molecule is in the low temperature ferroelectric nematic phase，there is an absorption peak at 357 nm， and the peak absorbance is up to 1.74. The experimental phenomenon of illumination shows that it can undergo isothermal phase transformation when conducting photodegradation reaction under the UV light induction of 365 nm wave band， from low temperature ferroelectric nematic phase to high temperature traditional nematic phase， and this phase transformation behavior is repeatable. Further experimental results show that changing the polarization direction or intensity of the incoming polarized light can control the phase transition speed.In general，ferroelectric nematic liquid crystals with optical 文章编号：1007-2780（2023）07-0862-08收稿日期：2023-01-16；修订日期：2023-03-10.基金项目：国家自然科学基金（No.11774070）；广东省自然科学基金（No.2022A1515010777）；广东省科技计划项目（No.2022A0505050072）；广东省重点领域研发计划项目（No.2020B0404030003）Supported by National Natural Science Foundation of China （No.11774070）； Natural Science Founda‑tion of Guangdong Province （No.2022A1515010777）； Science and Technology Planning Project of Guang‑dong Province （No.2022A0505050072）； Guangdong Provincial Key R&D Programme（No.2020B0404030003）*通信联系人，E-mail：xiangy@； stsczg@第 7 期林卓昂，等：铁电向列相液晶的光响应能力response ability are controllable to a certain extent，which broadens the application range of ferroelectric liquid crystals and provides new ideas for the application of their optical devices.Key words： liquid crystal； ferroelectric properties； absorption spectrum； isothermal transformation； polarization direction1 引言20世纪初，诺贝尔得主Max Born就对向列相液晶中可能存在铁电特性提出了设想［1］。

试剂介绍

1. Tris(dibenzylideneacetone)dipalladium(0)Tris(dibenzylideneacetone)dipalladium(0) or Pd2(dba)3 is an organometallic complex based on palladium and dibenzylideneacetone used in organic chemistry. It was discovered in 1970.Preparation and structure:It is prepared from dibenzylideneacetone and sodium tetrachloropalladate.[2] The complex has a dark purple/brown color, and, because it is commonly recrystalized from chloroform, it often as the adduct Pd2(dba)3.CHCl3.In tris(dibenzylideneacetone)dipalladium(0) the pair of Pd atoms are separated by 320 pm but are tied together by dba units.[3] The Pd(0) centres are bound to the alkene parts of the dba ligands.Applications:Pd2(dba)3 is used as a source of soluble Pd(0), particularly as a catalyst for various coupling reactions in which it undergoes oxidation to Pd(II). Examples of reactions using this reagent are the Negishi coupling, Suzuki coupling, Carroll rearrangement, Trost asymmetric allylic alkylation, as well as Buchwald–Hartwig amination.[4] A related Pd(0) complex is tetrakis(triphenylphosphine)palladium(0).References1.1.^ Takahashi, Y.; Ito, Ts.; Sakai, S.; Ishii, Y. (1970). "A novel palladium(0) complex; bis(dibenzylideneacetone)palladium(0)". Journal of the Chemical Society D: Chemical Communications: 1065. doi:10.1039/C29700001065.2.^ Encyclopedia of Reagents for Organic Synthesis, L.A. Paquette, Ed.: J. Wiley and Sons: Sussex, England, 19963.^ Pierpont, Cortlandt G.; Mazza, Margaret C. (1974). "Crystal and molecular structure of tris(dibenzylideneacetone)dipalladium(0)". Inorg. Chem. 13: 1891. doi:10.1021/ic50138a020.4.^ Hartwig, J. F. (2010). Organotransition Metal Chemistry, from Bonding to Catalysis. New York: University Science Books. ISBN 189138953X.The Negishi coupling is a cross coupling reaction in organic chemistry involving an organozinc compound, an organic halide and a nickel or palladium catalyst creating a new carbon-carbon covalent bond:[1][2]The halide X can be chloride, bromine or iodine but also a triflate or acetyloxy group with as the organic residue R alkenyl, aryl, allyl, alkynyl or propargyl.The halide X' in the organozinc compound can be chloride, bromine or iodine and the organic residue R' is alkenyl, aryl, allyl or alkyl.The metal M in the catalyst is nickel or palladiumThe ligand L in the catalyst can be triphenylphosphine, dppe, BINAP or chiraphosPalladium catalysts in general have higher chemical yields and higher functional group tolerance.The Suzuki reaction i s the organic reaction of an aryl- or vinyl-boronic acid with an aryl- or vinyl-halide catalyzed by a palladium(0) complex.[1][2] It is widely used to synthesize poly-olefins, styrenes, and substituted biphenyls, and has been extended to incorporate alkyl bromides.[3] Several reviews have been publishedThe reaction also works with pseudohalides, such as triflates (OTf), instead of halides, and also with boron-esters instead of boronic acids.Relative reactivity: R2-I > R2-OTf > R2-Br >> R2-ClFirst published in 1979 by Akira Suzuki, the Suzuki reaction couples boronic acids (containing an organic part) to halides. The reaction relies on a palladium catalyst such as tetrakis(triphenylphosphine)palladium(0) to effect part of the transformation. The palladium catalyst (more strictly a pre-catalyst) is 4-coordinate, and usually involves phosphine supporting groups.The 2010 Nobel Prize in Chemistry was awarded to Suzuki for his discovery and development of this reaction. In many publications this reaction also goes by the name Suzuki-Miyaura reaction. It is also often referred to as "Suzuki Coupling".Reaction mechanismThe mechanism of the Suzuki reaction is best viewed from the perspective of the palladium catalyst. The first step is the oxidative addition of palladium to the halide 2 to form the organopalladium species 3. Reaction with base gives intermediate 4, which via transmetalation[7] with the boron-ate complex 6 forms the organopalladium species 8. Reductive elimination of the desired product 9 restores the original palladium catalyst 1.Oxidative additionOxidative addition proceeds with retention of stereochemistry with vinyl halides, while givinginversion of stereochemistry with allylic and benzylic halides.[8] The oxidative addition initially forms the cis-palladium complex, which rapidly isomerizes to the trans-complex.[9]Reductive eliminationUsing deuterium-labelling, Ridgway et al. have shown the reductive elimination proceeds with retention of stereochemistry.[10] Relative reactivity of different metal complexes in the C-C reductive elimination was established: Pd(IV), Pd(II) > Pt(IV), Pt(II), Rh(III) > Ir(III), Ru(II), Os(II).ScopeRecent applications of the Suzuki–Miyaura cross-coupling reaction in organic synthesis has been summarized by Kotha and co-workers.[12] With a novel organophosphine ligand (SPhos), a catalyst loading of down to 0.001 mol% has been reported [13]:12.^ Recent applications of the Suzuki–Miyaura cross-coupling reaction in organic synthesis Sambasivarao Kotha, Kakali Lahiri and Dhurke Kashinath Tetrahedron 2002, 48, 9633-9695 doi:10.1016/S0040-4020(02)01188-213.^ Catalysts for Suzuki-Miyaura Coupling Processes: Scope and Studies of the Effect of Ligand Structure Timothy E. Barder, Shawn D. Walker, Joseph R. Martinelli, and Stephen L. Buchwald J. AM. CHEM. SOC. 2005, 127, 4685-4696 doi:10.1021/ja042491jThe Carroll rearrangement is a rearrangement reaction in organic chemistry and involves the transformation of a β-keto allyl ester into a α-allyl-β-ketocarboxylic acid.[1] This organic reaction is accompanied by decarboxylation and the final product is a γ,δ-allylketone. The Carroll rearrangement is an adaptation of the Claisen rearrangement and effectively a decarboxylative Allylation.Reaction mechanism The Carroll rearrangement (1940) in the presence of base and with high reaction temperature (path A) takes place through an intermediate enol which then rearranges in an electrocyclic Claisen rearrangement. The follow up is a decarboxylation. With palladium(0) as a catalyst, the reaction (Tsuji, 1980) is much milder (path B) with an intermediate allyl cation / carboxylic acid anion organometallic complexDecarboxylation precedes allylation as evidenced by this reaction catalyzed by tetrakis(triphenylphosphine)palladium(0) [3]:The Trost asymmetric allylic alkylation or Trost AAA or allylic asymmetric substitution is an organic reaction used in asymmetric synthesis.[1][2][3][4]In the reaction an allylic leaving group in an organic compound is displaced by a nucleophile while at the same time palladium is coordinated to the allyl double bond as a complex. A typical substrate in this reaction is an allylic compound with a good leaving group such as an acetate group. The reaction was originally developed with a catalyst based on palladium supported by the Trost ligand. The nucleophile can be a phenol, a phthalimide or simply water.Reaction mechanismZerovalent palladium is generated in situ from a palladium(II) source and a phosphine ligand such as the Trost ligand. The metal coordinates to the alkene forming a η2π-allyl-Pd0πcomplex. The next step is oxidative addition in which the leaving group is expelled with inversion of configuration and a η3π-allyl-PdII is created. The nucleophile then adds to the proximus or distal carbon atom of the allyl group regenerating the η2π-allyl-Pd0 complex. The palladium compound detaches from the alkene in the completion of the reaction and can start again in the catalytic cycle. The chirality stored in the ligand is transferred to the final product in one of the complexes formed.T he Buchwald-Hartwig reaction i n its original scope is an organic reaction describing a coupling reaction between an aryl halide and an amine in presence of base and a palladium catalyst forming a new carbon-nitrogen bond.The X in the aryl halide (Ar-X) can also be a triflate. The primary or secondary amine substituents can be any organic residue, the metal M in the reactions original scope is palladium and the ligand L can be a wide range of phosphines such as triphenylphosphine. Another regular catalyst ligand combination is tris(dibenzylideneacetone)dipalladium(0).[1] The base can be sodium bis(trimethylsilyl)amide or a tert-butoxide. The reaction is conceptually related to the Stille reaction and the Heck reaction and its scope extends to oxygen nucleophiles like phenols and carbon nucleophiles like malonates. It replaced to an extent the copper catalysed Goldberg reaction.The first example of a Buchwald - Hartwig amination reaction was realized in Kiev in 1985, by Professor Lev M. Yagupolskii et al. Polysubstituted activated chloroarenes and anilines underwent a C-N coupling reaction catalyzed by [PdPh(PPh3)2I] (1 mol%) in moderate yield:[2] This reaction type was developed independently by the groups of Buchwald and Hartwig. The reactants in the original Hartwig 1994 publication were a bromobenzene and a tributyltin amine:[3]The Buchwald 1994 reaction looked very similar:[4]In the second-generation Buchwald-Hartwig reaction, the aminostannane was replaced by a free amine and a strong base such as lithium bis(trimethylsilyl)amide: [5]The reaction mechanism for this reaction is outlined below:The Pd II catalyst 1 is reduced to the active Pd0 species 2 which is stabilized by a ligand L usually a phosphine. The catalytic cycle starts with species 3 lacking one ligand and the aryl halide 4 coordinates to palladium by oxidative addition to intermediate 5 which is in chemical equilibrium with dimeric species 5b. In the next step a halide atom is replaced by the nitrogen atom of the amine 6 to intermediate 7. The strong base 8 is required to abstract the proton from the amine towards 9. This intermediate gives either reductive elimination to the desired aryl amine 10 or undesired β-hydride elimination to the arene compound 11 and the imine 12. In either case the liberated Pd-L species starts a new catalytic cycle.ScopeOne study addressed the choice of solvent for this reaction[6] and found that with certain reactants aprotic polar solvents such as NMP(N-methylpyrrolidinone,N-甲基吡咯烷酮) and DMAC(N,N-dimethylacetamide, N,N-二甲基乙酰胺) promoted beta-elimination and the reaction was best carried out with aprotic apolar solvents such as m-xylene even though this solvent does not dissolve a tert-butoxide base.。

Crystal nucleation and growth of indomethacin polymorphs

Crystal nucleation and growth of indomethacin polymorphsfrom the amorphous stateVlassios Andronis 1,George Zogra®*School of Pharmacy,University of Wisconsin±Madison,425N.Charter Street,Madison,WI 53706,USAReceived 2July 1999;received in revised form 4October 1999AbstractThe e ect of temperature on the overall crystallization,and the crystal nucleation and growth rates of indomethacin polymorphs from the amorphous state were determined.Crystallization of amorphous indomethacin at temperatures close to or below its T g (42°C)favors the formation of the stable c polymorphic form,while crystallization at higher temperatures favors the formation of the metastable a -crystal form.Both the nucleation and growth rates for c -in-domethacin have maxima that coincide just above the T g of amorphous indomethacin.The nucleation rate for a -in-domethacin was found to have a maximum at 60°C,and the growth rate at 90°C.Assuming a temperature dependent crystal±amorphous interface free energy,good agreement was observed between the experimental nucleation data and the predictions of the classical theory of nucleation.The crystal±amorphous interface energy was higher for the c than for the a -indomethacin.Analysis of the crystal growth rates for both crystal forms showed that the mechanism of growth is by two-dimensional nucleation,but quantitative agreement with the theory was not found.The interface energy for the a -crystal form,obtained from the growth data was in very good agreement with the value obtained from the nucleation data.Ó2000Elsevier Science B.V.All rights reserved.1.IntroductionThe processing of crystalline solids for phar-maceutical use often leads to partially or fully non-crystalline materials with greatly altered chemical and physical properties relative to those expected from crystalline materials [1,2].We have been in-terested in those factors that in¯uence the crystal-lization of non-crystalline solids,and in particular we have studied the behavior of indomethacin,adrug that exists in two non-solvated monotropic polymorphic crystalline forms,as a model.It has been shown earlier that indomethacin crystallizes from the amorphous state well below its glass transition temperature,T g ,to produce the stable c -form,whereas at higher temperatures,the for-mation of the metastable a -form is predominant [3].It has also been shown that absorbed water vapor lowers the T g and enhances the overall crystallization rates,favoring the c -form at low water contents and the a -form at higher water contents [4].The dynamic properties of amorphous indomethacin as a function of temperature have been measured to establish the dependence of the viscosity and relaxation times on temperature [5,6].In order to gain a better understanding of the factors that govern crystallization ofamorphousJournal of Non-Crystalline Solids 271(2000)236±248/locate/jnoncrysol*Corresponding author.Tel.:+1-6082622991;fax:+1-6082623397.E-mail address:gzogra®@facsta (G.Zogra®).1Present Address:SmithKline Beecham Pharmaceuticals,1250S.Collegeville Road,Collegeville,PA 19426,USA.0022-3093/00/$-see front matter Ó2000Elsevier Science B.V.All rights reserved.PII:S 0022-3093(00)00107-1indomethacin under pharmaceutically relevant storage conditions,below and above T g,and to understand the basis for the already observed polymorph phase selectivity,in this study,in ad-dition to the overall crystallization rates,we have measured the crystal nucleation and growth rates as a function of temperature and analyzed the re-sults in the context of the available theories of crystal nucleation and growth.2.Experimental2.1.MaterialsIndomethacin(1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid)has two polymorphic modi®cations for which consistent melting tem-perature IR,NMR,and X-ray powder di raction data exist[7].Form c has a melting temperature, T m,of161°C,and a heat of fusion,D H f of110J/g. The a-form has a T m of155°C,a D H f of91J/g, and a higher aqueous solubility than the c-form [8].This is a monotropic system with the c-form being more stable than the a-form over the entire temperature range[3].Kistenmacher[9]deter-mined the crystal and molecular structure of the c-form.It crystallizes in space group P1(triclinic) with Z 2,and cell constants a 9X295#A,b 10X969#A,c 9X742#A,a 69.38°,b 110.79°,c 92.78°,and V 869X8#A3.The calculated density is1.37g/cm3;the experimental determined value is1.38g/cm3[3].The feature that dominates the crystal packing is the hydrogen bonding of the carboxylic acid group to form molecular dimers. The crystal structure of a-indomethacin was re-cently determined[10].It crystallizes in space group P21(monoclinic)with Z 6.The unit cell constants are a 5X462#A,b 25X310#A, c 18X152#A,a 90.00°,b 94.38°,c 90.00°, with V 2501#A3.The calculated density is1.43 g/cm3which agrees well with the experimentally determined value of1.40g/cm3[3].The asymmet-ric unit consists of three molecules with very dif-ferent conformations,with the third molecule hydrogen bonded to the molecular dimer formed by the remaining two molecules.Crystalline c-indomethacin was obtained with a chemical purity better than99.5%,determined with HPLC and melting point depression by DSC. It was further puri®ed by recrystallization from ethanol.The a-form of indomethacin was ob-tained in pure form by dissolving the c-form in ethanol at80°C;activated carbon was added and the solution was®ltered through a0X2l m®lter. Ultra pure water at room temperature was then added to the solution and the a-crystal form pre-cipitated quantitatively.The solid was removed by ®ltration and dried under vacuum.The procedure was repeated in triplicate.Amorphous indomethacin was prepared by melting the a-form of crystalline indomethacin powder in an aluminum weighing pan;the melt was kept at165°C for5min and then quench-cooled by immersion into liquid nitrogen.The re-sulting glass was found free of crystallinity using WAXS,and optical microscopy under cross po-larizers.No change in the purity of the indo-methacin glass was observed as a result of the melting and quenching.The amorphous sample was not ground before the experiments since we wanted to avoid as much as possible mechanical activation of the sample during grinding[11]. However since shattering of the glass during the quenching of the melt occurred,a form of mild mechanical stress was thus applied.During heating of dry amorphous indometha-cin in a DSC at a heating rate of1°C/min,the glass transition temperature T g was observed at42°C,a single crystallization exotherm occurred with onset at102°C and peak at110°C,and both crystalline forms crystallized from the melt.2.2.MethodsFor the determination of the overall crystalli-zation rates,amorphous indomethacin,prepared by quenching in liquid nitrogen was stored at0% relative humidity(maintained with P2O5)inside desiccators maintained in ovens at temperatures from20°C to60°C.A small quantity was with-drawn at various times and ground to a®ne powder immediately before determination of its crystallinity with WAXS[4].V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids271(2000)236±248237Nucleation rate measurements are best per-formed with a two-stage isothermal technique[12]; during the low temperature treatment nuclei are formed and during the second higher temperature treatment the existing nuclei are grown to ob-servable dimensions.The method is essential when the growth rate at the nucleation temperatures is low.In our case we observed that crystallites grew rapidly enough,so it was possible to use the single-stage isothermal technique[13,14].This method has the additional advantage that the isothermal growth rates can be measured simultaneously with the nucleation rate.In our case it also eliminated the complication that one polymorph might be nucleated at one temperature and the other poly-morph might grow during the development stage at another temperature.This was observed via WAXS in preliminary experiments with the two-stage technique.The single-stage isothermal technique can underestimate the crystal particle number density since some particles will always be too small for observation.However,it has been shown that the error in the determination of the steady state particle number density and nucle-ation rates is smaller than the error due to the statistical scatter of the data[14].For the determination of the crystal nucleation and growth rates,puri®ed a-crystal form was melted on pre-cleaned microscope slides,to form a solid®lm of approximately0.3mm thickness. Attention was paid to assure that the®lms were free of bubbles and that the procedure was per-formed at less than15%RH to minimize contact with water vapor.The slides were stored over P2O5 (0%RH)inside desiccators placed in ovens main-tained at di erent temperatures ranging from20°C to100°C.The samples were removed from their desiccators for microscopic examination every week,except with samples crystallizing very quickly or very slowly,where the sampling interval was adjusted accordingly.At the end of the ex-amination they were returned to the desiccators until the next sampling time,when the same slides were used again.Depending on the temperature, the samples were followed for times ranging from a few weeks to more than a year.The growing crystallites were viewed under cross polarizers with an optical microscope equipped with long working distance objective lenses.Depending on the size of the crystals,magni®cations from50to500´were used.A total of6±10images,for every sample at each time point,were recorded with a video cam-era attached to the microscope,and they were stored on videotape.The images were digitized before further analysis.The particle number den-sity(per unit area of the®eld of view)[15],and the largest particle size[16]were determined from image analysis of the digitized images.The particle number density per unit volume was calculated from the particle number density per unit area, and the depth of®eld(D f)of the lens that was used for data collection.The depth of®eld as a function of the wavelength of the light used k 500nm and the numerical aperture(NA)of the lens is given by the following equation[15]:D fk1ÀNA2ÀÁ1a2NA2X 1The D f used varied from0.029mm(5´objective) to0.00047mm(50´objective).Images of a cali-brated1-mm graticule were used for size calibra-tion at each magni®cation.From50to800 crystalline particles were counted and measured in each slide.In some cases preferential nucleation and growth appeared at the periphery of the®lms but these sites were not included in our analysis. The statistical error in N,as re¯ected in the stan-dard deviation,was10±20%depending on the number of crystals.Crystal form identi®cation with X-ray was performed,as previously de-scribed,on all of the samples at the end of the experiment.Propagation of errors was taken into account for data where applicable.3.ResultsThe isothermal crystallization of amorphous indomethacin at various temperatures is shown in Figs.1and2.It should be pointed out that the shear relaxation time for dry amorphous indo-methacin at30°C,estimated from viscoelastic data,is about four days[5].In this respect, therefore,the amorphous samples are believed to be in a fully relaxed equilibrium state before any238V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids271(2000)236±248detectable crystallization occurs.In Fig.1we present the results for samples stored at 20±40°C where only the c -crystal form appears,while inFig.2are given data for crystallization at 50°C and 60°C.At 50°C a mixture of both crystal forms appeared.The solid lines in Figs.1and 2are the non-linear ®t of the Kolmogorov±John-son±Mehl±Avrami (KJMA)equation [17]to the experimental data x t 1Àexp ÀK t Às n Y2where x t is the fraction transformed at time t ,K ,a constant depending on the nucleation (I )and growth (G )rate constants,s the induction time,and n is a constant related to the dimensionality of the transformation.Figs.3and 4show optical images for the c -and the a -crystal forms of indomethacin,re-spectively,crystallizing out of the melt.The c -crystal form grows as needles,eventually forming a polycrystalline array radiating from a single center,with a considerable amount of amorphous material between the thin needles.The a -crystal form grows as compact spherulites with very little amorphous content.The observed di erence in the morphologies of the two crystal forms growing from the melt enabled us to sep-arate their nucleation and growth rates at 50°C.Furthermore no change in morphology or crystal interconversion was observed for the time that the samples (especially the c crystal)were studied.Fig.5shows examples of crystal particle number densities per unit volume as a function of time.The slopes of the lines are the steady state nucleation rates.Fig.6shows examples of the crystal radius as a function of time for the samples of Fig.5.For both crystal forms the rate of ad-vance of the overall interface pro®le was measured for the largest crystals presented on the recorded images.As can be seen,the crystal radius varies linearly with time,the slope being the crystal growth rate.The nucleation and crystal growth rates at the other temperatures were obtained in the same manner and they are shown in Figs.7and 8.From Figs.7and 8we see that the maxima in the nu-cleation and growth rates of the c -form coincide just above T g ,whereas the maximum for the a -form is around 60°C for nucleation and 80°CforFig.1.Isothermal crystallization of dry amorphous indo-methacin to c -crystal form at 20°C (h ),30°C (s )and 40°C (n ).The lines are the ®t of the Avrami equation.Error bars repre-sent one standarddeviation.Fig.2.Isothermal crystallization of dry amorphous indo-methacin at 60°C (j )and 50°C (a -form (s ),c -form (d )).The lines are the ®t of the Avrami equation.Error bars represent one standard deviation.V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids 271(2000)236±248239Fig.4.Photomicrograph of the a -crystal form grow from the amorphousphase.Fig.3.Photomicrograph of the c -crystal form grow from the amorphous phase.240V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids 271(2000)236±248growth.This picture for the crystallization of a -indomethacin is consistent with what has been found for many materials;the nucleation rate has a maximum above T g and the growth rate is fur-ther displaced at higher temperatures somewhere between T g and T m [18,19].The crystallization behavior of the c -form however,is not as clearly understood at thispoint.Fig.7.Nucleation rate for amorphous indomethacin as a function of temperature,(h )c -form,(j )a -form.Error bars represent one standarddeviation.Fig.5.Nuclei number density as a function of time at 40°C (s ),and 60°C (h ).The slopes of the lines are the steady state nucleation rates.Error bars represent one standarddeviation.Fig.8.Growth rate for amorphous indomethacin as a function of temperature,(j )c -form,(h )a -form.Error bars represent one standarddeviation.Fig.6.Crystal radius as a function of time at 40°C (s ),and 60°C (h ).The slopes of the lines are the steady state growth rates.Error bars represent one standard deviation.V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids 271(2000)236±2482414.Discussion4.1.Analysis of the nucleation rates of dry amor-phous indomethacin as a function of temperature The steady state rate of homogeneous crystal nucleation in a single component system is given for a spherical nucleus,by the classical expression [20,21],I ATgexpÀ16p r33kT D G2VY 3where A is a constant,g the shear viscosity,r the crystal±amorphous interfacial energy,D G V the change in Gibbs free energy per unit volume for the transformation from the amorphous to the crystalline phase,and for the spherical nuclei c is a constant with value5.333.The prefactor A has the form[22]A 2N V V1a3k3p k3rkT1a2Y 4where N V is the number of molecules of the crystal phase per unit volume,V the volume of one mol-ecule,k the jump distance for a molecule at the interface during the process of nuclei formation, and k is the Boltzmann constant.The viscosity of amorphous indomethacin,in the temperature range of interest,was found to follow the VTF equation[5]g Pa s2X7Â10À7exp2281TÀ256X 5The di erence in free energy D G V between the liquid and crystalline phase as a function of tem-perature for crystalline and amorphous indo-methacin in the absence of heat capacity data was calculated from the Ho man equation[23]D G V D H f T mÀTTT2mY 6where D H f is the heat of fusion and T m is the melting point.This is an approximation,but the equation has been found to accurately predict the D G V for small molecular weight organic glass formers for which heat capacity data exist[24].D G V was also determined with the Thompson±Spaepen equation[24]since T0had been deter-mined for amorphous indomethacin[5].This equation essentially gave the same results as the Ho man equation.In Fig.9the D G V values for the two polymorphs of indomethacin are presented. We can see that the system is indeed monotropic as was proposed earlier[3],in that the c-crystal form has a larger D G V and thus is the stable form up to a virtual transition temperature of190°C.The two crystal forms however,are very close energetically at the temperatures where the crystallization experiments were performed.In Fig.10the plot of ln I g a T vs1a T D G2V [21±25]is shown for the two crystalline forms of indo-methacin.The slopes are negative as is theoretically predicted from Eq.(3),and from these the liquid±crystal interface energy r was calculated to be0.027 J/m2for the c-crystal form and0.017J/m2for the a-crystal form.From the y-axis intercept the pre-exponential factor A in Eq.(3)was found to have a value of4X0Â1051(N/km5)for the c-crystal form and1X0Â1027(N/km5)for the a-crystal form.In comparison the calculated theoretical values for A are1X5Â1031for the c-crystal form and4X4Â1030 for the a-crystal form.The theoretical values of A were calculated by using the value of thecrystalFig.9.The predictions of the Ho man equation for the two crystal forms of indomethacin.242V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids271(2000)236±248amorphous interface free energy obtained from Fig.10.In addition the value of the jump distance k was determined by assuming that k 3 V unit cell ,where V unit cell is the unit cell volume which is known for both crystal forms from single crystal data.The value of c that was used to compute A is9X 5#Afor the c -crystal form,and 13X 6#A for the a -crystal form.The value of the prefactor A is quite sensitive to the exact value of k that is used for thecalculation;if a value of 1#Ais assumed for k the value of A is 3orders of magnitude larger.Whereas for the a -crystal the theoretical value of A is within the error of the extrapolation,for the c -crystal form the theoretical value of A is smaller than the experimental A ,beyond the error of the extrapolation.The possible reasons for the di erence between the experimental and theoreti-cal values for A have been discussed in detail in the literature [21,26,27],with a temperature-dependent liquid±crystal interface energy most often used to explain the discrepancy between the experimental and theoretical values of the prefactor A [22].This has been shown [22]not to be inconsistent with the apparent linearity observed in ing the known values for I ,g ,A ,and D G V the value of r was varied at each temperature until the experi-mental nucleation rates agreed with the theoretical ones and the results are shown in Fig.11for bothcrystal forms.First we note that the value of r for the a -crystal form is fairly constant and very similar for the two procedures,whereas the values of r for the c -crystal interface in Fig.11are smaller than the value calculated from Fig.10.This is probably because A determined in Fig.10is much closer to the theoretical value for the a -crystal form.The temperature-dependent r for the c -crystal form follows the equationr c 0X 85 0X 06T mJ Âm À2ÀÁ7 while that for the a -crystal form follows the equationr a 22X 02À0X 02TmJ Âm À2ÀÁX 8 Note that for the c -crystal±liquid interface at thenucleation temperatures the results imply a large negative interface entropy term,whereas for the a -crystal interface a small positive interface entropy term is implied.The negative entropy term ob-served for the c -crystal is consistent with theoret-ical models for the interface that suggest that the interface free energy is primarily entropic in nature [28].This could take place due to a sharpening of the liquid crystal interface as the temperature is increased.To the contrary the a-crystal±liquidFig.11.The temperature dependent interface energy r for the two crystal forms of indomethacin,c -form (h ),a -form (s ).Data ®t with one adjustableparameter.Fig.10.Plot of the nucleation rates according to Eq.(9),(h )c -form,(s )a -form.Error bars represent one standard deviation.V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids 271(2000)236±248243interface energy seems to be primarily energetic in nature,suggesting that it possibly becomes more di use as the temperature increases.We will mention here that the interface free energy actually depends on the orientation at the interface,and assuming non-spherical nuclei,it will have di erent values for the di erent nuclei faces.In this respect,the value of r that is obtained assuming a spherical nucleus is an average value. An analysis of the nucleation data for c-indo-methacin was also performed,according to the model of Rowlands et al.[21],assuming that the critical nuclei is orthorhombic and has the same dimensions as the unit cell of c-indomethacin.In this case the nucleation rate equation will take the form of Eq.(3),with the constant c having a value of10.245,r is again an average interface free energy.For c-indomethacin the value of r assuming an orthorhombic nucleus was determined from the nucleation data to be0.022J/m2;for a comparisonthe value of r obtained under the assumption of a spherical nucleus was0.027J/m2.Following Row-landsÕmethod of data analysis,the3components of the interface energy were estimated to have values of0.020,0.021and0.024J/ing a value of 0.020J/m2for r,the prefactor A calculated from Eq.(4)has a value of1X27Â1031.Following this analysis we would say that small di erences in the exact value of r,due to an assumption of sphericity, that is used to calculate A would not be enough to reconcile theory and experiment in our case. Based on the values of r from Eqs.(7)and(8), the values of the free energy barrier to nucleation D GÃfor the two crystal forms of indomethacin were calculated and are shown in Fig.12.In the temperature range of our experiments D GÃis well within the limits of20±60KT corresponding to explosive and zero nucleation rates,respectively [20].In the same®gure the activation energy for the viscosity of dry amorphous indomethacin is also included for comparison.4.2.Analysis of the growth rates of dry amorphous indomethacin as a function of temperature Three theoretical models have been used to describe crystal growth of glass forming materials;normal or continuous,spiral or dislocation,and two-dimensional nucleation.Their common mathematical form is summarized[29]with a general equation for crystal growth as follows:UCTwg1ÀexpÀD G VkT!Y 9where C is a constant,w a function of D G V de-pending on the mechanism of growth,g the vis-cosity,and D G V is the free energy di erence between the parent and product phase.The term inside the parentheses in Eq.(9)was calculated to be approximately1for indomethacin,in the tem-perature range of the experimental data.The®rst goal of the analysis of the growth rates is to establish the mechanism of growth.Deter-mination of the mechanism of crystal growth by graphical means is however not trivial as has been shown in the literature[30,31].This is more so at high undercooling when all modes of growth show similar temperature dependence[29].The classic plot[29]of ln U g vs the degree of supercooling D T is shown in Fig.13for indomethacin.As shown,the data are well represented by two straight lines each corresponding to the a-and c-crystal forms of indomethacin.This behavior is theoretically predicted to result fromcrystal Fig.12.Summary of the activation energies of amorphous indomethacin during crystallization.244V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids271(2000)236±248growth by the surface nucleation mechanism [29].For most materials with high entropies of fusion like indomethacin 11R ,growth by two-di-mensional nucleation has been found to be appli-cable even though the true behavior of the interface is likely more complex [31].According to this model [32],two-dimensional nuclei appear on the smooth and dislocation-clean crystal surface as a result of thermal ¯uctuations,and laterally propagate to form a new crystalline layer.The continuous formation of new layers results in the crystal surface traveling normal to itself.For growth by two-dimensional nucleation w in Eq.(9)is given by [33]w expÀp r 2kD G V kT Y 10 where the derivation of the critical work to form a two-dimensional nucleus is analogous to a similar calculation for spherical nuclei,k is the height of the two-dimensional nuclei,and the interface en-ergy r is the same as for crystal nucleation.For the generally applicable case,for which the lateral propagation rate of the nuclei has to be accounted (large crystal case),the constant C in Eq.(9)is given by [31]C 1X 12kN 1a 3s 3p k 3k 5a 3Y11where N s is the number of molecules per interface unit area.In Fig.14the plot of ln U g a T vs 1a T D G V is shown for the two crystalline forms of indometh-acin.The values used for g and D G V are the same as for the analysis of the nucleation data.The data are again characterized by two straight lines with di erent negative slopes corresponding to the two polymorphs of indomethacin.This plot also sug-gests growth by two-dimensional nucleation for both crystal forms.From the slopes in Fig.14it is possible to calculate the interface energy for the two crystal forms based on Eq.(9).The calculation is complicated because k is not known;however assuming that k 3 V unit-cell ,we found a value of 0.148J/m 2for the c -crystal form and 0.020J/m 2for the a -crystal form.The value of r for the a -crystal form obtained from the growth rates is in excellent agreement with the interface energy cal-culated from the nucleation rate.This further suggests that growth by two-dimensional nucle-ation takes place for the a -indomethacin.To the contrary,the value for c -indomethacin determined from the growth data is much higher by aboutanFig.14.Plot of the growth rates according to Eq.(9),(h )c -form,(s )a -form.Error bars represent one standarddeviation.Fig.13.The growth rate of amorphous indomethacin corrected for the viscosity as a function of supercooling D T T m ÀT ,(h )c -form,(j )a -form.Error bars represent one standard devia-tion.V.Andronis,G.Zogra®/Journal of Non-Crystalline Solids 271(2000)236±248245。

230种晶体学空间群的记号及常见矿石的名称、分子式与所属晶系【范本模板】

230种晶体学空间群的记号Symbols of the 230 Crystallographic Space Groups晶系（Crystal system)点群(Point group）空间群（Space group）国际符号(HM）圣佛利斯符号（Schfl.）三斜晶系1 C1P1C i P单斜晶系2 P2 P21 C2m P m P c C m C c2/m P2/m P21/m C2/m P2/c P21/C C2/c正交晶系222 P222 P2221 P21212 P212121 C2221 C222 F222 I222 I212121 mm2Pmm2 Pmc21 Pcc2 Pma2 Pca21 Pnc2 Pmn21 Pba2 Pna21Pnn2 Cmm2 Cmc21 Ccc2 Amm2 Abm2 Ama2 Aba2 Fmm2Fdd2 Imm2 Iba2 Ima2mmmPmmm Pnnn Pccm Pban Pmma Pnna Pmna Pcca PbamPccn Pbcm Pnnm Pmmn Pbcn Pbca Pnma Cmcm CmcaCmmm Cccm Cmma Ccca Fmmm Fddd Immm Ibam IbcaImma四方晶系4 P4 P41 P42P43 I4 I41P I4/m P4/m P42/m P4/n P42/n I4/m I41/a422P422 P4212 P4122 P41212 P4222 P42212 P4322 P43212 I422I41224mmP4mm P4bm P42cm P42nm P4cc P4nc P42mc P42bc I4mmI4cm I41md I41cd2mP 2m P2c P 21m P21cPm2Pc2P b2 P n2Im2I c2 I 2m I 2d4/mmmP4/mmm P4/mcc P4/nbm P4/nnc P4/mbm P4/mnc P4/nmm P4/ncc P42/mmcP42/mcm P42/nbc P42/nnm P42/mbc P42/mnm P42/nmc P42/ncm I4/mmm I4/mcmI41/amd I41/acd三方晶系3 P3 P31P32R3P R32 P312 P321 P3112 P3121 P3212 P3221 R32 3m P3m1 P31m P3c1 P31c R3m R3cm P1m P 1c P m1 P c1 R m R c六方晶系6 P6 P61P65P62P64P63P6/m P6/m P63/m622 P622 P6122 P6522 P6222 P6422 P6322 6mm P6mm P6cc P63cm P63mcm2P m2 P c2 P 2m P2c6/mmm P6/mmm P6/mcc P63/mcm P63/mmc立方晶系23 P23 F23 I23 P213 I213m Pm3 Pn3 Fm3 Fd3 Im3 Pa3 Ia3432 P432 P4232 F432 F4132 I432 P4332 P4132 I41323m P 3m F 3m I3m P3nF3cI3dm mPm m Pn n Pm n Pn m Fm m Fm c Fd mFdcIm mIa d空间群是点对称操作和平移对称操作的对称要素全部可能的组合。

晶型转变的影响因素

影响晶型转变的因素众所周知,构造决定性质,而对于晶体来说，当外界条件变化时，晶体构造形式发生改变，碳、硅、金属的单质、硫化锌、氧化铁、二氧化硅以及其他很多物质都具有这一现象，所以本文通过查阅文献举例说明影响晶型的一些因素，主要有温度、压力、粒度和组成。

一、温度温度对晶型影响比拟复杂，当温度升高时，晶体中的分子或某些离子团自由旋转，取得较高的对称性，而改变晶体的构造。

下面举例说明：(1) BaO·Al2O3·SiO2(BAS)系微晶玻璃的主晶相为钡长石。

钡长石主要的晶型有单斜钡长石(monoclinic celsian)、六方钡长石( hexa celsian)和正交钡长石(orthorhombic celsian),三者的关系如图1所示:Fig. 1 The phase transformation of celsian由图中我们可以看到:六方钡长石膨胀系数高,为8. 0×10-6/℃,而且在300℃左右会发生其向正交钡长石的可逆转变,转变过程中伴随着3-4%的体积变化。

(2)当预热温度小于400℃时，反响所得到的产物氧化铝为非晶态的A12O3。

非晶A12O3。

在热力学上是一种亚稳状态，所以它有向晶态转化的趋势。

当温度不够高时，非晶A12O3中的原子的运动幅度较小，同时晶化所必不可少的晶核的形成和生长都比拟困难，因此非晶态向晶态的转化就不易。

为研究所制备的非晶A12O3。

向晶态Al2O3转变的规律，我们把在300℃时点火得到的非晶A12O3 进展了锻烧处理，结果见表2:Fig.1 XRD Patterns of Produets kept for 1.5h at 700一900℃Fig.2 XRD Pattems of produets kept for o.5h at l000一l200℃Fig.3 XRD Pattems of produets kept for o.5h at l000℃and l200℃Fig.4 XRD Pattems of produets kept for different time at l000℃Fig.5 XRD Pattems of produets kept for different time at 1100℃从图1中可以看到，非晶态的氧化铝经700、800、900℃锻烧1.5h后，氧化铝从非晶态转变为r-A12O3，并且随着温度的升高r- A12O3。

卤键弱作用浅谈

卤键弱作用浅谈王亚琴;邵群【摘要】Halogen bonding, a noncovalent, int ermolecular weak interaction analogues to hydrogen bonding, exists between σ antibonding orbital of halogen atoms and atoms with lone-pair electron and πelectron system, which exerts unique effect in the field of desigh of functional materials and biomedicine. In this paper, the interaction essence of halogen bonding was simply introduced, the developing history of halogen bonding was elaborated and the basic character of halogen bonding was depicted, looking forward to much more comprehension toward halogen bonding.%卤键是与氢键相似的一种分子间非共价作用，存在于卤原子的σ反键轨道与具有孤电子对的原子或π电子体系之间，在功能材料与生物药物设计方面发挥了独特作用。

介绍卤键的作用本质，阐述卤键发展简史，并描述卤键的基本特征。

【期刊名称】《淮南师范学院学报》【年(卷),期】2015(000)005【总页数】3页(P80-82)【关键词】卤键;非共价作用;碘三/碘五负离子【作者】王亚琴;邵群【作者单位】安徽建筑大学材料与化学工程学院，安徽合肥 230022;安徽建筑大学材料与化学工程学院，安徽合肥 230022【正文语种】中文【中图分类】O69弱相互作用是自然的或人工合成的受体，其与底物之间的识别作用基础。

蛋白质结晶方法大总结

蛋白质结晶方法大总结1.1结晶方法(Crystallization Techniques)1.1.1分批结晶(Batch Crystallization)这是最老的最简单的结晶方法，其原理是同步地在蛋白质溶液中加入沉淀剂，立即使溶液达到一个高过饱和状态。

幸运的话，不需进一步处理即可在过饱和溶液中逐渐长出晶体。

一个用于微分批结晶的自动化系统已被Chayen等人设计出(1991，1992)，其微分批方法中，他们在1-2. l包含蛋白质和沉淀剂的液滴中生长晶体。

液滴被悬浮在油(如石蜡)中，油的作用是作为封层以防止蒸发，它并不干扰普通沉淀剂，但是干扰能溶解油的有机溶剂(Chayen, 1997; see also Chayen, 1998)。

1.1.2液-液扩散(Liquid — Liquid Diffusion)这种方法中，蛋白质溶液和含有沉淀剂的溶液是彼此分层在一个有小孔的毛细管中，一个测熔点用的毛细管一般即可(如图1.2)。

下层是密度大的溶液，例如浓硫酸铵或PEG溶液。

如果有机溶剂如MPD被用作沉淀剂，它会在上层。

以1：1混合，沉淀剂的浓度应该是所期最终浓度的二倍。

两种溶液(各自约5P l)通过注射器针头导入毛细管，先导入下层的。

通过一个简易的摇摆式离心机去除气泡。

再加入上层，进而两层之间形成一个明显的界面，它们会逐渐彼此扩散。

Garc'?a-Ruiz and Moreno (1994) 已经发展液-液扩散技术至针刺法。

蛋白质溶液通过毛细力被吸入狭窄的管中，管的一端是封闭的。

接着，开放端被插入置于小容器的凝胶中，凝胶使得管竖直，蛋白质溶液与凝胶接触。

含有沉淀剂的溶液被倒在凝胶上，整个装置被保存于封闭的盒子以防蒸发。

沉淀剂通过凝胶和毛细管的扩散时间可以由毛细管插入凝胶的深度控制，从而蛋白质溶液中即可形成过饱和区域，毛细管底部高而顶部低。

这也可作为一个筛选最佳结晶条件的额外信息。

1.1.3蒸气扩散(Vapor Diffusion)1.1.3.1悬滴法(The Hanging Drop Method)这种方法中，在一个硅化的显微镜盖玻片上通过混合3-10P l蛋白质溶液和等量的沉淀剂溶液来制备液滴。

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

Crystal and molecular structure of three biologically active nitroindazolesPilar Cabildo a ,Rosa M.Claramunt a ,⇑,Concepción López a ,M.Ángeles García a ,Marta Pérez-Torralba a ,Elena Pinilla b ,M.Rosario Torres b ,Ibon Alkorta c ,JoséElguero caDepartamento de Química Orgánica y Bio-Orgánica,Facultad de Ciencias,UNED,Senda del Rey 9,E-28040Madrid,SpainbDepartamento de Química Inorgánica I,CAI de Difracción de Rayos-X,Facultad de Ciencias Químicas,Universidad Complutense de Madrid,28040Madrid,Spain cInstituto de Química Médica,CSIC,Centro de Química Orgánica Manuel Lora-Tamayo,Juan de la Cierva 3,E-28006Madrid,Spaina r t i c l e i n f o Article history:Received 7September 2010Received in revised form 13October 2010Accepted 13October 2010Available online 20October 2010Keywords:NOSIndazolesHalogen bondHydrogen bonding NMRDFT calculationsa b s t r a c t3-Bromo-1-methyl-7-nitro-1H -indazole (1),3-bromo-2-methyl-7-nitro-2H -indazole (2)and 3,7-dinitro-1(2)H -indazole (3)have been synthesized and characterized by X-ray diffraction,13C and 15N NMR spec-troscopy in solution and in solid-state.The dihedral angles obtained in the crystal structures are in good agreement with the molecular parameters calculated using DFT B3LYP calculations employing the 6-311++G(d,p)basis pounds 1and 2present intermolecular halogen bonds between the bromine and the oxygen atoms of the nitro group and in compound 3inter-and intramolecular hydrogen bonding exists.Ó2010Elsevier B.V.All rights reserved.1.IntroductionC -nitroindazoles unsubstituted on the N atom,particularly 7-ni-tro derivatives,are one the most potent families of nitric oxide syn-thase (NOS)inhibitors.These enzymes catalyze the oxidation of L -arginine to L -citrulline and nitric oxide (NO),a molecule that plays an important role in the regulation of blood pressure,neuro-transmission,and the immune response [1].We have been actively working on these and other indazoles in two directions:ﬁrst,in their structural aspects related to N–H ÁÁÁN hydrogen bonds and prototropic tautomerism [2–6];second,in their biological proper-ties [7–9].We will describe in this paper the structure and spectroscopic properties of three 7-nitroindazole derivatives (Scheme 1):3-bro-mo-1-methyl-7-nitro-1H -indazole (1),3-bromo-2-methyl-7-nitro-2H -indazole (2)and 3,7-dinitro-1(2)H -indazole (3)(1H -tautomer 3a and 2H -tautomer 3b ).The three compounds are known but their synthesis has been reported in several papers not citing comprehensively the litera-ture.The starting material is commercial 7-nitro-1H -indazole (4)(Scheme 2).Bromination in acetic acid to afford 5was reported by Auwers and Demuth in 1927[10].Treatment of 4with methyl sulfate in basic conditions yields both N -methyl isomers 6and 7that can be easily separated [11–13].Bromination of 6and 7affords 1and 2[11,12].The same compounds are obtained by methylation of 5resulting in a 70/30ratio of 1/2[12].With slightly different conditions,only 1was obtained [14,15].3,7-Dinitro-1(2)H -indazole (3)was ﬁrst reported by Habraken and Cohen-Fernandes in 1971in a two-step procedure through the rather unstable 2-nitro derivative 8[16].Compound 3has been prepared two more times by Wrzeciono,but always with the same proce-dure [17,18].2.Results and discussion 2.1.X-ray structuresAn X-ray study of compounds 1,2and 3has been carried out.Figs.1–3show the molecular structure for the three compounds.In all cases,the indazole rings are almost planar including the nitro groups in the best least-square plane for 2and 3(maximum dihe-dral angle about 7°),while for 1the dihedral angle is about 30°.For 1and 2intermolecular halogen bonding [19,20]between the bromine and the oxygen atoms of the nitro group led to chains parallels to axes c and a ,respectively (Figs.4and 5).In the case of 1the interaction involves only one O atom while in the case of 2the halogen bond is bifurcated (three-centered)and both O atoms of the nitro group contact with the Br atom.Both situations,the ﬁrst one more common,have been described in the literature [21–23].0022-2860/$-see front matter Ó2010Elsevier B.V.All rights reserved.doi:10.1016/j.molstruc.2010.10.023Corresponding author.Tel.:+34913987322;fax:+34913988372.E-mail address:rclaramunt@ccia.uned.es (R.M.Claramunt).In compound 3bifurcated inter and intramolecular hydrogen bonds form zig-zag chains parallels to axis a (Fig.6).The existence of bifurcated (three-centered)hydrogen bonds had also been re-nuclei have been straightforward and are in agreement with liter-ature data reported for other indazoles [28–30].The experimental CPMAS NMR spectra reported in Fig.7de-ORTEP plot (30%probability for the ellipsoids)of 1showing the labeling asymmetric unit.Fig.2.ORTEP plot (30%probability for the ellipsoids)of 2showing the labeling of the asymmetric unit.76P.Cabildo et al./Journal of Molecular Structure 985(2011)75–81are in the plane of the ring(dihedral angles=0°).These observa-tions coincide with those reported in the crystallographic section.2.3.2.Energies[B3LYP/6-311++G(d,p)]It is well known that in indazoles1H-tautomers(benzenoid)are more stable than2H-tautomers(quinonoid)[31].This is also the case for compound3where1H(3a)is42.5kJ molÀ1more stable than2H(3b).The same applies to the isomerism of N-substituted derivatives and so the1-methyl isomer1is19.2kJ molÀ1more sta-ble than the2-methyl isomer2.2.3.3.NMR[GIAO/B3LYP/6-311++G(d,p)]The absolute shieldings(r,ppm)provided by the GIAO calcula-cases,the difference exp.–calc.is betweenÀ15andÀ20ppm,as we have already reported(À20ppm[34]).As we have calculated both tautomers of3,in Fig.8are reported the signals most sensitive to tautomerism.Only the chemical shifts of3a are consistent with the experimental data reported in Tables 2and3,those of3b being rather different.This is the result ex-pected both from energy considerations and from the X-ray struc-the solid-state,where only one tautomer is found solution data indicate that a low amount,if any,ofpresent.A linear combination of the calculatedand3b(6%)afford values very close to the experimentalConclusionsSingle-crystal X-ray diffraction analyses indicate thatcompounds1,2and3crystallize in the orthorhombic monoclinic P2(1)/c and orthorhombic P2(1)2(1)2(1)spaceFig.3.ORTEP plot(30%probability for the ellipsoids)of3showing the labelingthe asymmetric unit.Dotted lines are used to express the intramolecular hydrogenbond.Fig.4.View along the b axis showing the Br–O interactions in compound1.View along the b axis showing the Br–O interactions in compoundrespectively.There is an excellent agreement between experimen-tal (both solution and solid-state)and theoretically calculated 13C and 15N NMR chemical shifts,save for the C-3chemical shifts in compounds 1and 2.DFT calculations predict that the 1-methyl iso-mer 1is more stable than the 2-methyl one 2in 19.2kJ mol À1,and from the two tautomers 1H-and 2H-in compound 3,the ﬁrst form is stabilized over the latter in about 42.5kJ mol À1.4.Experimental section 4.1.ChemistryMelting points for compounds 1–3were determined by DSC on a Seiko DSC 220C connected to a Model SSC5200H Disk Station.Thermograms (sample size 0.003–0.0010g)were recorded at the scanning rate of 2.0°C min À1.Thin-layer chromatography (TLC)was performed with Merck silica gel (60F254).Compounds were detected with a 254-nm UV lamp.Silica gel (60–320mesh)was employed for routine column chromatography separations with the indicated eluent.3-Bromo-7-nitro-1H -indazole (5)was prepared according to the published procedure [12].4.1.1.3-Bromo-1-methyl-7-nitro-1H-indazole (1)and 3-bromo-2-methyl-7-nitro-2H-indazole (2)In a round-bottomed ﬂask equipped with reﬂux condenser,3-bromo-7-nitro-1H -indazole (5)(0.63g,2.6mmol)was dissolved in dry methanol (25mL).Then,sodium methoxyde (0.18g,3.3mmol)and 0.55g of methyl iodide (0.24mL,3.9mmol)were added.The mixture was heated to reﬂux for 2days and then the solvent was removed under reduced pressure.Water (30mL)was added and the residue was extracted with chloroform (3Â45mL).The organic layers were combined,dried (Na 2SO 4),and concentrated to afford a crude solid formed mainly by the two isomers.After silica gel chromatography with (hexane/ethyl acetate 30:1),1was obtained ﬁrst (0.24,37%)and increasing to 1:1to afford 2(0.29,44%);m.p.(1):161.1°C (160–162°C)[12];m.p.(2):200.5°C (194–196°C)[12].(1)1H NMR (DMSO-d 6)d 8.28(dd,3J =7.9,4J =0.7,1H,H6),8.03(dd,3J =7.9,4J =0.7,1H,H4),7.43(dd,3J =3J =7.9,1H,H5),4.13(s,3H,CH 3);(2)1H NMR (DMSO-d 6)d 8.35(dd,3J =7.9,4J =0.8,1H,H6),8.02(dd,3J =7.9,4J =0.8,1H,H4),7.31(dd,3J =3J =7.9,1H,H5),4.24(s,3H,CH 3).4.1.2.3,7-Dinitro-1H(2H)-indazole (3)This compound was prepared according to Ref.[16]and ob-tained as a yellow solid.M.p.221.8°C;m.p.220°C [16].1H NMR (CD 3CN)d 12.83(br s,1H,NH),7.65(t,3J =8.0,1H,H5),8.48(d,3J =7.9,1H,H6),8.62(d,3J =8.1,1H,H4).4.2.NMR spectroscopySolution spectra were recorded at 300K on a Bruker DRX 400(9.4T,400.13MHz for 1H,100.62MHz for 13C and 40.56MHz for 15N)spectrometer with a 5-mm inverse detection H–X probe equipped with a z -gradient coil for 1H,13C and 15N,save speciﬁed.Chemical shifts (d in ppm)are given from internal solvents,DMSO-d 6(2.49)and CD 3CN (1.93)for 1H and DMSO-d 6(39.5)and CD 3CN (118.7)for 13C.And external reference CH 315NO 2(0.00)for 15N NMR was used.2D (1H–1H)gs-COSY and inverse protondetectedView along the b axis showing the zig-zag chain and the H-bonds compound 3.Table 1Halogen bond interactions (Åand °)for 1and 2and hydrogen bonds (Åand °)for pound Interactions Symmetry operations d (Br–O)1Br ÁÁÁO1x ,Ày +1/2,z À1/2 3.089(1)2Br ÁÁÁO1x À1,y ,z 2.357(1)2Br ÁÁÁO2x À1,y ,z2.194(1)D–H ÁÁÁAd (D–H)d (H ÁÁÁA)d (D ÁÁÁA)\(DHA)3N1–H1ÁÁÁO2 1.04 2.15 2.708(3)111.73N1–H1–N20x À1/2,Ày +1/2,Àz +1 1.042.213.019(3)133.8Table 213C and15N chemical shifts (d in ppm)and coupling constants (J in Hz).Nuclei1233DMSO-d 6DMSO-d 6CD 3CN THF-d 8300K300K 300K 207K C3121.1(d)111.0(m)151.5(m)150.83J =4.0C3a 127.3(d)124.9(d)120.2(d)119.72J =9.42J =9.22J =9.5C4127.2(dd)128.3(dd)130.3(dd)129.91J =167.01J =166.51J =171.73J =8.53J =8.13J =8.6C5121.2(d)120.8(d)126.4(d)125.81J =168.81J =167.41J =168.7C6126.0(ddd)125.9(ddd)126.8(ddd)126.01J =167.21J =167.41J =168.52J =2.9,3J =7.72J =2.9,3J =9.52J =2.3,3J =8.6C7135.0(d)136.4(d)134.9(m)134.83J =9.23J =7.7C7a 131.9(dd)139.3(dd)135.4(dd)135.13J =3J =6.93J =3J =6.93J =3J =6.7Me 40.9(q)39.5(q)––1J =142.51J =142.0N1À198.9À87.1À199.7a À200.0a N2À53.6À155.2À64.2aÀ63.3aNO 2À11.3aÀ11.3aÀ21.5a (NO 2-3)À24.6a (NO 2-3)À14.3a (NO 2-7)À17.1a (NO 2-7)aTo obtain these 15N NMR chemical shifts the use of a 5-mm inverse detection QNP probe equipped with a z -gradient coil,at 333K for 1and 2and 300K for 3,was necessary;d:doublet;m:multiplet;q:quartet.Structure 985(2011)75–81heteronuclear shift correlation spectra,(1H–13C)gs-HMQC, (1H–13C)gs-HMBC,(1H–15N)gs-HMQC,and(1H–15N)gs-HMBC, were acquired and processed using standard Bruker NMR software and in non-phase-sensitive mode[35].Gradient selection was achieved through a5%sine truncated shaped pulse gradient of 1ms.Variable temperature experiments were recorded on the same spectrometer.A Bruker BVT3000temperature unit was used to control the temperature of the cooling gas stream and an ex-changer to achieve low temperatures.Solid state13C(100.73MHz)and15N(40.60MHz)CPMAS NMR spectra have been obtained on a Bruker WB400spectrometer at 300K using a4mm DVT probehead and a4-mm diameter cylindri-cal zirconia rotor with Kel-F end-caps.The non-quaternary sup-pression(NQS)technique to observe only the quaternary carbonP.Cabildo et al./Journal of Molecular Structure985(2011)75–8179atoms was employed [35].13C spectra were originally referenced to a glycine sample and then the chemical shifts were recalculated to the Me 4Si (for the carbonyl atom d (glycine)=176.1ppm)and 15N spectra to 15NH 4Cl and then converted to nitromethane scale using the relationship:d 15N(nitromethane)=d 15N(ammonium chloride)–338.1ppm.4.3.X-ray data collection and structure reﬁnement for compounds 1,2and 3Suitable crystals for X-ray diffraction experiments were ob-tained by crystallization from acetone–water for 1,from ethyl ace-tate–hexane for 2and from tetrahydrofurane for 3.Data collection for all compounds was carried out at room temperature on a Bru-ker Smart CCD diffractometer using graphite-monochromated Mo K a radiation (k =0.71073Å)operating at 50kV and 30mA.In all cases,the data were collected over a hemisphere of the recipro-cal space by combination of three exposure sets.Each frame expo-sure time was 20s,covering 0.3°in x .The cell parameters were determined and reﬁned by least-squares ﬁt of all reﬂections col-lected.The ﬁrst 100frames were recollected at the end of the data collection to monitor crystal decay,and no appreciable decay was observed.An empirical absorption correction was applied for 1and 2compounds.A summary of the fundamental crystal and reﬁne-ment data is given in Table 4.The structures of all the compounds were solved by direct methods and reﬁned by full-matrix least-squares on F 2(SHELXL-97).All non-hydrogen atoms were reﬁned anisotropically.In all cases the hydrogen atoms were included withﬁxed isotropic contributions at their calculated positions deter-mined by molecular geometry except for the H1bonded to N1for 3,which was located from the Fourier map and included.All hydrogen reﬁned riding on the corresponding bonded atom.All the calculations were carried out with SHELX-97[36]putational detailsTheoretical calculations were carried out within the Gaussian 03facilities [37].The geometries were fully optimized at the B3LYP/6-311++G(d,p)level [38,39],and frequency calculations veriﬁed its minimum nature.On these geometries GIAO calculations [40]were carried out.Supplementary materialCrystallographic data for molecules 1,2and 3have been deposited at the Cambridge Crystallographic Data Center with the deposition numbers CCDC –780744,CCDC –780745and CCDC –780746.Copies of the data can be obtained free of charge via external link /retrieving.html .AcknowledgementsThis work has been ﬁnanced by the Spanish MICINN (CTQ2007-62113,CTQ2009-13129-C02-02and CTQ2010-16122)and Comun-idad Autónoma de Madrid (Project MADRISOLAR2,ref S2009/PPQ-1533).Table 313C and15N chemical shifts (d in ppm)in solid-state (CPMAS,300K).Comp.C3C3a C4C5C6C7C7a Me N1N2NO 21118.7126.0128.6118.7124.6132.2131.842.4À197.8À50.6À7.02121.5127.5127.5121.5127.5136.5138.040.5À87.1À153.5À8.43149.5117.5132.3126.3126.3132.3134.6–À197.0À71.3À12.0(NO 2-7)À20.5(NO 2-3)Table 4Crystal data and structure reﬁnement for compounds 1,2and 3.Crystal Data123Identiﬁcation code CCDC –780744CCDC –780745CCDC –780746Empirical formula C 8H 6BrN 3O 2C 8H 6BrN 3O 2C 7H 4N 4O 4Formula weight 256.07256.07208.14Wavelength (Å)0.710730.710730.71073Crystal system Orthorhombic Monoclinic Orthorhombic Space groupPbcaP2(1)/c P2(1)2(1)2(1)Unit cell dimensions a (Å)12.705(2)9.882(2) 4.9853(7)b (Å) 6.994(1)7.111(2)12.265(2)c (Å)20.436(3)13.357(3)13.265(2)b (°)–À106.255(4)–Volume (Å3)1808.0(5)901.0(3)811.1(2)Z844Density (calculated)(Mg/m 3) 1.8811.8881.713Absorption coefﬁcient 4.522(mm À1) 4.537(mm À1)0.144(mm À1)F (000)424504424Theta range (°)for data collection 2.23–25.0 2.29–25.0 2.26–25.00Index rangesÀ156h 613À116h 611À56h 65À86k 68À86k 68À146k 612À246l 624À146l 615À146l 615Reﬂections collected12,23763006204Independent reﬂec.[R (int)]1594[0.0532]1580[0.0448]1422[0.0654]Data/restraints/parameters 1594/0/1281580/0/1271422/0/137Goodness-of-ﬁt on F 21.0121.0060.833R a [I >2sigma(I )](obs.reﬂec.)0.0776(1185)0.0304(1070)0.0328(885)Rw F b (all data)0.21800.09210.0703a P||F o |À|F c ||/P |F o |.b{P [w (F 2o ÀF 2c )2]/P [w (F 2o Þ2]}1/2.80P.Cabildo et al./Journal of Molecular Structure 985(2011)75–81References[1]R.M.J.Palmer,A.G.Ferrige,S.Moncada,Nature327(1987)524.[2]C.López,R.M.Claramunt,S.Troﬁmenko,J.Elguero,Can.J.Chem.71(1993)678.[3]M.A.García,C.López,R.M.Claramunt,A.Kenz,M.Pierrot,J.Elguero,Helv.Chim.Acta85(2002)2763.[4]J.Teichert,P.Oulié,K.Jacob,L.Vendier,M.Etienne,R.M.Claramunt,C.López,C.Pérez Medina,I.Alkorta,J.Elguero,New J.Chem.31(2007)936.[5]C.Pérez Medina,C.López,R.M.Claramunt,J.Elguero,J.Heterocycl.Chem.46(2009)1408.[6]C.Pérez Medina,C.López,R.M.Claramunt,J.Elguero,.Chem.(2010)890.[7]R.M.Claramunt,C.López,C.Pérez-Medina,M.Pérez-Torralba,J.Elguero,G.Escames,D.Acuña-Castroviejo,Bioorg.Med.Chem.17(2009)6180.[8]J.Elguero,I.Alkorta,R.M.Claramunt,C.López,D.Sanz,D.Santa María,Bioorg.Med.Chem.17(2009)8027.[9]R.M.Claramunt,C.López,A.López,C.Pérez-Medina,M.Pérez-Torralba,I.Alkorta,J.Elguero,G.Escames, D.Acuña-Castroviejo,Eur.J.Med.Chem., submitted for publication.[10]K.von Auwers,W.Demuth,Ann.Chem.451(1927)295.[11]R.Sureau,Chimia15(1961)195.[12]M.Benchidmi,P.Bouchet,zaro,J.Heterocycl.Chem.16(1979)1599.[13]P.Bouchet,zaro,M.Benchidmi,J.Elguero,Tetrahedron36(1980)3523.[14]L.Bouissane,S.E.Kazzouli,J.M.Léger, C.Jarry, E.M.Rakib,M.Khouili,G.Guillaumet,Tetrahedron61(2005)8218.[15]B.Cottyn,F.Acher,B.Ramassamy,L.Alvey,M.Lepoivre,Y.Frapart,D.Stuehr,D.Mansuy,J.L.Boucher,D.Vichard,Bioorg.Med.Chem.16(2008)5962.[16]L.Habraken,P.Cohen-Fernandes,.Chem.36(1971)3084.[17]U.Wrzeciono,E.Linkowska,A.Rogowska,koma,D.Kubiak,Pharmazie39(1984)389.[18]arewicz,U.Wrzeciono,Z.Lukaszewski,R.Gatniejewska,K.Peisert,Pharmazie47(1992)15.[19]A.C.Legon,Phys.Chem.Chem.Phys.12(2010)7736.[20]P.Politzer,J.S.Murray,T.Clark,Phys.Chem.Chem.Phys.12(2010)7748.[21]Y.X.Lu,J.W.Zou,Y.H.Wang,Q.S.Yu,J.Mol.Struct.Theochem767(2006)139.[22]M.Kubicki,P.Wagner,Acta Crystallogr.Sect.C63(2007)o454.[23]Y.H.Wang,L.Li,Y.X.Lu,J.W.Zou,Chin.J.Chem.Phys.20(2007)531.[24]L.S.Szczepura,K.K.Eilts,A.K.Hermetet,L.J.Ackerman,J.K.Swearingen,D.X.West,J.Mol.Struct.607(2002)101.[25]B.Vickery,G.R.Willey,M.G.B.Drew,J.Chem.Soc.Perkin Trans.2(1981)155.[26]B.Vickery,G.R.Willey,M.G.B.Drew,Acta Crystallogr.Sect.C.41(1985)586.[27]I.G.Krivoruchka,A.I.Vokin,V.K.Turchaninov,.Chem.38(2002)1456.[28]J.Elguero,A.Fruchier,E.M.Tjiou,S.Troﬁmenko,pd.(Engl.Ed.)31(1995)1006.[29]R.M.Claramunt,D.Sanz,C.López,J.A.Jiménez,M.L.Jimeno,J.Elguero,A.Fruchier,Magn.Res.Chem.35(1997)35.[30]rina,V.Lopyrev,Nitroazoles:Synthesis,Structure and Applications,Springer,Berlin,2009.[31]I.Alkorta,J.Elguero,.Chem.18(2005)719.[32]F.Blanco,I.Alkorta,J.Elguero,Magn.Reson.Chem.45(2007)797.[33]A.M.S.Silva,R.M.S.Sousa,M.L.Jimeno,F.Blanco,I.Alkorta,J.Elguero,Magn.Reson.Chem.46(2008)859.[34]C.P.Frizzo,M.A.P.Martins,M.R.B.Marzari,P.T.Campos,R.M.Claramunt,M.A.García,D.Sanz,I.Alkorta,J.Elguero,J.Heterocycl.Chem.doi:10.1002/jhet.377.[35]S.Berger,S.Braun,200And More NMR Experiments,Wiley-VCH,Weinheim,2004.[36]G.M.Sheldrick,SHELX97,Program for Reﬁnement of Crystal Structure,University of Göttingen,Göttingen,Germany,1997.[37]M.J.Frisch,G.W.Trucks,H.B.Schlegel,G.E.Scuseria,M.A.Robb,J.R.Cheeseman,J.A.Montgomery Jr.,T.Vreven,K.N.Kudin,J.C.Burant,lam,S.S.Iyengar, J.Tomasi,V.Barone, B.Mennucci,M.Cossi,G.Scalmani,N.Rega,G.A.Petersson,H.Nakatsuji,M.Hada,M.Ehara,K.Toyota,R.Fukuda,J.Hasegawa, M.Ishida,T.Nakajima,Y.Honda,O.Kitao,H.Nakai,M.Klene,X.Li,J.E.Knox,H.P.Hratchian,J.B.Cross,C.Adamo,J.Jaramillo,R.Gomperts,R.E.Stratmann,O.Yazyev,A.J.Austin,R.Cammi,C.Pomelli,J.W.Ochterski,P.Y.Ayala,K.Morokuma,G.A.Voth,P.Salvador,J.J.Dannenberg,V.G.Zakrzewski,S.Dapprich,A.D.Daniels,M.C.Strain,O.Farkas,D.K.Malick,A.D.Rabuck,K.Raghavachari,J.B.Foresman,J.V.Ortiz,Q.Cui, A.G.Baboul,S.Clifford,J.Cioslowski,B.B.Stefanov,G.Liu,A.Liashenko,P.Piskorz,I.Komaromi,R.L.Martin, D.J.Fox,T.Keith,M.A.Al-Laham, C.Y.Peng, A.Nanayakkara,M.Challacombe,P.M.W.Gill,B.Johnson,W.Chen,M.W.Wong,C.Gonzalez,J.A.Pople,Gaussian03,Gaussian,Inc.,Pittsburgh PA,2003.[38]A.D.Becke,Phys.Rev.A38(1988)3098;A.D.Becke,J.Chem.Phys.98(1993)5648;C.Lee,W.Yang,R.G.Parr,Phys.Rev.B37(1988)785.[39]P.A.Hariharan,J.A.Pople,Theor.Chim.Acta28(1973)213.[40]R.Ditchﬁeld,Mol.Phys.27(1974)789;F.London,J.Phys.Rad.8(1937)397.P.Cabildo et al./Journal of Molecular Structure985(2011)75–8181。