Synthesis and Characterization of Transparent Luminescent ZnSMnPMMA Nanocomposites

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Synthesis and characterization of novel systems fo

申请人：Pascal Dumy,Marie-Christine Favrot,Didier Boturyn,Jean-Luc Coll 地址：Allevard FR,Corenc FR,Grenoble FR,Claix FR 国籍：FR,FR,FR,FR 代理机构：DLA Piper LLP (US) 更多信息请下载全文后查看
专利内容由知识产权出版社提供
专利名称：Synthesis and characterization of novel systems for guidance and vectorization of molecules of therapeutic interest towards target cells
发明人：Pascal Dumy,Marie-Christine Favrot,Didier Boturyn,Jean-Luc Coll
申请号：US10528320 申请日：20030919 公开号：US07531622B2 公开日：20090512
摘要：A method for preparing a grafted homodetic cyclopeptide forming a framework that defines a grafted upper face and grafted lower face, including synthesizing a linear peptide from modified or unmodified amino acids, some of which carry orthogonal protective groups; intramolecular cyclizing the resulting protetuting some or all of orthogonal protective groups with a protected precursor; and grafting at least one molecule of interest onto one and/or the other face of the framework via an oxime bond.

纳米二氧化硅的改性与应用及聚倍半硅氧烷结构和性能研究

复旦大学碾士学位论文１．４．６复合材料中纳米二氧化硅的形貌表征图１—１１和１－１２是纳米二氧化硅ＳＰｌ和Ａ２００分散在丙烯酸树脂中的透射电镜照片。

与纳米二氧化硅在醋酸丁酯中的分散性一样，用ＭＡＰＴＳ改性的二氧化硅相对未改性的二氧化硅来说，具有较好的分散性，这点对于ＳＰｌ来说尤为明显（见图１—１ｌａ和１．１ｌｂ）。

另外，通过原位聚合制备的纳米复合材料中，二氧化硅的分散性优于通过共混法制各的（见图１－ｌｌｂ和】．１ｌｃ），这是由于改性的二氧化硅中含有可与丙烯酸酯单体反应的基团，在原位聚合中，与丙烯酸酯链段有较强作用，有利其分散。

然而这些对于纳米二氧化硅Ａ２００来说都不是那么明显（见图１－１２），无论是否改性，无论使用原位或者共混得方法，对于Ａ２００在丙烯酸树脂中的分散性没有很大影响。

这可能是纳米二氧化硅Ａ２００相对ＳＰｌ而言，本身就具有较小的比表面积以及较低的羟基含量，使其在丙烯酸树脂中具有比较好的分散性，所以通过ＭＡＰＴＳ对其改性，欲使其更易分散并没有在Ａ２００中体现出来。

（ａ）复旦大学硕士学位论文（ｃ）图１－ｌｌ含有ＳＰｌ的复合涂层的ＴＥＭ照片（ａ）含有共混的未改性的二氧化硅（ｂ）含有共混的改性的二氧化硅（ｃ）含有原位生成改性的二氧化硅Ｆｉｇｕｒｅ１－１１ＴＥＭｐｉｃｔｕｒｅｓｏｆｃｏｍｐｏｓｉｔｅｓｃｏｎｔａｉｎｉｎｇＳＰＩｐｒｅｐａｒｅｄｂｙ【ａ）ｂｌｅｎｄｉｎｇｗｉｔｈｕｎｍｏｄｉｆｉｅｄｎａｎｏ－ｓｉｌｉｃａ，（ｂ）ｂｌｅｎｄｉｎｇｗｉｔｈｍｏｄｉｆｉｅｄｎａｎｏ·ｓｉｌｉｃａａｎｄ（ｃ）ｉｎ—ｓｉｔｕｍｅｔｈｏｄｗｉｔｈｍｏｄｉｆｉｅｄｎａｎｏ－ｓｉｌｉｃａ（ａ）（ｂ）复旦大学硕士学位论文（ｃ）图１－１２含有Ａ２００的复合涂层的ＴＥＭ照片（ａ）含有共混的未改性的二氧化硅（ｂ）含有共混的改性的二氧化硅（ｃ）古有原位生成改性的二氧化硅Ｆｉｇｕｒｅ１－１２ＴＥＭｐｉｃｔｕｒｅｓｏｆｃｏｍｐｏｓｉｔｅｓｃｏｎｔａｉｎｉｎｇＡ２００ｐｒｅｐａｒｅｄｂｙ（ａ）ｂｌｅｎｄｉｎｇｗｉｔｈｕｎｍｏｄｉｆｉｅｄｎａｎｏ－ｓｉｌｉｃａ，（ｂ）ｂｌｅｎｄｉｎｇｗｉｔｈｍｏｄｉｆｉｅｄｒｉａｎｏ－ｓｉｌｉｃａａｎｄ（ｃ）ｉｎ－ｓｉｔｕｍｅｔｈｏｄｗｉｔｈｍｏｄｉｆｉｅｄｎａｎｏ．ｓｉｌｉｃａ１．４．７改性对复合树脂Ｔｇ的影响图１．１３至图１．１５为纳米复合树脂的ＤＭＡ损耗曲线。

Synthesis and characterization of carbon-doped titania as an artificial solar light photocatalyst

Synthesis and characterization of carbon-doped titania as an artiﬁcial solar light sensitive photocatalystYuanzhi Lia,b,Doo-Sun Hwang a ,Nam Hee Lee a ,Sun-Jae Kima,*aSejong Advanced Institute of Nano Technologies,#98Gunja-Dong,Gwangjin-Gu,Sejong University,Seoul 143-747,KoreabDepartment of Chemistry,China Three Gorges University,8College road,Yichang,Hubei 4430002,PR ChinaReceived 1December 2004;in ﬁnal form 4January 2005AbstractThe carbon-doped titania with high surface area was prepared by temperature-programmed carbonization of K-contained ana-tase titania under a ﬂow of cyclohexane.This carbon-doped titania has much better photocatalytic activity for gas-phase photo-oxi-dation of benzene under irradiation of artiﬁcial solar light than pure titania.The visible light photocatalytic activity is ascribed to the presence of oxygen vacancy states because of the formation of Ti 3+species between the valence and the conduction bands in the TiO 2band structure.The co-existence of K and carbonaceous species together stabilize Ti 3+species and the oxygen vacancy state in the as-synthesized carbon-doped titania.Ó2005Elsevier B.V.All rights reserved.Titania is well known as a cheap,nontoxic,eﬃcient photocatalyst for the detoxication of air and water pol-lutants.However,it is activated only under UV light irradiation because of its large band gap (3.2eV).Be-cause only 3%of the solar spectrum has wavelengths shorter than 400nm,it is very important and challeng-ing to develop eﬃcient visible light sensitive photocata-lysts by the modiﬁcation of titania.Several attempts have been made to narrow the band gap energy by tran-sition metal doping [1–3],but these metal-doped photo-catalysts have been shown to suﬀer from thermal instability,and metal centers act as electron traps,which reduce the photocatalytic eﬃciency.Recently,the mod-iﬁcation of titania by nonmetals (e.g.S,N,C,B)receive much attention as the incorporation of these nonmetals into titania could eﬃciently extend photo-response from UV (ultra-violet)to visible regions [4–10].Here,we re-port a method of synthesizing carbon-doped titania with a high surface area.It was found that the as-synthesizedcarbon-doped titania showed much better photocata-lytic activity for photo-oxidation of benzene under irra-diation of artiﬁcial solar light than undoped titania.The as-synthesized carbon-doped titania was pre-pared by the following procedure.0.10mol TiCl 4(98%TiCl 4,Aldrich)were added slowly drop wise into 200ml portions of distilled water in an ice bath.The ob-tained transparent TiOCl 2aqueous solution was heated rapidly to 100°C,and then kept at this temperature for 10min for hydrolysis of TiOCl 2.The precipitates formed in the solution were ﬁltered,neutralized to pH 8.0by 0.1mol/l KOH aqueous solution,washed thor-oughly with distilled water,and then ﬁnally dried at 150°C in air for 24h.The carbon-doped titania was prepared by temperature-programmed carbonization (TPC)of anatase titania in a ﬂow of Ar saturated by cyclohexane at 20°C in a quartz tube reactor.The load-ing of titania was 2g,and the ﬂowing rate of Ar was 500ml (STP)/min.The sample was heated to the car-bonization temperatures between 450and 500°C at a rate of 0.5°C/min and kept at the temperature for 2h.After rapidly cooling to room temperature in a ﬂow of Ar,a grayish sample of titania was obtained.0009-2614/$-see front matter Ó2005Elsevier B.V.All rights reserved.doi:10.1016/j.cplett.2005.01.062*Corresponding author.Fax:+82234083664.E-mail address:sjkim1@sejong.ac.kr (S.-J.Kim)./locate/cplettChemical Physics Letters 404(2005)25–29The crystalline phase of samples was determined by XRD.Before TPC,the obtained titania prepared by hydrolysis of TiOCl2aqueous solution had pure anatase structure.The crystalline phase of anatase sample was almost unchanged even after TPC except for the forma-tion of a small amount of rutile phase inﬁnally obtained carbon-doped pared to pure titania pre-pared by same procedure but replacing cyclohexane sat-urated Ar by air,the carbon doped titania has lower rutile content,indicating that TPC inhibited the trans-formation of anatase to rutile phase.The average crystal size of as-synthesized carbon-doped titania is estimated by the Scherrer formula:L=0.89k/b cos h to be7.6nm. BET surface area measurement showed that the as-syn-thesized carbon-doped titania by TPC at475°C had as high as204m2/g speciﬁc surface area,which is impor-tant for improving photocatalytic activity.But the car-bon-doped titania prepared by reported carbon doping method usually had a lower speciﬁc surface area and larger crystal size[11,12].Fig.1gives the UV–Vis diﬀusive reﬂectance absorp-tion spectra of the pure titania and carbon-doped titania pared to that of the carbon-doped titania, the absorption edge near400nm of the pure titania has a red-shift of20nm,which might be contributed by the higher content of rutile in pure titania than in carbon-doped titania,as rutile has a narrower band gap (3.0eV)than anatase(3.2eV).The as-synthesized pure titania almost has no absorption above400nm.How-ever,the doping of carbon results in obvious absorption of titania up to700nm.This absorption feature suggests that these carbon-doped titania can be activated by visible light.The photocatalytic activity of as-synthesized titania samples for the gas-phase oxidation of benzene was tested on a home-made re-circulating gas-phase photo-reactor with a quartz window,which was connected to the ppbRAE meter(RAE system Inc.)to re-circulate a mixture of benzene and ambient air without additional drying and measure concentration of the volatile organic compounds(VOCs).Artiﬁcial solar light with full spec-trum(32W VITA LITE lamp)was used as irradiation source.First,0.7000g titania powder was put into the reactor,then a known amount of benzene was injected in the system under dark.After the adsorption of benzene on titania reached to adsorption equilibrium,artiﬁcial solar light was turn on.Fig.2shows the amounts of total volatile organic compounds(VOCs)with the artiﬁcial so-lar light irradiation time.Morawski and co-workers[13] prepared carbon-modiﬁed titania by heating at the high temperatures of titanium dioxide in an atmosphere of gaseous n-hexane.They found that carbon-modiﬁed titania had catalytic photoactivity slightly lower than that of TiO2without carbon deposition.In our experi-ment of preparing anatase TiO2by hydrolysis of TiOCl2 solution,the precipitate was neutralized to pH8.0by 0.1mol/l KOH aqueous solution.When we did not use KOH solution to neutralize the titania precipitate and just washed thoroughly the titania precipitate with dis-tilled water.Then,we use this titania without neutraliza-tion by KOH solution to prepare the carbon-doped titania by TPC.It was found that this carbon-doped titania has almost similar photocatalytic activity for the gas-phase photo-oxidation of benzene to the un-doped titania prepared by the same procedure but replacing cyclohexane saturated Ar by air.This result is similar to the result reported by Morawski et al.How-ever,the as-synthesized carbon-doped titania,which was prepared by TPC of anatase titania with neutralization by KOH solution,have much better photoactivity for the gas-phase photo-oxidation of benzene than the un-doped titania as well as Degussa P25titania,a bench-marking photocatalyst.This result shows that the neutralization of titania by KOH solution plays very important role in the photocatlytic activity of theﬁnally obtained carbon-doped titania,and doping a proper26Y.Li et al./Chemical Physics Letters404(2005)25–29amount of carbon into the KOH neutralized titania by our method leads to the obvious enhancement of its photoactivity.Our experiment shows that theﬁnal carbonization temperature has an important eﬀect on the photoactiv-ity,and the optimum carbonization temperature is be-tween475and500°C.The photocatalytic activity of the as-synthesized carbon-doped titania is unchanged after several successive cycles of photocatalytic tests un-der artiﬁcial light irradiation,indicating the stability of the catalysts after photolysis.Asahi et al.[5]made a theoretical calculation of the densities of states(DOSs)of the substitutional doping of C,N,F,P,or S for O in the anatase TiO2crystal by the full-potential linearized augmented plane wave in the framework of the local density approximation (LDA).They thought that the substitutional doping of N or S was the most eﬀective because its p states contrib-ute to the band gap narrowing by mixing with O2p states,but the states introduced by C and P are too deep in the gap to satisfy one of the requirements for visible light sensitive photocatalyst.However,previous works [11,12,14]and our experiment show that the carbon-doped titania has visible light photocatalytic activity. Therefore,we must try toﬁnd the reason why as-synthe-sized carbon-doped titania has visible light photocata-lytic activity.To investigate the carbon states in the photocatalyst, C1s core levels were measured by X-ray photoemission spectroscopy(XPS),as shown in Fig.3a.There are two XPS peaks at284.6,288.2eV for the as-synthesized carbon-doped titania,but it was conﬁrmed that there was only one peak at284.6eV for pure titania even though it is not shown here.Obviously the peak at 284.6eV arises from adventitious elemental carbon. Hashimoto and co-workers[11]prepared carbon-doped titania by oxidizing TiC,and observed C1s XPS peak with much lower binding energy(281.8eV).They as-signed this C1s XPS peak to Ti–C bond in carbon-doped anatase titania by substituting some of the lattice oxygen atom by carbon.Khan et al.[12]synthesized carbon-modiﬁed rutile titania by controlledﬂame pyrolysis of Ti metal,and thought that the carbon substituted for some of the lattice oxygen atoms.However,Sakthivel and Kisch[14]prepared carbon-modiﬁed titania by hydrolysis of titanium tetrachloride with tetrabutylam-monium hydroxide followed by calcinations at400°C, and observed the two kinds of carbonate species with binding energies of287.5and288.5eV.These resultssuggest that the preparation method plays an important role in determining the carbon oxidation state in car-bon-modiﬁed titania:both substitution of the lattice oxygen in the titania and the formation of carbonate species in titania lead to the narrowing of the band gap inﬁnal obtained carbon-doped titania.Our result is similar to that of Sakthivel and Kisch,but the carbon-doped titania prepared by our method only has one peak nearby at288.2eV,indicating the presence of only one kind of carbonate species.Therefore,our result does not contradict the theoretical expectation of Asahi et al.because the carbon exists in form of carbonate, not by substituting the oxygen of the anatase in the as-synthesized carbon-doped titania.The sensitivity ofY.Li et al./Chemical Physics Letters404(2005)25–2927the as-synthesized carbon-doped titania to visible light maybe arises from other reason.The surface carbon concentration in our sample was estimated by XPS to be7.3%.The XPS spectral of Ti2p region were also shown(Fig.3b).The XPS spectra of Ti2p3/2in the car-bon-doped titania can beﬁtted as one peak at457.8eV. Compared to the binding energy of Ti4+in pure anatase titania(458.6eV),there is a red-shift of0.8eV for the carbon-doped titania,which suggests that Ti3+species was formed in the carbon-doped titania[15].In our experiment of preparing anatase TiO2,the precipitate was neutralized to pH8.0by0.1mol/l KOH aqueous solution.K was also detected by XPS in theﬁnally ob-tained carbon-doped titania prepared from this KOH neutralized titania.The XPS spectral of K2p region were also shown(Fig.3c).The XPS spectra of K2p3/2in the carbon-doped titania can beﬁtted as one peak at 292.5eV,which could be assigned to K+.The surface K concentration in our sample was estimated by XPS to be13.3%.Fig.4shows EPR spectra of as-synthesized doped titania,recorded at77K and ambient temperature un-der dark.The XPS results show the presence of Ti3+ in the as-synthesized carbon-doped titania.It can be seen from Fig.4that Ti3+is also detected by EPR at low temperature(77K).Moreover,there are observed two kinds of Ti3+in the as-synthesized carbon-doped titania.The signal at g^=1.9709,g i=1.9482is assigned to surface Ti3+[16,17],and the signal at g=1.9190is as-signed to vacancy-stabilized Ti3+in the lattice sites or similar center in the subsurface layer of titania[18,19]. At ambient temperature,the Ti3+EPR signal disap-pears,but the strong symmetric signal at g=2.0055still exists,and no EPR signal was detected for pure anatase titania.Moreover,our experiment showed that the used carbon-doped titania still had a strong EPR signal at g=2.0055after experienced photocatalytic test.Serwicka[20]observed a broad signal assigned to Ti3+ ions at g=1.96and a sharp signal at g=2.003on the vacuum-reduced TiO2at673–773K.They attributed the latter signal to a bulk defect,probably an electron trapped on an oxygen vacancy.Nakamura et al.[21]re-ported that the symmetrical and sharp EPR signal at g=2.004detected on plasma-treated TiO2arose from the electron trapped on the oxygen vacancy.The pres-ence of Ti3+in the as-synthesized carbon-doped titania implies that there must be some change for oxygen spe-cies localized near Ti3+in the carbon-doped titania to satisfy the requirement of charge equilibrium,which is further conﬁrmed by the EPR proof of the existence of vacancy-stabilized Ti3+in the as-synthesized carbon doped bined with the reported assignment for the EPR signal,the signal at g=2.0055newly ob-served here for the as-synthesized carbon-doped titania can be assigned to the electron trapped on the oxygen vacancy.It was reported that reducing TiO2introduces localized oxygen vacancy states located at0.75–1.18eV below the conduction band edge of TiO2[22],which re-sults in sensitivity of the reduced TiO x photocatalyst to visible light.So,for titania containing localized oxygen vacancy,the band gap between valence band and local-ized oxygen vacancy state is 2.45–2.02eV.Our UV experiments showed that the carbon-doped titania has an obvious absorption up to700nm(mainly in the re-gion of450–610nm(2.74–2.02eV))as shown in Fig.1, which further conﬁrms that localized oxygen vacancy states actually exist in the as-synthesized carbon-doped titania and the existence of localized oxygen vacancy states results in the sensitivity of the as-synthesized car-bon-doped titania photocatalyst to visible light.Based on our results of UV,XPS and EPR,it is concluded that the presence of Ti3+species produced in the process of carbon doping of the K-contained titania leads to the formation of oxygen vacancy state(O t.Ti3+)in the as-synthesized carbon-doped titania between the valence and the conduction bands in the TiO2band structure, which results in the sensitivity of the as-synthesized car-bon-doped titania to visible light and its high photocat-alytic activity under irradiation of artiﬁcial solar light.It was proved by our photocatalytic experiment that the oxygen vacancy state in the as-synthesized carbon-doped titania had good stability because its photocata-lytic activity was unchanged after several successive cycles of photocatalytic test under artiﬁcial light irradiation.We think that the co-existence of K and carbonaceous species together stabilize Ti3+species and the oxygen vacancy state in the as-synthesized carbon-doped titania.In summary,the carbon-doped titania with high sur-face area and good crystallinity was prepared by temper-ature-programmed carbonization of nano anatase titania withﬁnal carbonization temperature of475°C under aﬂow of cyclohexane.This carbon-doped titania28Y.Li et al./Chemical Physics Letters404(2005)25–29showed an obvious absorption of titania up to700nm, and had much better photocatalytic activity for gas-phase photo-oxidation of benzene under irradiation of artiﬁcial solar light than pure titania.The visible light photocatalytic activity is ascribed to the presence of oxy-gen vacancy state because of the formation of Ti3+spe-cies in the as-synthesized carbon-doped titania between the valence and the conduction bands in the TiO2band structure,which results in sensitivity of the as-synthe-sized carbon-doped titania to the visible light. AcknowledgmentsThe authors are grateful to Basic Research Program of Korea Science and Engineering Foundation(Grant No.R01-2002-000-00338)forﬁnancial support. 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配合物-多酸催化剂的制备及性能研究

Synthesis and catalytic properties of polyoxometalates modified with coordiationcompoundsCandidate Li YongSupervisor As. Pro. Tao-Hai LiCollege College of ChemistryProgram Inorganic ChemistrySpecialization Novel Advanced MaterialsDegree MasterUniversity Xiangtan UniversityDate April. 2012湘潭大学学位论文原创性声明本人郑重声明：所呈交的论文是本人在导师的指导下独立进行研究所取得的研究成果。

除了文中特别加以标注引用的内容外，本论文不包含任何其他个人或集体已经发表或撰写的成果作品。

对本文的研究做出重要贡献的个人和集体，均已在文中以明确方式标明。

本人完全意识到本声明的法律后果由本人承担。

作者签名：日期：年月日学位论文版权使用授权书本学位论文作者完全了解学校有关保留、使用学位论文的规定，同意学校保留并向国家有关部门或机构送交论文的复印件和电子版，允许论文被查阅和借阅。

本人授权湘潭大学可以将本学位论文的全部或部分内容编入有关数据库进行检索，可以采用影印、缩印或扫描等复制手段保存和汇编本学位论文。

涉密论文按学校规定处理。

作者签名：日期：年月日导师签名：日期：年月日摘要金属有机配合物具有良好的配位能力，丰富多样的结构，一定的催化氧化性和分子识别能力，一直以来都是人们研究的热点。

多酸由于其强酸性、氧化还原性、结构多样化等优点，被广泛应用于功能材料和催化领域。

因此，配合物与多酸的结合具有重要的研究意义和广泛的应用前景。

本文以几种具有高催化活性的金属有机配合物与几种常见的杂多酸为反应物，利用简单的化学共沉淀法制备了七种新型的配合物-多酸化合物：[Ru(2,2′-bi py)3]3(PW12O40)2(1)，[Ru(2,2′-bipy)3]3(PMo12O40)2(2)，[Ru(2,2′-bipy)3]2(SiW12O40) (3)，(CuC12H30N6)3(PW12O40)2(4)，(CuC12H30N6)3(PMo12O40)2(5)，(CuC12H30N6)2(S iW12O40)2(6)，(NiC10H26N6)3(PW12O40)2(7)。

Chemicalphysicsletters

Synthesis and optical characterization of strong red light emitting KLaF 4:Eu 3+nanophosphorsSubrata Das a ,A.Amarnath Reddy a ,Shahzad Ahmad b ,R.Nagarajan b ,G.Vijaya Prakash a ,⇑a Nanophotonics Laboratory,Department of Physics,Indian Institute of Technology Delhi,New Delhi 110016,India bMaterials Chemistry Group,Department of Chemistry,University of Delhi,New Delhi 110007,Indiaa r t i c l e i n f o Article history:Received 20February 2011In ﬁnal form 6April 2011Available online 9April 2011a b s t r a c tMonophasic KLaF 4possessing cubic symmetry with varied Eu 3+concentrations were synthesized by wet-chemical reaction.The obtained nanophosphor exhibits nanocrystals of 5nm size and the dopant Eu 3+ions were successfully incorporated into the sites of La 3+ions of the host lattice.The dominant red color emission at 612nm from the hypersensitive (5D 0?7F 2)transition of Eu 3+indicates the inversion anti-symmetry crystal ﬁeld around Eu 3+ion,which is favorable to improve the red color purity.Furthermore,the emission life times are high enough and our results broadly suggest the potential application for white LEDs,mercury-free lamps and display panels.Ó2011Elsevier B.V.All rights reserved.1.IntroductionIn recent years,a great deal of research effort has been devoted to the synthesis of rare-earth (Re 3+)doped nanocrystalline phos-phors due to their novel capabilities resulted from the quantum conﬁnement effects and a high surface-to-volume ratio compared to their bulk counterparts [1–5].Of these,ﬂuoride nanophosphors such as YF 3[3],NaYF 4[4,6],GdF 3[7],LiF [8],and LaF 3[9]are of spe-cial interest due to their many interlinked facts that could inﬂu-ence the emissive nature of Re 3+ions.The special class of ﬂuorides,Re 3+doped ALnF 4(A =Alkali ion,Ln =rare earth ion)phosphors (for ex:Re 3+-doped NaYF 4)are attractive,since the host provides very low phonon frequencies,optical transparency over a wide wavelength range and site-selective doping capability [4–6].Therefore,wide range of applications such as in vivo imaging of tis-sues and cells,solid state light emitting applications,scintillators and Thermally Stimulated Luminescence (TSL)dosimetry,have been intensely been investigated [6–9].In general,the emission mechanism of rare-earth ion is critically dependent on the relative energy of the 4f emitting level,site occupation and guest–host interactions.So far in ALaF 4(A =Na,K)doped phosphor systems,NaLaF 4nanocrystallines,has been widely studies but relatively few studies were reported in KLaF 4nanophosphors [5,10].Unlike the other ﬂuorides,KLaF 4usually exists in two phases:metastable cubic phase (a -KLaF 4)and more stable hexagonal phase (b -KLaF 4),depending on the synthetic conditions [5].Trivalent europium (Eu 3+)ion is widely recognized as an activa-tor for red emission (around 612nm),which has been used in most commercial red phosphors.The intra-4f-shell down-conversion transitions (5D 0?7F j (j =1,2,3,4))of Eu 3+ions are strongly dependent on crystal structure of the host and sensitive to the local environment where the rare-earth has been situated [11,12].Among all,the red color transition (5D 0?7F 2)of Eu 3+is the most intense and hypersensitive transition therefore the transition prob-abilities are strongly inﬂuenced by host lattice,specially the cova-lent nature of host and site symmetry of the occupation [11,12].In this Letter,we report monophasic red emitting Eu 3+doped KLaF 4nanophosphor,which can be effectively excited by UV/blue/green lights and suitable for use in white LEDs.2.ExperimentalA standard one-step procedure discussed elsewhere was fol-lowed for the preparation of KLaF 4nanophosphor [5,13].Stoichi-ometric amounts of Potassium Fluoride (KF)and Lanthanum (III)Acetylacetonate (LaC 15H 21O 6Áx H 2O)and appropriate amount of Europium (III)Chloride (EuCl 3Á6H 2O)were individually dissolved in appropriate amounts of anhydrous methanol and added drop-wise (ca.15–20min)with constant ter,the suspension was digested for 1h after which the product was separated by using ordinary ﬁltration and dried at room-temperature.X-ray diffraction (XRD)data for all these samples was collected on PAN analytical XPERT-PRO diffractometer with CuK a 1source (k =1.5405Å).The steady-state and time-resolved emission mea-surements were carried using home built setups using 532nm diode laser as excitation source,wherein the emission light was dispersed into a monochromator (Acton SP2300)coupled to a photo multiplier tube (PMT)through appropriate lens system.For time-resolved measurements,mechanical chopper (12Hz),lock-in ampliﬁer,and digital storage oscilloscope were employed.0009-2614/$-see front matter Ó2011Elsevier B.V.All rights reserved.doi:10.1016/j.cplett.2011.04.029⇑Corresponding author.Fax:+91(0)1126581114.E-mail address:********************.ac.in (G.Vijaya Prakash).3.Results and discussions 3.1.XRD and TEM studiesThe X-ray diffraction patterns of x mol%(x =0,1,3,5)Eu 3+-doped KLaF 4phosphors are presented in Figure 1A and the all the obtained patterns are identiﬁed as cubic KLaF 4having space group Fm3m (JCPDS File No.75-2020)[14].It is known that KLaF 4exhibit two phases,namely,a -phase (cubic)and b -phase (hexago-nal)depending on the synthesis conditions [5].The a -phase KLaF 4is a metastable high-temperature phase and is isomorphic with that of CaF 2,wherein the K +and La 3+ions are randomly coordi-nated and each cation is coordinated by F Àion again [5].As seen from Figure 1A,upon Eu 3+ion doping,the diffraction peaks are slightly shifted to the higher side by about 1–2°angles.These shifts in the XRD peaks are attributed to the substitution of the larger io-nic radius La 3+ions (117pm)by comparatively smaller ionic radius Eu 3+ions (108pm)in host lattice [7,15].This is further indicatingbroad diffraction peaks indicating the decrease in crystal size and the average crystallite sizes estimated from the Scherrer analysis were in the range of 5–15nm.The TEM image (Figure 1B)of 5mol%Eu 3+-doped KLaF 4shows that the sample precipitates into agglomerated nanosized particles of average grain size 5nm,which is close to the particle size estimated from XRD data.3.2.Photoluminescence studiesThe room temperature PL spectra of x mol%(x =1,3,5,10)Eu 3+-doped KLaF 4nanophosphors under 532nm laser,is shown in the Figure 2A.The spectra consists of several emission peaks at 579,594,612,650and 701nm which are corresponds to Eu 3+ion tran-sitions,5D 0?7F J (J =0,1,2,3,4)respectively.Out of all,the hyper-sensitive electric dipole transition at 612nm (5D 0?7F 2of Eu 3+)was found to be intense,which is responsible for the bright or-ange-red luminescence and the corresponding intensities shows a systematic enhancement with the increase of Eu 3+-doping con-X-ray diffraction pattern of x mol%(x =0,1,3,5)Eu 3+-doped KLaF 4nanophosphor.The XRD patterns were of 5mol%Eu 3+-doped KLaF 4nanophosphor.emission spectra of (A)x mol%(x =1,3,5,10)Eu 3+doped in KLaF 4nanophosphor (k exe =532nm)and excitation wavelengths.(5D0?7F2)purity can be achieved by introducing high degree of disorder,either by particle size reduction or introducing metallic and nonmetallic elements,as reported by many authors[30–33]. The dominant red emission from5D0?7F2transition indicates the inversion anti symmetry crystalﬁeld around Eu3+ion in the present nanophosphor,which is favorable to improve the color purity of the red phosphor[16,17].Moreover,the XRD patterns show that Eu3+ions are successfully incorporated into the sites of La3+in KLaF4lattice,which is further supporting the emission characteristics.In general,the transition probability of the magnetic-dipole transition5D0?7F1is nearly independent on the host matrix and the electric-dipole allowed5D0?7F2transition is strongly inﬂuenced by the local structure and site asymmetry around Eu3+ ion[17,18].Therefore,the emission intensity ratio between red and orange(R/O)color transitions corresponding to5D0?7F2 57To further illustrate the emission characteristics and the excita-tion wavelength dependence,several excitation wavelengths of commercially available excitation sources are used(Figure2B). The emission results show no spectral shift under different excita-tions and gives stable color purity at red-end wavelengths,which is favorable for LED applications.However,the excitations less than 532nm,the R/O ratios are more than2and such values are compa-rable to those reported for oxide phosphors.The R/O ratios of sev-eral reported Eu3+doped oxide andﬂuoride based phosphors are also given for comparison in Table1.A simple schematic energy le-vel diagram illustrating the excitation and emission transitions of Eu3+ions is shown in Figure3A.The emission intensity decay proﬁles for the612nm(5D0?7F2 of Eu3+)emission of the KLaF4:Eu3+nanophosphors were recorded and the decay curvesﬁts into a single-exponential function I=I0 exp(Àt/s)(I0is the initial emission intensity at t=0)(see Figure 3B).The emission life time values(s)obtained from single expo-nentialﬁts are given in Table1.The reason for mono-exponential nature is due to homogeneous distribution of doping ions inside the host matrix without any cluster formation[20].The lifetime (s)values increases from2.90to6.90ms as the Eu3+-concentra-tions increases from1.0to10mol%.The observed life time values for the present nanophosphors are much higher than the other oxide phosphors and close to theﬂuoride phosphors(Table1). These life time values are also consistent with the analogous phos-phor NaYF4:Eu3+[23].While the relative intensities of5D0?7F2of Eu3+emission transition are strongly inﬂuenced by their hypersen-sitivity to local environment,the radiative life times are dependent on various factors such as,covenant nature,polarisability,struc-tural defects and lattice arrangement[20,30–32].Comparatively larger lifetimes in the present nanophosphors can possibly be attributed to more radiative relaxation caused by surface defects, which can eventually act as luminescent centers.When the surface area increases with decrease in particle size,there are more and more defects which may act as luminescent centers in the sample. Broadly,the emission red-color richness and the larger lifetimes are suitable for potential applications in displays and lights,where high life times are required[21].Table1The emission life times of612nm(5D0?7F2of Eu3+)and Red-to-Orange(5D0?7F2/5D0?7F1of Eu3+)(R/O)intensity ratios of various Eu3+-doped KLaF4nanophosphors(k exe=532nm).The R/O ratios and emission life times of severalreported Eu3+doped phosphors are also given for comparison.Phosphor Life time‘s’(ms)R/O ratio ReferenceKLaF4:1mol%Eu3+ 2.86 1.29Present workKLaF4:3mol%Eu3+ 4.30 1.33Present workKLaF4:5mol%Eu3+ 5.40 1.35Present workKLaF4:10mol%Eu3+ 6.90 1.38Present workGdF3:5mol%Eu3+ 4.80 1.31*[7]CaF2:1.5mol%Eu3+ 2.08 1.43*[22]NaYF4:10mol%Eu3+ 6.20 1.59*[23]LaVO4:20mol%Eu3+0.12 1.43*[24]CaSc2O4:6mol%Eu3+ 1.00 1.30*[25]CaSiO3:4mol%Eu3+ 3.30 1.65*[26]Y2SiO5:1wt%Eu3+ 2.10 2.71[27]InVO4:30mol%Eu3+0.83 2.33*[28]YVO4:2mol%Eu3+0.54 1.24*[29]YPO4:2mol%Eu3+ 2.89 1.99*[29]La2O3:Eu3+ 1.38 3.98[30]*Estimated R/O values from respective references.excitation and emission transition energy level diagram of Eu3+ion.(B)Representative emission decay curve for612nanophosphor(k exe=532nm).S.Das et al./Chemical Physics Letters508(2011)117–120119competitive with that of commercialﬂuoride phosphors such as GdF3:Eu3+and CaF2:Eu3+.The ability to excite KLaF4:Eu3+with many commercially available UV,violet and green excitation sources to generate an intense red emission(612nm)makes these phosphors a very promising material for white light LED and other display applications.AcknowledgementAuthors acknowledge theﬁnancial support from Department of Information Technology(DIT),Govt.of India,under Photonics Development Program(ref:12(1)/2008-PDD).References[1]S.Lu,J.Zhang,J.Zhang,H.Zhao,Y.Luo,X.Ren,Nanotechnology21(2010)365709.[2]Y.Li,J.Zhang,X.Zhang,Y.Luo,S.Lu,Z.Hao,X.Wang,J.Phys.Chem.C113(2009)17705.[3]D.Chen,Y.Wang,Y.Yu,P.Huang,Appl.Phys.Lett.91(2007)051920.[4]G.Wang,Q.Peng,J.Solid State.Chem.184(2011)59.[5]N.Tyagi,A.Amarnath Reddy,R.Nagarajan,Opt.Mater.33(2010)42.[6]G.S.Yi,H.C.Lu,S.Y.Zhao,Y.Ge,W.J.Yang,D.P.Chen,L.H.Guo,Nano Lett.4(2004)2191.[7]X.Zhang,T.Hayakawa,M.Nogami,Y.Ishikawa,J.Alloys Compd.509(2011)2076.[8]C.Adachi,M.A.Baldo,M.E.Thompson,S.R.Forrest,J.Appl.Phys.90(2001)5048.[9]S.N.Achary,A.K.Tyagi,T.K.Seshagiri,V.N.Natarajan,Mater.Sci.Eng.B129(2006)256.[10]Z.Wang,C.Liu,Y.Wang,Z.Li,J.Alloys Compd.509(2011)1964.[11]Y.Huang,L.Shi,E.S.Kim,H.J.Seo,J.Appl.Phys.105(2009)013512.[12]Q.Ma,Y.Zhou,A.Zhang,M.Lu,G.Zhou,C.Li,Solid State Sci.11(2009)1124.[13]G.W.Pope,J.F.Steinbach,W.F.Wagner,J.Inorg.Nucl.Chem.20(1961)304.[14]W.H.Zachariasen,Acta Crystallogr.2(1949)388.[15]A.Sarakovskis,J.Grube,A.Mishnev,M.Springis,Opt.Mater.31(2009)1517.[16]M.Zhong,G.Shan,Y.Li,G.Wang,Y.Liu,Mater.Chem.Phys.106(2007)305.[17]L.Zhou,J.Wei,J.Wu,F.Gong,L.Yi,J.Huang,J.Alloys Compd.476(2009)390.[18]B.V.Rao,K.Jang,H.S.Lee,S.S.Yi,J.H.Jeong,J.Alloys Compd.496(2010)251.[19]G.Vijaya Prakash,R.Jagannathan,Spectrochim.Acta A55(1999)1799.[20]N.S.Singh,R.S.Ningthoujam,M.N.Luwang,S.D.Singh,R.K.Vatsa,Chem.Phys.Lett.480(2009)237.[21]C.Qin,Y.Huang,G.Chen,L.Shi,X.Qiao,J.Gan,H.J.Seo,Mater.Lett.63(2009)1162.[22]L.Song,J.Gao,R.Song,J.Lumin.130(2010)1179.[23]G.Jia,P.A.Tanner,J.Alloys Compd.471(2009)557.[24]S.W.Park et al.,Phys.B405(2010)4040.[25]Z.Hao,J.Zhang,X.Zhang,X.Wang,Opt.Mater.33(2011)355.[26]H.Nagabhushana, B.M.Nagabhushana,M.Madesh Kumar,Chikkahanumantharayappa,K.V.R.Murthy, C.Shivakumara,R.P.S.Chakradhar, Spectrochim.Acta A78(2011)64.[27]N.Rakov,D.F.Amaral,R.B.Guimarães,G.S.Maciel,J.Appl.Phys.108(2010)073501.[28]Y.S.Chang,Z.R.Shi,Y.Y.Tsai,S.Wu,H.L.Chen,Opt.Mater.33(2011)375.[29]G.Pan et al.,J.Appl.Phys.104(2008)084910.[30]L.Yu,H.Song,Z.Liu,L.Yang,S.Lu,Phys.Chem.Chem.Phys.8(2008)303.[31]X.C.Jiang,C.H.Yan,L.D.Sun,Z.G.Wei,C.S.Liao,J.Solid State.Chem.175(2003)245.[32]L.Wang,Y.Wang,J.Mater.Sci.43(2008)2908.[33]H.Q.Liu,L.L.Wang,S.Q.Chen,B.Zou,J.Lumin.126(2007)459.120S.Das et al./Chemical Physics Letters508(2011)117–120。

基于壳聚糖的分子印迹聚合物的制备和应用

化工进展 2016年第35卷·846·of Mn，Fe，Co，Ni，Cu and Zn：relationship to the 3-methyl analogs[J].Inorg. Chim. Acta，2000，300-302：1082-1089.[36] GHASSEMZADEH M，FALLAHNEDJAD L，HERA VI M M，et al.Synthesis，characterization and crystal structure of new silver(I) andpalladium(Ⅱ) complexes containing 1,2,4-triazole moieties[J]. Polyhedron，2008，27（6）：1655-1664.[37] ROBIN J Blagg R J，L´Opez-G´Omez M G，CHARMANT J P H，et al. The oxidative conversion of the N,S-bridged complexes[{RhLL’(μ-X)}2] to [(RhLL’)3(μ-X)2]+ (X = mt or taz)：acomparison with the oxidation of N,N-bridged analogues[J]. Dalton.Trans.，2011，40（43）：11497-11510.[38] CASTIN E A，GARCI´A-SANTOS I，DEHNEN S，et al. Synthesis，characterization and DFT calculations of a novel hexanuclear silver(I)cluster-complex containing 4-ethyl-5-pyridin-2-yl-2,4-dihydro-[1,2,4]triazol-3-thione as a result from the cyclization of 2-pyridinformamideN-4-ethylthiosemicarbazone [J]. Polyhedron，2006. 25（18）：3653-3660.[39] BHARTI A，BHARTY M K，KASHY AP S，et al. Hg(Ⅱ) complexesof 4-phenyl-5-(3-pyridyl)-1,2,4-triazole-3-thione and 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione and a Ni(Ⅱ) complex of 5-(thiophen-2-yl)-1,3,4-oxadiazole -2-thione：synthesis and X-ray structural studies[J].Polyhedron，2013，50（1）：582-591.[40] YU H X，MA J F，XU G H，et al. Syntheses and crystal structures offour new organotin complexes with Schiff bases containing triazole[J].J. Organomet. Chem.，2006，691（16）：3531-3539.[41] PATIL S A，MANJUNATHA M，KULKARNI A D，et al. Synthesis，characterization，fluorescence and biological studies of Mn(Ⅱ)，Fe(Ⅲ)and Zn(Ⅱ) complexes of Schiff bases derived from Isatin and 3-substituted-4-amino-5-mercapto-1,2,4-triazoles[J]. Complex. Met.，2014，1：128-137.[42] CAMMI R，LANFRANCHI M，MARCHIO L，et al. Synthesis andmolecular structure of the dihydrobis (thioxotriazolinyl) boratocomplexes of zinc(Ⅱ)，bismuth(Ⅲ)，and nickel(Ⅱ). M…H-Binteraction studied by Ab initio calculations[J]. Inorg. Chem.，2003，42（5）：1769-1778.[43] CHU W J，YAO H C，MA H C，et al. Syntheses，structures，andcharacterizations of two coordination polymers assembled from zinc(Ⅱ) salts with 1,2-bis[3-(1,2,4-triazolyl)-4-amino-5-carboxylmethylthio]ethane[J]. J. Coord. Chem.，2010，63（21）：3734-3742.[44] CHU W J，YAO H C，FAN Y T，et al. Anion exchange inducedtunable catalysis properties of an uncommon butterfly-liketetranuclear copper(Ⅱ) cluster and magnetic characterization[J].Dalton. Trans.，2011，40（11）：2555-2561.[45] CHU W J，HE Y，ZHAO Q H，et al. Two 3D network complexes ofY(Ⅲ) and Ce(Ⅲ) with 2-fold interpenetration and reversibledesorption-adsorption behavior of lattice water[J]. Journal of SolidState Chemistry，2010，183（10）：2298-2304.[46] CHU W J，HOU X W，ZHAO Q H，et al. Four novel lanthanide(Ⅲ)coordination polymers with 3D network structures containing 2-foldinterpenetration[J]. Inorg. Chem. Commun.，2010，13（1）：22-25. [47] AIN Q，PANDEY S K，PANDEY O P，et al. Synthesis，spectroscopic，thermal and antimicrobial studies of neodymium(Ⅲ) and samarium(Ⅲ) complexes derived from tetradentate ligands containing N and Sdonor atoms[J]. Spectrochim. Acta，Part A，2015，140：27-34.[48] BAHEMMAT S，GHASSEMZADEH M，AFSHARPOUR M，et al.Synthesis，characterization and crystal structure of a Pd(Ⅱ) complexcontaining a new bis-1,2,4-triazole ligand：a new precursor for thepreparation of Pd(0) nanoparticles[J]. Polyhedron，2015，89：196-202. [49] ZHANG R F，WANG Q F，LI Q L，et al. Syntheses andcharacterization of triorganotin(IV) complexes of Schiff base derivefrom 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol and 5-amino-1,3,4-thiadiazole-2-thiol with p-phthalaldehyde[J]. Inorg. Chim. Acta，2009，362（8）：2762-2769.[50] BHAT K S，POOJARY B，PRASAD D J，et al. Synthesis andantitumor activity studies of some new fused 1,2,4-triazole derivativescarrying 2,4-dichloro-5-fluorophenyl moiety[J]. Eur. J. Med. Chem.，2009，44：5066-5070.2016年第35卷第3期CHEMICAL INDUSTRY AND ENGINEERING PROGRESS ·847·化工进展基于壳聚糖的分子印迹聚合物的制备和应用许龙1，黄运安1，朱秋劲1，2，叶春1（1贵州大学酿酒与食品工程学院，贵州贵阳550025；2贵州大学食品科学工程研究中心，贵州贵阳550025）摘要：壳聚糖具有良好的生物相容性和独特的分子结构，基于其制备的分子印迹聚合物因亲和性和选择性高、应用范围广等特点引起了广泛的关注。

论文英文写作

SCI论文类型
论著（original articles）
综述（review）
会议摘要（meeting abstract）评述类论文（comments）读者来信（letters）假说和观点类论文（hypothesis）病例报道（case report）
SCI论文写作原则
试比较一下题名： a) Study of the solubility of polymers (聚合物的溶解性研究) b) Study on the thermodynamic problem of polychlorotrifluoroethylene dissolution (聚氯三氟乙烯的溶解热力学问题)
③ 陈述句式题名
由完整的句子组成，往往具有判断式的语意，即：使用一般现在时在题名中提出结论，正文中却探讨性地论证。
④ 疑问句式题名
多用于评论性论文，使用探讨性的疑问句型显得比较生动，激发读者兴趣。
例：
Dynamic capabilities: what are they? (动态能力：它们是什么？)
SCI论文写作技巧
• 用词
熟悉、具体、简单、短句式
• 时态
过去时现在时或现在完成时
• 词性
代词： is, this, these, those, that, which 冠词：a, an, the 动词：词性变化-ing, ed, en, d, t
• 标点
句号. 逗号, 括号(插入/附加) 所有格’ 连字符省略号…… 冒号：引号
Isolation of antigens from monkeys using complementfixation techniques (猴子使用补体固定技术分离的抗原) • 介词问题 ① “of”,“ for” 和 “in” 的使用 of——所有关系， for——目的、用途例如： A design method of sliding mode robust controller with feed forward compensator is presented (提出了一种具有前馈补偿的滑模鲁棒控制器设计方法)

苯甲叉基丙二腈中间体合成黄酮类化合物及表征

第 20 卷第 1 期湖南理工学院学报（自然科学版）V ol.20 No.12007 年 3 月Jour n al of Hu n a n Ins titu te of Sc ien ce a nd Tech n o lo gy (N atu ral Sc ien ce s)Mar .2007苯甲叉基丙二腈中间体合成黄酮类化合物及表征杨涛，周从山，谢芳（湖南理工学院化学化工系，湖南岳阳 414000）摘要：本文采用苯甲叉基丙二腈作为中间体，与间苯二酚在无水 ZnCl 2 和 HCl 气体的催化作用下制得亚胺盐，再水解,脱羧,分离得到产物,通过液相色谱、紫外、红外等手段对中间产物和最终产物进行分析鉴定，确定最终产物是 7-羟基二氢黄酮。

关键词：苯甲叉基丙二腈；黄酮；间苯二酚；7-羟基二氢黄酮中图分类号：O623.76文献标识码：A文章编号：1672-5298(2007)01-0080-03Synthesis using Phenylmethylenepropanedinitriles as intermediate and characterization of flavonoids compoundY ANG Tao, ZHOU Cong-shan, XIE Fang(Department of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Y ueyang 414000, C hina)Abstract: Two imino-compounds were obtained by the catalysis of ZnCl 2 and HCl using benzylidenemalononitrile and resorcinol as intermediate, which were directly hydrolyzed and decarboxylated without apart. The product was abstracted. All the intermediate and final product were analyzed and characterized by liquid chromatography, ultraviolet Spectrophotometer, infrared Spectrophotometer, we make sure that the final product is 7-hydroxy-2,3-dihydro-2-flaconoid.Key words: benzylidenemalononitrile ； falconoid ；resorcinol ；7-hydroxy-2,3-dihydro-2-flaconoid黄酮类化合物是一类广泛存在于自然界的天然有机化合物。

211050379_质谱在金属有机框架材料结构与应用表征上的研究进展

第 29 卷第 1 期分析测试技术与仪器Volume 29 Number 1 2023年3月ANALYSIS AND TESTING TECHNOLOGY AND INSTRUMENTS Mar. 2023浙江省大型科研仪器开放共享平台—质谱专栏(83 ~ 92)质谱在金属有机框架材料结构与应用表征上的研究进展陈银娟1 ，丁传凡2 ，卢星宇1（1. 西湖大学分子科学公共实验平台，浙江省功能分子精准合成重点实验室，浙江杭州　310024；2. 宁波大学材料科学与化学工程学院，浙江省先进质谱技术与分子检测重点实验室，质谱技术与应用研究院，浙江宁波　315211）摘要：金属有机框架材料（metal organic frameworks, MOFs）是指由金属离子或金属团簇与有机配体形成的一类多孔材料，具有比表面积大、气孔率高和热稳定性能优良等特点，在能源、环境、生物医药等领域应用广泛. 质谱可有效测定各种金属元素的成分和含量，精准分析化合物的组成和结构，其灵敏度高、分析速度快，是表征MOFs 的有效技术之一. 在质谱技术中，样品的离子化是进行质谱分析检测的重要前提，因此从常见离子源的原理与特点出发，对采用质谱技术表征MOFs的常用离子源种类、样品要求及产生的离子类型进行总结，并进一步对质谱在MOFs定性、反应监测及应用分析等方面的研究进展进行综述.关键词：质谱；金属有机框架材料；电喷雾电离；大气压化学电离；基质辅助激光脱附电离中图分类号：O657.63 文献标志码：A 文章编号：1006-3757（2023）01-0083-10DOI：10.16495/j.1006-3757.2023.01.013Progress of Mass Spectrometry to Metal Organic FrameworksCharacterization on Structure and ApplicationsCHEN Yinjuan1， DING Chuanfan2， LU Xingyu1（1. Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Instrumentation and Service Center for Molecular Sciences, Westlake University, Hangzhou 310024, China；2. Institute of Mass Spectrometry Technology and Application, Zhejiang Provincial Key Laboratory of Advanced Mass Spectrometry Technology and Molecular Detection, School of Materials Science and Chemical Engineering,Ningbo University, Ningbo 315211, Zhejiang China）Abstract：Metal-organic frameworks (MOFs) are a class of porous materials formed with metal ions or oligonuclear metallic complexes and organic ligands. MOFs have a wide range of applications in energy, environment and biomedicine areas due to their high specific surface area, high porosity, excellent thermal stability, etc. Mass spectrometry (MS) can efficiently identify specific metal species and precisely characterize compound composition, and its high sensitivity and fast analysis speed make it one of the effective methods for characterizing MOFs. In mass spectrometry, ionization of MOFs is an important prerequisite for mass spectrometric analysis and detection. Starting from the principles and characteristics of common ion sources, ion source, sample requirement and types of ions generated for characterizing MOFs by MS are summarized. Furthermore, the associated qualitative analysis, reaction monitoring and applications research of MOFs by MS are reviewed.收稿日期：2023−01−31；　修订日期：2023−03−03.作者简介：陈银娟（1986−），女，博士，研究方向：色谱/质谱方法学研究，E-mail：.Key words：MS；MOFs；electrospray ionization；atmospheric pressure chemical ionization；matrix-assisted laser desorption/ionization金属有机框架材料（metal-oragnic frameworks, MOFs）是一类由金属离子或金属簇与有机配体形成的具有一维、二维或三维的配合物材料. MOFs 具有比表面积大、气孔率高和热稳定性能优良等特点，常用于催化、化学传感器、无机和有机成分的吸附，如有毒成分或离子吸附等，备受化学、环境和生物医药等领域科研人员的青睐[1-7]. 因MOFs的重要理论和应用价值，科学家们根据它的空间结构及化学组成的特点，发展了一系列用于表征其性质的方法，如X-射线衍射（X-ray diffraction, XRD）、核磁共振波谱（nuclear magnetic resonance spectroscopy, NMR）、X-射线光电子能谱（X-ray photoelectron spectroscopy, XPS）、X-射线吸收谱（X-ray absorption spectroscopy, XAS）、扫描电子显微镜（scanning elec-tron microscopy, SEM）、傅里叶变换红外光谱（four-ier transform infrared spectroscopy, FTIR）、透射电子显微镜（transmission electron microscopy, TEM）及质谱（mass spectrometry, MS）等用于此类化合物的结构定性与应用表征[8-14]. 近年来，由于质谱技术的飞速发展，它可以快速准确地分析气相、液相、固相样品中各种物质的种类（定性分析）及其含量（定量分析），质谱与色谱联用还能进行复杂混合物的高灵敏分析，尤其是高分辨质谱分析可有效进行元素分析，精准推断化合物组成，在MOFs表征上显示出特有的优势.由于质谱的检测对象是离子，离子源是质谱的关键部件之一，它是将分子或原子电离成离子，然后供后续质量分析器分析. 离子源不仅为质谱仪提供可分析的样品离子，而且其种类与质谱的应用密切相关. 目前常用的商业化离子源包括：电喷雾电离（electrospray ionization, ESI）[15-16]、大气压化学电离（atmospheric pressure chemical ionization, APCI）[17]、电子轰击电离（electron-impact ionization, EI）[18-19]、基质辅助激光脱附电离（matrix-assisted laser desorp-tion/ionization, MALDI）[20-21]及电感耦合等离子电离（inductively coupled plasma, ICP）[22]等.基于MOFs的研究热点和质谱的技术优势，本文从常见离子源的原理和特点出发，总结了质谱用于MOFs 分析时样品的要求及离子化特点，并基于此进一步介绍了质谱在MOFs分析及应用表征方面的研究进展.1　离子源概述自1886年气体放电离子源（gas discharge ionization）作为质谱仪的首个离子源出现至今，各种电离技术层出不穷[23-24]. 2004年，电喷雾脱附电离（desorption electrospray ionization, DESI）的发明更是推动直接质谱分析技术的发展和应用[25]. 张兴磊等[26]从离子化能量作用方式概述了直接质谱技术的发展，并对近年来出现的新型离子化技术和装置进行了系统总结. 离子源的种类与样品性质和质谱应用相关，表1列举了常见离子源电离的特点及应用领域.1.1　ESIESI是目前应用最广泛的离子源之一. 1984年，表 1 常见离子源电离特点及应用Table 1　Characteristics and applications of several common ion sources离子源分类离子类型应用领域文献火花离子源（spark source, SS）放电原子离子固体样品，痕量分析[27]辉光放电（glow discharge, GD）等离子体诱导原子离子痕量分析[28]诱导耦合等离子体（inductively coupled plasma,ICP）等离子体诱导原子离子同位素分析，痕量分析[22]电子轰击（electron-impact ionization, EI）电子诱导不稳定的分子离子小分子，GC-MS数据库比对[18]化学电离（chemical ionization, CI）电子诱导不稳定的分子离子GC-MS[29]大气压化学电离（atmospheric pressure chemical ionization, APCI）电子诱导稳定的分子离子小分子，非极性或弱极性，LC-MS[17]大气压光电离（atmospheric pressure photoionization, APPI）光稳定的分子离子LC-MS，极性化合物[30]84分析测试技术与仪器第 29 卷美国化学家John Fenn和日本科学家Yamashita将ESI用作质谱离子源产生样品离子，后来进一步改进用作液相色谱-质谱（LC-MS）仪的接口. ESI电离的基本过程如图1 [36-37]（a）所示：样品溶于极性可挥发性溶剂中，并以一定流速经过石英毛细管. 在毛细管尖端加高电压场，尖端会产生带电小液滴. 带电小液滴经氮气流扫吹及加热等辅助去溶剂化作用，产生化合物离子[15-16]. “残余电荷机理”（charge residue model）[38]及“离子蒸发机理”（ion evapora-tion model）[39]常用于解释ESI电离的过程，Keberle 等[40-42]认为ESI是一种在大气环境下发生的特殊的电化学过程.ESI的出现是质谱发展史上的一次重大飞跃.该离子源的特点包括：ESI在大气压条件下电离，是LC-MS的完美接口. 软电离，可以用于分析非共价复合物（non-covalent complexes）. 产生多电荷离子，应用到生物大分子领域. 也可以用于适合分析极性化合物[40]. 基于以上特点，ESI电离MOFs如产生加合分子离子峰（比如[M+H]+，[M+Na]+），样品应有一定极性，通常有机配体需具有质子化结合位点[11, 43].1.2　APCIAPCI是在大气压条件下电离气体样品的离子源，适合分析非极性和弱极性化合物，弥补了ESI 电离此类化合物的不足，是LC-MS和气相色谱-质谱（GC-MS）的常见接口. APCI离子源结构如图1（b）所示：在电晕针上加电流，电晕放电产生稳定的反应离子（例如N2+），流动相载带的样品溶液，在加热和高流速气流作用下发生气化，气体样品分子与反应离子发生离子-分子反应产生样品离子[44-45]. APCI电离的样品需加热气化，因此需要待测样品沸点较低，加热易气化且应具有较好的热稳定性. APCI一般分析的是分子量在1 000以内的小分子.1.3　MALDIMALDI是另一种常用的商业离子源，尤其适用于聚合物、蛋白质、核酸等大分子样品的质谱分析. MALDI电离可分为三步：先将样品和基质混合，滴加到金属样品板上结晶. 基质一般是能显著吸收紫外光或红外光的小分子，如2, 5-二羟基苯甲酸（DHB），α-氰基-4-羟基肉桂酸（CHCA）等[46]. 脉冲激光束照射样品板后，基质分子吸收激光能量发生电离，样品和基质分子从样品板上脱附出来. 脱附的气体成分含有基质离子、基质分子、样品分子等. 基质离子与脱附出来的样品分子相互作用，诱导样品电离[如图1（c）所示].MALDI对盐和缓冲液等具有较好的耐受性，常用于分析血清、组织等生物样品[47]，MALDI成像技术也得到广泛地应用和发展[48-49]. MALDI通常电离产生单电荷离子，也是一种软电离方式，多用于表征超分子、聚合物及生物大分子等样品的分子量.1.4　EIEI是GC-MS的常用离子源，同APCI类似适合于电离稳定性好、易气化的化合物. 如图1（d）所示：样品气化后从轴向引入离子源腔体内，径向上的加热灯丝产生高能电子束，与样品分子发生碰撞，诱导分子电离[18]. 为提高电子-分子的碰撞概率，电子束两端会加入磁场. 在电子轰击过程中，分子化学键易断裂产生碎片离子，所以EI源是典型的硬电离. 碎片离子能提供化合物的结构信息，且碎裂程度可以通过降低电子束的能量进行调节. 电子束的能量通常为70 eV，可产生丰富的碎片离子[50]. EI源得到的质谱图与质谱仪种类无关，重现性好，后续续表 1离子源分类离子类型应用领域文献场电离（field ionization, FI）强电场不稳定的分子离子分子化合物[31]电喷雾电离（electrospray ionization, ESI）喷雾稳定的分子离子软电离，极性化合物[15]电喷雾脱附电离（desorption electrosprayionization, DESI）喷雾稳定的分子离子直接电离[25]实时直接分析（direct analysis in real time, DART）放电稳定的分子离子直接电离[32]二次离子电离（secondary ionization mass spectrometry, SIMS）微粒诱导脱附稳定的分子离子半导体分析，表面分析，质谱成像分析[33]快原子轰击（fast atom bombardment, FAB）微粒诱导脱附稳定的分子离子软电离，大分子[34]基质辅助激光脱附电离（matrix-assisted laser desorption/ionization, MALDI）光子诱导脱附稳定的分子离子软电离，大分子[35]第 1 期陈银娟，等：质谱在金属有机框架材料结构与应用表征上的研究进展85依据化合物谱库实现样品定性分析.1.5　ICPICP产生的是原子离子，用于对化合物组成的元素进行定性定量分析. 如图2所示，ICP的基本过程如下：蠕动泵载带样品溶液经过雾化器（nebulizer）形成气溶胶并到达雾化室（spray chamber），后经载气（carrier gas）携带进入ICP炬管. ICP炬管通常是由三层同心圆的石英管组成，炬管顶端盘绕着与射频电源相连的感应线圈（RF load coil）. 载气、辅助气（auxiliary gas）和等离子气（plasma gas）通常均为氩气，分别从炬管的内层、中层和外层流入. 高压电火花产生的电子与外层氩气碰撞，诱导其电离产生等离子体. 等离子体在振荡磁场作用下与氩原子碰撞释放欧姆热，致使等离子火焰温度可高达10 000 K. 样品溶液在高温作用下，发生去溶剂化、原子化并电离成原子离子，用质谱检测产生的离子，即为电感耦合等离子体质谱（inductively coupled plasma mass spectrometry, ICP-MS）[51-52]. ICP也存在原子跃迁激发再回到基态的过程，该过程以光子形式进行能量释放，用光谱仪检测光信号，即为电感耦合等离子体原子发射光谱法（inductively coupled plasma optical emission spectroscopy, ICP-OES）. 与ICP-OES 相比，ICP-MS具有灵敏度高、多元素检测和高通量的特点，常用于MOFs材料中元素的精准定量.1.6　MOFs样品离子化质谱检测的是离子，因此用质谱分析MOFs，样品须先进行离子化. Vikse等[53]将ESI-MS表征均相催化剂的电离方式分为三类：inherently-charged system，adventitiously-charged system以及intention-ally-charged system. 第一类，化合物本身带电，可用ESI-MS直接分析. 第二类，化合物是中性分子，在ESI电离过程中丢失负离子（如I−, Cl−）或者结合氢质子/碱金属离子发生离子化. 第三类，通过在化合物上引入酸/碱基团诱导化合物发生电离，同时保持化合物的立体效应和电子效应. 尽管离子化方式很多，但由于各类化合物状态、性质等差异性，还没有通用的离子源可以有效电离所有样品. 因此，在用质谱表征MOFs时，应根据化合物的类型、性质及常见商业离子源的特征合理选择离子化方式. 此外，由于MOFs配体种类及金属中心多种价态的复杂性，在分析质谱结果时，除查找常见的加H+或者加Na+质谱峰外，还应考虑其他的离子类型. 表2列举了用ESI、APCI、MALDI及EI电离MOFs时的样品要求及可能产生的离子类型.2　MOFs材料的质谱表征质谱表征的是离子的质荷比（m/z），高分辨质谱和串级质谱分析（tandem mass spectrometric analysis）(a) (c)(b)(d)magnetmagnettrap electronbeamsampleinletvaporizerrepellerfilamentto analyzerionsgas flownebulizer gasLCeffluentheatervaporsolvent,samplechemicalionizationsolvent ionssample ionsMScorona discharge needlemake-up gastylor coneliquid flowlaser pulse50 μm crystal surfacehigh voltagenozzle图1　（a）ESI [36]、（b）APCI [37]、（c）MALDI [36]和（d）EI [36]电离示意图Fig. 1　Schematics of (a) ESI [36], (b) APCI [37], (c) MALDI [36] and (d) EI[36]86分析测试技术与仪器第 29 卷不仅可以确定样品化学组成，而且可以提供样品结构信息. ESI 和APCI 作为LC-MS 的常见接口，可有效监测溶液中MOFs 催化反应等过程. 近年来，在线质谱分析技术的发展，能实时检测反应中间体或产物，对设计高效的MOFs 基催化剂、研究化学反应机理等起到了巨大的推动作用.2.1　精准分子量定性分子量是化合物的基本属性，根据高分辨质谱精准质荷比和同位素峰型，能对MOFs 进行定性分析. 氨基硫脲衍生物相关的金属配合物具有抗菌、抗肿瘤等药理性质，Ülküseven 等[8]合成了以Ni 、Ru 为金属中心，氨基硫脲衍生物为配体的配合物，并用APCI-MS 、NMR 和XRD 等对合成产物进行了表征. Touj 等[9, 56]利用ESI-MS 等表征合成的铜基N -杂环卡宾催化剂，并用于催化合成1, 2, 3-三氮唑. Liu 等[43]采用ESI-MS 等方法表征合成出的一系列含疏水配体的Ru-bda （bda = 2, 2 ' -bipyridine-6, 6 ' -dicarboxylate ）类催化剂，以研究催化剂外层的疏水作用对水的催化氧化的影响. 使用ESI-MS 监测同类催化剂在加入硝酸铈铵（Ce IV）后，观测到催化剂金属中心从Ru II氧化到Ru III的中间体质谱峰，证明引入外层疏水基团是一种调节质子-耦合电子转移反应（proton-coupled electron transfer ）的有效策略[12].该课题组还用ESI-MS 成功捕捉到Ru-bda 在水氧化表 2 常见离子源电离MOFs 样品要求及产生的正离子类型Table 2　Requirements of MOFs analyzed with several commercial ion sources and the common produced positive ions 离子源MOFs 样品正离子类型ESI化合物本身带电或者有极性分子或者极性配体.H 2O ，ACN (ACN=CH 3CN)，CH 3OH 等ESI 常见溶剂.M +, M 2+ [53]（本身带电），[M]+ [12, 54]（丢失电子，氧化），[M+H]+ [12, 43, 55]，[M+A]+ (A=Na +, K +……)[43]，[M-X]+ [A=Cl −, I −, Br −, OTf −（trifluoromethanesulfonate)……] [9, 56-58]，[M+S+H]+ (S=solvent molecule) [12]，[M-L+H]+(L=Ligand)（丢失中性配体）……APCI 非极性或者弱极性. H 2O ，ACN ，CH 3OH 等常见溶剂. 沸点低，热稳定好.MALDI 样品可含盐，难溶于H 2O ，ACN ，CH 3OH 等常见溶剂. 尤其适合大分子；有合适基质.EI 沸点低，热稳定好.(a)(c)temperature (K) ±10%(b)ion detectorion opticsinterfaceskimmer cone sampler coneICP torchnebulizerspray chamberperistaltic pumpRF power supplymechanical pumpturbomolecularpumpturbomolecularpumpquartz torchRF load coilRF voltage induces rapid oscillation of Ar ions andelectronssample aerosl is carried throughthe centre of the plasmaauxiliary or coolant gas carrier gasplasma gassamplequadrupole mass filter6 0006 2006 5006 8008 00010 000图2　(a) ICP-MS 仪器结构、(b) ICP 电离和 (c) 温度分布示意图[51]Fig. 2　Schematic diagrams of (a) ICP-MS, (b) ICP ionization and (c) temperature distribution[51]第 1 期陈银娟，等：质谱在金属有机框架材料结构与应用表征上的研究进展87催化过程中Ru III的准七配位中间体（如图3所示）[11].2.2　中间体监测及反应机理分析化学反应中间体监测是分析反应机理的有效途径，溶液中的反应中间体因含量低、寿命短、副反应多以及体系复杂等原因，中间体监测更具挑战.质谱分析灵敏度高，尤其是ESI 和APCI 可以作为质谱与液相色谱联用的接口，能分析混合物，有效捕获中间体信息. Rh 2(MEPY)4 (MEPY=methyl pyroglutamate) 是一种用于立体选择性转化的高效催化剂，其合成过程中会产生十多种不同的Rh 配合物，体系十分复杂. Welch 等[59]利用HPLC-ESI-MS 在线检测Rh 2(MEPY)4催化剂合成的不同反应时间中间产物Rh 2(OAc)n (MEPY)m （OAc=CH 3OO)的动态变化（如图4所示），结果表明除目标催化剂(a)(b)699.080 3701.079 5702.078 9703.078 2704.078 9705.077 9705.077 6706.078 0707.078 9708.081 4699.079 8701.075 3702.077 4703.076 5704.077 1706.080 7707.078 8708.081 5m /z699700701702703704705706707708709710m /z699700701702703704705706707708709710704.070 1703.071 1705.072 9706.071 0707.073 7708.076 2698.072 5700.071 7701.071 0702.070 4m /zm /z696698700702704706708710704.071 0703.071 4705.073 8706.071 4707.074 5708.077 6698.072 5700.072 3701.071 4702.071 4696698700702704706708710图3　（a）C 30H 26N 4O 10Ru II催化剂加入Ce IV盐前的质谱图(上层[C 30H 26N 4O 10Ru II+H]+理论谱，下层实验谱)，（b ）加入Ce IV盐后的质谱图（上层[C 30H 26N 4O 10Ru III ]+理论谱，下层实验谱）[11]Fig. 3　(a) Mass spectra of C 30H 26N 4O 10Ru IIcatalyst without Ce IV(upper: theoretical MS of [C 30H 26N 4O 10Ru II+H]+, lower:experimental MS of catalyst) and (b) with Ce IV(upper: theoretical MS of [C 30H 26N 4O 10Ru III ]+, lower: experimental MS ofcatalyst with Ce IV )[11]Rh 2 (AC)4Rh 2 (OAc)4Rh 2 (MEPY)4before heatingheat applied 24681012t /mint /mint /mint /mint /min24681012246810122468101224681012Rx. turns purple t =1 hr t =2 hr t =3 hr t =4 hr M−O=428 amu Rh 2 (OAc)3 (MEPY)1M+H=526 amuRh 2 (OAc)2 (MEPY)2M+H=609 amuRh 2 (OAc)1 (MEPY)3M+H=692 amuRh 2 (MEPY)4M+H=775 amut =5 hrMonitoring formation of Rh 2 (MEPY)4 using LC-MS with flow injection analysis40 00020 00080 00060 00040 00020 000125 000100 00075 00050 00025 000200 000150 000100 00050 0001 500 0001 000 000500 000图4　LC-MS 检测Rh 2(MEPY)4形成中各物种变化[59]Fig. 4　Monitoring formation of Rh 2(MEPY)4 using LC-MS with flow injection analysis[59]88分析测试技术与仪器第 29 卷外，还产生二取代和三取代异构体产物. Han 等[10]利用ESI-MS 研究了铜基MOFs 的生长机理，检测到结合H 2O 、甲醇、N , N -二甲基甲酰胺（DMF ）溶剂分子的MOFs 质谱峰，推测溶剂分子参与MOFs 形成过程并影响产生的MOFs 连接体（linker ）的含量.Salmanion 等[60]采用ESI-MS 研究析氧反应中Ni-Fe 基MOFs 催化剂的变化，在KOH 溶液中，检测到单个连接体，脱羧连接体等质谱峰，并结合NMR 结果推测在KOH 条件下连接体不稳定，导致催化剂易发生降解.2.3　质谱表征MOFs 应用基于质谱灵敏度高、检测速度快的优势，质谱常用于MOFs 精准分子量定性. 近年来，新型的质谱检测技术、原位在线分析越来越多地用于MOFs 材料及其应用表征. Welch 等[59]研究Rh 2(MEPY)4催化剂合成的不同反应时间中间产物变化，并进一步利用HPLC-ICP-MS 对中间体进行了动力学分析.Zhang 等[61]研究分子催化水氧化的反应机理，利用原位电化学质谱，首次报道了[(L 2−)Co IIIOH]和[(L 2−)Co IIIOOH]两种配体-中心-氧化中间体（ligand-centered-oxidation intermediate ），并进一步设计18O 标记实验，试用串级质谱对反应中间体进行确认，为单点催化水氧化的亲核进攻机理提供了有力证据[如图5（a ）（b ）所示]. Ren 等[62]利用质子转移反应-飞行时间质谱（PRT-TOF-MS ）在线检测到电催化还原二氧化碳过程中C1-C4产物及中间体，发现甲醛和乙醛并不是反应生成甲醇和乙醇/乙烯的主要中间体，丙醛还原是正丙醇生成的主要途径[如图5（c ）（d ）所示].MOFs 除用作催化剂外，还用于化合物吸附和(a)(c)PB WOC Intermediates(b)(d)100E =1.2 VE =1.5 V500Micro-EC cell nanospary emitterCarbon UMEPiezoelectric pistolO H OH O−(2e +H )−(e +H )−(e +H )−H (L ) Co (L ) Co =O (L ) Co =(L ) Co =O′(L ) Co O H(L ) Co OO HWNAThis work2 mmMS inletOOO ON N NN Co GC-PTR-TOF-MS Operando PTR-TOF-MSAnode AEM GDEFlow cell Flow cell FlowmeterFlowmeterPTR-TOF-MSYellow and maroon paths do not open at the same timeGas flowGCN gasCO ga_CO gasR e l a t i v e a b u n d a n c e 100500R e l a t i v e a b u n d a n c e440445450455460465470440445450455m /zm /z460465470445 [L 2−) CO III −O]−445 [L 2−) CO III−O]−[(L 2−) CO III −O+H 2O]−463[(L 2−) CO III −O+H 2O]−463[(L 2−) CO III −OO]−4618×10−0.5−2.0E (V) versus Hg/Hg/HgO I n t e n s i t y /a .u .7×106×105×104×103×102×101×100I n t e n s i t y /a .u .7×1012×1010×108×106×104×102×100255006×105×104×103×102×101×100CH CH CHOCu-1 GDE, 3.5 mol/L KOHCH CH CH OH and C H CH CHOC H OH and C H CH CHOC H OH and C H CH CH CHOCH CH CH OH and C H 0400800t /s t /s1 200 1 60000200400600800 1 000 1 200t /s0200400600800 1 000 1 200t /s2004006008001 0001 200−100−200−300−400−500J /(m A c m )I n t e n s i t y /a .u .J/(mA cm )25500J/(mA cm )图5　原位 EC-MS 和PRT-TOF-MS 在线分析MOFs 催化反应的装置及检测结果（a ）原位电化学质谱装置示意图及提出的水氧化机理[61]，（b ）Co 氧化物及超氧化物中间体质谱图[61]，（c ）PTR-TOF-MS 与气相离线使用（黄色）和在线检测（褐色）仪器示意图[62]，（d ）PTR-TOF-MS 在线检测C2，C3产物结果[62]Fig. 5　Schematic and analysis results of in situ EC-MS setup [61]and PRI-TOF MS instrument[62](a) schematic illustration of in situ EC-MS setup and proposed mechanism of water oxidation, (b) mass spectra of cobalt-oxo and cobalt-peroxo intermediates, (c) operation schematic of PTR-TOF-MS when coupled to a gas chromatograph (yellow line) and when used for operando measurements (maroon line), (d) operando measurement of C2 and C3 products第 1 期陈银娟，等：质谱在金属有机框架材料结构与应用表征上的研究进展89固相微萃取等样品前处理过程，供后续质谱进行样品分析，在环境等领域广泛应用[63-65]. Suwannakot等[66]将耐水性好的MOFs 材料，如ZIF-8、UiO-66、MIL88-A 等设计成探针，用于环境水样品中全氟辛酸（perfluorooctanoic acid, PFOA ）的吸附和快速预浓缩，并用纳升ESI-MS 对PFOA 进行检测，实现PFOA 的快速检测（<5 min ）和高灵敏度定量（ng/L ）.Jia 等[67]在MOFs 外层进行疏水性微孔有机网络修饰，用于吸附环境水样、PM2.5和食物样品中的多环芳烃（PAHs ），并进一步用GC-MS/MS 分析了PAHs 的种类和含量. 在生物领域，孕酮在哺乳类动物怀孕和生长中起重要作用，常规GC-MS 和LC-MS 检测孕酮需要复杂的样品前处理过程，Li 等[68]利用氨基修饰的MOFs 材料对生物样品中的孕酮进行固相微萃取处理，并用DART-MS 进行快速定量.3　总结与展望作为一种高灵敏度、高分辨率的快速分析手段，质谱已广泛用于MOFs 材料精准分子量定性、中间体监测、反应机理分析及MOFs 材料多领域应用上. 在MOFs 材料电离方面，由于样品稳定性、溶解性、分子量及溶液基质等限制，仍有少量体系因不能电离无法用质谱分析. 在反应机理研究方面，离线分析已很难满足需求，联用设备、实时分析已成为新型利器，质谱用于MOFs 体系的深入研究任重道远.参考文献：Jiao L, Wang Y, Jiang H L, et al. Metal-organic frame-works as platforms for catalytic applications [J ]. Ad-vanced Materials (Deerfield Beach, Fla)，2018，30（37）：e1703663.［ 1 ］Yang S S, Shi M Y, Tao Z R, et al. 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SYNTHESIS AND CHARACTERIZATION OF POLYROTAXANES MADE FROM α-CDs THREADED ONTO TRIBLOCK COPOLYME

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调制协同法制备ZIF-67 纳米晶

1 实验部分
1．1 ZIF-67 纳米晶的合成称取 0.4152 g Co(CH3COO)2 溶于 15 ml 去离子水中形成 A 溶液,另称（量）1.3686 g
2-甲基咪唑和不同量三乙胺（TEA）溶于 15 ml 去离子水中形成 B 溶液。搅拌 30 min 后，将 A、B 溶液混合，室温下搅拌反应 10 min 后离心洗涤，置于 60 ℃烘箱中干燥 24 h。 1．2 ZIF-67 纳米晶的表征
对应于物理吸附水、TEA 和未反应物种的释放，500oC 后骨架开始分解，失重率为 32%。TGA 数据证明
ZIF-67 材料具有高的稳定性。
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参考文献：
[1] WANG B, CÔTÉ A P, FURUKAWA H, O’KEEFFE M, YAGHI O M. Colossal cages in zeolitic imidazolate frameworks as selective carbon dioxide reservoirs[J]. Nature, 2008, 453: 207-212.
Abstract: Uniform zeolitic imidazolate framework-67 nanocrystals (70-260nm) have been prepared on a large scale via low-cost coordination-modulation method by using of triethylamine. Fascinating crystals morphologies, including near-dodecahedron nanocrystals, globular nanocrystals and near-spherical nanocrystals were obtained by judicious manipulation of triethylamine. The as-synthesized products were characterized by powder X-ray powder diffraction (XRD), scanning electron microscopy (SEM), FT-IR spectra and TGA analysis, respectively. Moreover, the mechanism of triethylamine in decreasing nanoparticles size was investigated, disclosing that the alkaline property plays a critical role in tuning the size and morphologies of ZIF-67 naonocrystals.

Synthesis and Characterization of Alumina Nanoparticles

This article was downloaded by: [Cold and Arid Regions Environmental and Engineering Research Institute] On: 01 April 2014, At: 00:59Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UKMaterials and Manufacturing ProcessesPublication details, including instructions for authors and subscription information:/loi/lmmp20Synthesis and Characterization of AluminaNanoparticles by Igepal CO-520 Stabilized ReverseMicelle and Sol-Gel ProcessingJ. Chandradass a & Dong-Sik Bae aa School of Nano and Advanced Materials Enginneering , Changwon National University ,Gyeongnam, South KoreaPublished online: 21 Jun 2008.PLEASE SCROLL DOWN FOR ARTICLEMaterials and Manufacturing Processes ,23:494–498,2008Copyright ©Taylor &Francis Group,LLC ISSN:1042-6914print/1532-2475online DOI:10.1080/10426910802104211Synthesis and Characterization of Alumina Nanoparticles by IgepalCO-520Stabilized Reverse Micelle and Sol-Gel ProcessingJ.Chandradass and Dong-Sik BaeSchool of Nano and Advanced Materials Enginneering,Changwon National University,Gyeongnam,South KoreaNanosized alumina powders have been prepared via reverse micelle and sol-gel processing.By stepwise hydrolysis using aqueous ammonia as the precipitant,hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of microemulsion consisting of cyclohexane as the oil phase,poly(oxyethylene)nonylphenyl ether (Igepal CO-520)as the non-ionic surfactant,and an aqueous solution containing aluminium nitrate as the water phase.The synthesized and calcined powders were characterized by thermogravimetry-differential thermal analysis,transmission electron microscopy,and scanning electron microscopy.The XRD analysis showed that the complete transformation from -Al 2O 3nanocrystalline to -Al 2O 3was observed at 1100 C.The resulting alumina nanopowder exhibits particle agglomerates of 135–200nm in average diameter occur when they calcined at 1200 C.The average particle size was found to increase with increase in water to surfactant (R )molar ratio.Keywords Al 2O 3;Ceramics;Characterization methods;Crystallization;Differential thermal analysis;Microemulsion;Nanopowder;Scanning electron microscopy;Sol-gel processing;Thermogravimetric analysis;Transmission electron microscopy;X-ray diffraction.IntroductionIn recent years,there has been an increasing interest in the synthesis of nanocrystalline metal oxides [1–5].Such nanocrystals are important for a variety of applications including fabrication of metal-ceramic laminate composites and as a reinforcement phase in polymer and brittle matrix composites.Corundum ( -Al 2O 3 is one of the most important ceramics materials.Nanocrystalline -Al 2O 3powder has considerable potential for a wide range of applications including high strength materials,electronic ceramics,and catalyst [6,7].In particular high quality nanocrystals of corundum are used as electronic substrates,bearing in watches and other ﬁne precision equipment [8]. -Al 2O 3powders prepared by conventional methods require high temperatures 1300–1600 C for solid-state thermally driven decomposition of the hydrates of alumina [7].Various methods for synthesizing -Al 2O 3include mechanical milling [9],vapor phase reaction [10],precipitation [11],sol-gel [12],hydrothermal [13],and combustion methods [14].Mechanical synthesis of -Al 2O 3requires extensive mechanical ball milling and easily introduces impurities.Vapor reaction for preparing ﬁne -Al 2O 3powder from a gas phase precursor demands high temperature above 1200 C.The precipitation method suffers from its complexity and time consuming (long washing times and aging time).The direct formation of -Al 2O 3via the hydrothermal method needs high temperature and pressure.The combustion method has been used to yield -Al 2O 3powders,whereas the powder obtained from the process is usually hard aggregated but contains nanosized primary particles.The sol-gel method based on molecularReceived November 11,2007;Accepted March 20,2008Address correspondence to Dong-Sik Bae,School of Nano and Advanced Materials Enginneering,Changwon National University,Gyeongnam 641773,South Korea;Fax:+82-55-262-6486;E-mail:dsbae7@changwon.ac.krprecursors usually makes use of metal alkoxides as raw materials.However,the high prices of alkoxides and long gelation periods limit the application of this method.Among all the chemical processes that were developed for the preparation of ﬁne ceramic powder a wide array of metal and metal oxide compounds [15–17],the microemulsion process involving reverse micelles has been demonstrated as a superior method [18]in terms of being able to deliver homogeneous and nanosized grains of a variety of oxides.A microemulsion system consists of an oil phase,a surfactant,and an aqueous phase.It is thermodynamically stable isotropic dispersion of the aqueous phase in the continuous oil phase [19].The size of the aqueous droplets is in the range of 5–10nm,rendering the microemulsion systems optically transparent.Chemical reactions,such as precipitation,will take place when droplets containing the desirable reactants collide with each other.The group of these aqueous droplets involving the microemulsion system will thus be acting as a nanosized reactor yielding nanosized particles.Recently,reverse micelle and sol-gel processing [20–22]have successfully prepared several important nanosized ceramic powder systems.Many of the processing parameters such as the concentration of inorganic salts in the aqueous phase and water to surfactant ratio R in the microemulsion,affect the characteristics including the particle size,particle size distribution,agglomerate size,and phases of the resulting ceramic powders.The objective of the present study is to investigate the feasibility of preparing ultraﬁne alumina nanoparticles by combining reverse micelle and sol-gel processing and to study the effect of water to surfactant ratio R .Experimental procedureTypically,microemulsions of total volume 20mL were prepared at ambient temperature in a 30mL vial with rapid stirring:these consisted of 4mL of nonionic surfactant poly(oxyethylene)nonylphenyl ether (Igepal CO-520,Aldrich Chemical Co.,USA),10ml of cyclohexane,494D o w n l o a d e d b y [C o l d a n d A r i d R e g i o n sE n v i r o n m e n t a l a n d E n g i n e e r i n g R e s e a r c h I n s t i t u t e ] a t 00:59 01 A p r i l 2014SYNTHESIS AND CHARACTERIZATION OF ALUMINA NANOPARTICLES 4950.65–1.32mL of 5×10−1M Al(NO 3 2·9H 2O solution (Aldrich Chemical Co.,USA)and deionized water.The size of the resulting particles was controlled by the ratio R =[water]/[surfactant].The microemulsion was mixed rapidly,and after 5minutes of equilibration,one drop (∼0.05ml)of hydrazine hydrate (9M N 2H 4·xH 2O,Aldrich Chemical Co.,USA)was added as a reducing agent.After nanosized water droplets were formed while stirring,NH 4OH (28%)(Dae Jung chemicals,Korea)was injected into the microemulsion.The microemulsion was then centrifuged to extract the particles,which were subsequently washed by ethanol to remove any residual surfactant.The thermal characteristics of alumina precursors were determined by thermogravimetry and differential thermal analysis (TA 5000/SDT 2960DSC Q10).The phase identiﬁcation of calcined powders was recorded by X-ray diffractometer (Philips X’pert MPD 3040).The size and morphology of the resulting powders were examined by transmission electron microscopy (TEM)and Scanning electron microscopy (SEM).Results and discussionTernary systems of cyclohexane/Igepal CO 520/water offer certain advantages:they are spheroidal and monodisperse aggregates where water is readily solublized in the polar core,forming a “water pool”characterized by the molar ratio of water to surfactant concentration R .Another important property of reverse micelle is their dynamic character;the “water pool”can exchange their contents by collision process.The aggregation and self-assembly of the alumina/surfactant/water species is complex and very little is known about the cluster growth and ﬁnal nanostructure as a function of synthesis condition.The molar ratio of water to surfactant can determine the size of the micro-emulsion water core [23].Therefore,the R -value can control the diameter of the nanoparticle in the micro-emulsion.The average size of the cluster was found to depend on the micelle size,the nature of the solvent,and the concentration of reagent.During the preparation of alumina nanoparticles,the following reaction might occur.Thermal behavior of the precursor determined by TG-DTA in oxygen up to 1200 C at a heating rate of 10 C/min is shown in Figs.1and 2,respectively.NH 3·H 2O →NH +4+OH (1)OH +Al +3→Al OH 3(2)Al OH 3→Al 2O 3+H 2O(3)In the temperature region between RT-180 C,a broad endothermic peak with a weight loss of 9%is attributed to the adsorption of physisorbed water.In the temperature region between 180–600 C,three exothermic peaks were observed at 208,288,and 390 C with a weight loss of 50%corresponding to the decomposition of organic residuals from the precursor.From the TGA curve it is also observed that the precursor exhibit weight loss at <600 C,and at >600 C the weightbecomesFigure 1.—DTA curve of alumina precursor ramped at 10 C/min in air.almost constant.The peak around 1200 C is attributed totransformation of -Al 2O 3from -Al 2O 3.X-ray diffraction (XRD)analysis of precursor powder calcined at 1000,1100,and 1200 C are shown in Fig.3.Diffraction peaks corresponding to -Al 2O 3and weak peaks of -Al 2O 3have been found for samples calcined at 1000 C for 2h indicating - -Al 2O 3transformation.The difference in the crystallization temperature of -Al 2O 3as observed in DTA and XRD could be because of the difference in heating schedule for the two samples.While XRD pattern was recorded on samples which were held for 2h at 1000 C,the DTA was done without any isothermal hold.Thus the isothermal hold at 1000 C has accelerated the transformation to -Al 2O 3at lower temperature.With the increase of calcinations,temperature to 1100 C -Al 2O 3disappears;only -Al 2O 3with low intensity peaks is found indicating complete transformation to -Al 2O 3.A typical XRD pattern of the resultant -Al 2O 3powders after calcinations at 1200 C (2h)are shown in Fig. 4.The crystalline size of the calcined powders (1200 C)atFigure 2.—TGA curve of alumina precursor ramped at 10 C/min in air.D o w n l o a d e d b y [C o l d a n d A r i d R e g i o n sE n v i r o n m e n t a l a n d E n g i n e e r i n g R e s e a r c h I n s t i t u t e ] a t 00:59 01 A p r i l 2014496J.CHANDRADASS AND D.-S.BAEFigure 3.—XRD patterns of the alumina nanoparticles synthesized at R =4and calcined at different temperatures (a)1000 C;(b)1100 C;(c)1200 C (•- -Al 2O 3; - -Al 2O 3 .different value of R has been obtained from X-ray line broadening studies using the Scherer equation [24].Table 1shows that water/surfactant molar ratio R inﬂuenced crystallite size.The crystallite size of the alumina nanoparticles increased with increase in R -value from 4to 8.An increase in the domain size of aqueous droplets,duetoFigure 4.—XRD patterns of the as-synthesized alumina nanoparticles calcined at 1200 C and as a function of R (a)R =4;(b)R =6;(c)R =8.Table 1.—The crystallite size of -Al 2O 3at 1200 C.R =[water]/[surfactant]Crystallite size (nm)481684896Figure 5.—TEM micrographs of as-synthesized alumina nanoparticles calcined at 1200 C and as a function of R (a)R =4;(b)R =6;(c)R =8.D o w n l o a d e d b y [C o l d a n d A r i d R e g i o n sE n v i r o n m e n t a l a n d E n g i n e e r i n g R e s e a r c h I n s t i t u t e ] a t 00:59 01 A p r i l 2014SYNTHESIS AND CHARACTERIZATION OF ALUMINA NANOPARTICLES497Figure 6.—SEM micrographs of as-synthesized alumina nanoparticles calcined at 1200 C and as a function of R (a)R =4;(b)R =6;(c)R =8.an increase in aqueous content in the microemulsion,will lead to an apparent increase in the size of the particle [19].The nucleation and growth of the alumina nanoparticles is likely to be a diffusion-controlled process through interaction between micelles,but it can be inﬂuenced by many other factors such as phase behavior and solubility,average occupancy of reacting species in the aqueous pool and the dynamic behavior of the microemulsion [25].The degree of agglomeration is evident in the TEM micrograph (Fig.5)showing average particle size increase from 135to 200nm as the R -value increases from 4to 8.This is also in agreement with the particle size range as observed from SEM (Fig.6).TEM micrographs (Fig.5)also show the alumina solid bridging (necking)links powder particles together between neighbouring particles.The particle size as observed from TEM is larger than that calculated from the Scherer formula.This is because the nanosized precursor particles derived from micro-emulsions have very high surface areas;thus they tend to aggregate together to form particle agglomerates in the calcined ceramic powders [26].ConclusionNanosized -Al 2O 3powders have been prepared via reverse micelle and sol-gel processing.The XRD analysis showed that the complete transformation from -Al 2O 3to -Al 2O 3was observed at 1100 C.The resulting alumina nanopowder exhibits particle agglomerates of 135–200nm in average diameter occur when they calcined at 1200 C.The average particle size was found to increase with increase in water to surfactant R molar 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routeusing inorganic salt for synthesizing Al 2O 3nanopowders.Nanostructured Materials 1998,10,543–550.13.Faneli,A.J.;Burlew,J.V.Preparation of ﬁne alumina powderin alcohol.Journal of American Ceramic Society 1986,69,C174–C175.14.Bhaduri,S.;Zhou,E.;Bhaduri,S.B.Auto ignition processingof nanocrystalline -Al 2O 3.Nanostructured Materials 1997,13,605–610.15.Sugimoto,T.;Kimijima,K.New approach to the formationmechanism of AgCl nanoparticle in a reverse miscelle system.Journal of Physical Chemistry B 2003,107,10753–10759.16.McLeod,M.C.;McHenry,R.S.;Beckman,E.J.;Roberts,C.B.Synthesis and stabilization of silver metallic nanoparticles and premetallic intermediates in perﬂuoropolyether/CO 2reverse micelle system.Journal of Physical Chemistry B 2003,107,2693–2700.17.Sun,W.;Xu,L.;Chu,Y.;Shi,W.Controllable synthesis andCatalytic properties of WO 3/ZrO 2mixed oxide nanoparticles.Journal of Colloid and Interface Science 2003,266,99–106.18.Boutonnet,M.;Kizling,J.;Stenius,P.;Maire,G.The preparationof monodisperse colloidal metal particles from microemulsion.Colloids Surfaces 1982,5,209–225.19.Fang,J.;Wang,J.;Ng,S.-C.;Chew, C.-H.;Gan,L.M.Ultraﬁne zirconia powders via microemulsion processing route.Nanostructured Materials 1997,8,499–505.20.Bae,D.S.;Kim,B.K.;Han,K.S.Fabrication and microstructureof ZnO-TiO 2composite membrane by a reverse micelle and sol-gel processing.Materials Science Forum 2006,510–511,786–789.21.Bae,D.S.;Han,K.S.;Adair,J.H.Synthesis of platinum/silicananocomposite particle by reverse micelle and sol-gel processing.Journal of American Ceramic Society 2002,85,1321–1323.22.Son,J.H.;Park,H.Y.;Kang, D.P.;Bae, D.S.Synthesis andcharacterization of Ag/Pd doped SiO 2nanoparticles by a reverse micelle and sol-gel processing.Colloids and Surfaces A:Physicochemical and Engineering Aspects 2008,313–314,105–107.23.Monnoyer,Ph.;Fonseca,A.;Nagy,J.B.Preparation of colloidalAgBr particles from microemulsions.Colloids and Surfaces A:Physicochemical and Engineering Aspects 1995,100,233–243.24.Klug,M.P.;Alexander,L.E.X-ray Diffraction Procedure forPolycrystalline and Amorphous Materials ;Wiley:New York,1974;634pp.25.Osseo-Asare,K.Handbook of Microemulsion Science andTechnology ;Marcel Dekker,Inc.,Basel:New York,1999;549pp.26.Chow,G.M.;Markowitz,M.A.;Rayne,R.;Dunn,D.N.;Singh,A.Phospholipid mediated synthesis and characterization of gold nanoparticles.Journal of Colloidal Interface Science 1996,183,135–142.D o w n l o a d e d b y [C o l d a n d A r i d R e g i o n sE n v i r o n m e n t a l a n d E n g i n e e r i n g R e s e a r c h I n s t i t u t e ] a t 00:59 01 A p r i l 2014。

Synthesis and characterization of ATO SiO2 nanocomposite coating obtained by sol–gel method

Synthesis and characterization of ATO/SiO 2nanocompositecoating obtained by sol–gel methodXiaoChuan Chen *The Key Laboratory of Materials Physics,Institute of Solid State Physics,Chinese Academy of Sciences,Hefei 230031,People’s Republic of ChinaReceived 19June 2004;accepted 20December 2004Available online 11January 2005AbstractA new sol–gel route was developed for synthesizing homogeneous nanocomposite thin film that was composed of Sb-SnO 2(ATO)nanoparticles and silica matrix.TEM studies show that as-prepared composite thin film contains the amorphous silica matrix and ATO nanocrystalline particles that were dispersed homogeneously in silica matrix.The oxalic acid is an excellent dispersant for colloidal stability of ATO aqueous sol at pH b 5.The result of Zeta potential measurement shows that dispersion mechanism comes from the chemisorption of oxalic acid on the surface of ATO nanoparticles.The thermal treatment in reducing atmosphere considerably promotes grain growth of ATO nanoparticles and changes the optical property of ATO/SiO 2nanocomposite thin film.D 2005Elsevier B.V .All rights reserved.Keywords:Sol–gel preparation;Thin films;Nanocomposites;Sb-doped SnO 21.IntroductionTin oxide is a wide band gap nonstoichiometric semi-conductor with a low n-type resistivity [1–3].The resistance can be reduced further by doping Sb,F elements [4,5].F-doped SnO 2(FTO),Sb-doped SnO 2(ATO)conducting thin films not only have high transparency in the visible region but also are good infrared reflecting materials [6,7].ATO thin films have been used in many fields such as heat shielding coating on low-emissivity window for energy saving [8].Fabrication techniques used to deposit ATO thin film include dip coating based on sol–gel method;sputtering and spray pyrolysis.The sol–gel route has several advantages over the other method.It is a low cost and simple process and makes the precise control of doping concentration easier [9,10].In order to improve the scratching abrasive resistance of ATO thin film prepared by sol–gel route [11,12]a novel sol–gel route has been proposed.In this technological process an organic–inorganic hybrid silica sol was used as the pre-cursor of protecting matrix.The ATO functional componentwas homogeneously distributed in a transparent silica matrix.The mixed structure is of benefit to preventing the crack of thin film in drying and annealing process [13].When a composite material containing two oxides with different pho-to index hopes to keep high transmittance in visible light re-gion the second phase component must be dispersed homogeneously into the amorphous matrix at a level of nanometer.In this work a transparent nanocomposite thin film com-posed of ATO and silica was synthesized by the sol–gel route.The sol–gel method includes (a)the synthesis of ATO sol and hybrid organic–inorganic silica sol;(b)mixing of two nanoparticulate sols.A TEM investigation of phase structure in ATO–silica composite gel is reported.The optical proper-ties and crystallizability of composite thin film is discussed.2.Experimental2.1.Preparation of ATO aqueous solAll the chemical reagents used in the synthesis experi-ment were obtained from commercial sources without0167-577X/$-see front matter D 2005Elsevier B.V .All rights reserved.doi:10.1016/j.matlet.2004.12.033*Tel.:+865515591477;fax:+865515591434.E-mail address:chenxiaochuan126@.Materials Letters 59(2005)1239–1242/locate/matletfurther purification.The aqueous ATO sol were prepared by a co-precipitation process from hydrolysis of SnCl4d5H2O and SbCl3,and followed by the peptization of the precipitate. The reaction was performed at room temperature.In the co-precipitation procedure aqueous NH4OH solution was added directly to the mixture solution of SnCl4d5H2O and SbCl3 until the pH of the mixture reach6–8,where pale yellow ATO hydroxide precipitate were produced.Peptization of ATO hydroxide with the aqueous solution containing oxalic acid gives a yellowish transparent sol.Finally ATO sol was heated and refluxed at608C for4h.2.2.Synthesis of hybrid organic–inorganic silica solThe hybrid organic–inorganic silica-based sols were synthesized as follows:First a mixture solution of tetrae-thoxysilane(TEOS),3-glycidoxypropyltrimethoxysilane (GPTS),isopropyl and alcohol in weight ratio1:1:2.5:3.5 was prepared.Then a suitable amount of deionized water (pH=1,by HCl addition)was added to the mixture solution. The mole ratio of TEOS and H2O is about1:6to1:8.The mixed solution was stirred and heated under reflux at808C for16h.The synthesized transparent hybrid silica sol was used as protecting component of nanocomposite thin film.2.3.Preparation of ATO/SiO2nanocomposite thin filmsA transparent functional gelled film was deposited from the mixture sol comprising the hybrid organic–inorganic silica sol and the ATO sol.Deposition was performed on the glass substrate at room temperature by a simple dip coating process.After being dried at room temperature the nano-composite gelled thin film was thermally densified at a temperature up to4008C in a reducing atmosphere containing N2and vapor of alcohol.2.4.InstrumentationThe Zeta potential measurement of the0.5wt.%ATO aqueous sol was carried out with a ZETASIZER3000HS A measuring system(MALVERN).0.1N HNO3was used to adjust the pH of reference ATO sol that does not contain oxalic acid.The X-ray diffractometer(XRD)was used for the structural characterization of the as-dried and thermally densified ATO–SiO2nanocomposite material.The micro-structure feature of nanocomposite gel film and annealed film were observed with a transmission electron microscope (TEM)(type JEM-2010).The sample for TEM study was prepared as follows:A droplet of mixed sol consisting of ATO colloidal sol and hybrid silica sol was dropped on a copper grid covered with organic film,and after solvents were vaporized a nanocomposite thin film was deposited on the copper grid.The chemical composition of annealed nanocomposite thin film was measured using an energy dispersive X-ray analysis system(EDS)equipped with a scanning electron microscope.Optical transmission was determined using a Varian Cary5E spectrophotometer in the wavelength range of300–2500nm.3.Results and discussion3.1.Surface adsorption studiesWhen oxalic acid was added to the ATO suspension the pH of suspension was adjust to2by the ionization of oxalic acid.Peptization with oxalic acid turns slowly the initial turbid ATO suspension into transparent stable sol.If without addition of oxalic acid ATO nanoparticles in the suspension will show aggregating behavior and begin precipitating at pH b5.The experimental result tells us that colloidal stability of ATO sol comes from addition of oxalic acid.Oxalic acid molecule acts as a surface-modifying agent and prevents aggregation of ATO particles.Fig.1shows the result of Zeta potential measurement at different pH level.The date shows that surface of ATO nanoparticles in aqueous sol is positively charged at pH\5without the addition of oxalic acid.The addition of oxalic acid decreases the Zeta potential of surface and changes the surface to a negative charge in the pH range2–4.According to the dissociation constant of oxalic acid the neutral molecules and negatively charged HO–(CO)2–OÀ1ions are predominant components in aqueous solution at2b pH b3.In initial suspension surface of ATO nanoparticles has a charge especially opposing the oxalic acid ions.The electrostatic force generated by the opposing charges will facilitate the ions transport stage of adsorption reaction.Now we assume that markedinteraction Fig.1.Zeta potential of ATO aqueous sol as a function of pH;0.5wt.% ATO content was used.X.C.Chen/Materials Letters59(2005)1239–1242 1240exist between oxalic acid ions and positive surface hydroxylgroups Q Sn–OH 2+or neutral surface hydroxyl groups Q Sn–OH.The oxalic acid ions can be preferentially adsorbed to the surface of ATO nanoparticles by hydrogen bond or Q Sn–O–C bond.The adsorbed ions neutralize surface positive charges and ultimately reverse the surface to a negative Zeta potential.Fig.1shows that the magnitude of negative Zeta potential is not large enough to stabilize the ATO nanoparticle electrostatically in sol.After oxalic acid was added to the suspension the transparent sol is found to remain stable almost infinitely at pH b 4.The only possible explanation is that effective dispersion mechanism comes from a combination of electrostatic and steric repulsion between oxalic acid ions that were adsorbed on surface of different ATO particles.3.2.XRD and EDS studiesFig.2shows XRD spectra of the ATO–silica nano-composite sample.The pattern (a)relates to the nano-composite gel obtained as dried at room temperature and the pattern (a)shows the presence of a very broad diffraction peak attributable only to cassiterite structure.The XRD patterns of nanocomposite samples show little difference between as-dried and thermally densified samples.Theresult indicates that ATO colloidal particles have developed a nanocrystal structure of cassiterite during sol preparation which contains a hydrothermal process at 608C.TheFig.2.XRD pattern of ATO–SiO 2composite gel:(a)as-dried at room temperature;(b)heat-treated at 5008C in air for 1h.Table 1Elemental concentration of ATO/SiO 2nanocomposite thin film Sample Atomic concentration,%V olume ratio,SiO 2/ATO O Si Sn Sb As-dried69.6917.2510.722.351.5Fig.3.Diffraction pattern and TEM image of ATO–SiO 2nanocomposite thin film as-dried at room temperature:(a)ED pattern;(b)TEMimage.Fig.4.Diffraction pattern and TEM image of ATO–SiO 2composite thin film thermal-treated at 3008C in reducing atmosphere for 2h:(a)ED pattern;(b)TEM image.X.C.Chen /Materials Letters 59(2005)1239–12421241hydrothermal process under atmosphere is also an effective method for promoting the crystallization of ATO nano-particles in the aqueous solution [14,15].The element contents in ATO–SiO 2film are shown in Table 1.Measured Si/Sn+Sb atom ratio of sample is about 1.3:1.The SiO 2/ATO volume ratio in the nanocomposite is calculated from the atom ratio and theory density.3.3.TEM and UV–Vis–Nir spectra studiesThe TEM image of as-dried ATO–SiO 2nanocomposite thin film is shown in Fig.3(b).We can observe that ATO nanoparticles are homogeneously dispersed in SiO 2-based amorphous matrix without any evidence of aggregation.ATO grains are found to have a size range of 3–5nm in diameter.Fig.3(a)shows a typical electron diffraction pattern of ATO nanocrystalline grain.Four electron dif-fraction (ED)rings can be indexed to the pattern of ATO with cassiterite structure.The result is in good agreement with XRD analysis.The structural change induced by thermal treatment of ATO thin film has been investigated.Fig.4shows the ED pattern and TEM image taken from ATO–SiO 2nanocomposite thin film which was annealed at 3008C in reducing atmosphere.The contrast morphology in this image shows some large crystal grains with diameter range from 20nm to 25nm.The ED pattern taken from the same sample contains some sharp spots resulting from thelarge crystallites.The observed results indicate that thermal treatment in reducing atmosphere can accelerate grain growth of ATO nanoparticles.The growth of crystal grain was accompanied by the disappearance of grain boundary and increased electrical conductivity and Nir-light reflec-tance of ATO film [1].The optical transmission spectra of ATO thin film deposited on the glass substrate of 1mm thick are shown in Fig.5.A high transmission of 85%is observed in the visible region.The reduction of transmission in the Nir wavelength arises from improved conductivity of nanocrystalline ATO particles that were heat-treated in the reducing atmosphere.4.ConclusionsThe transparent ATO–SiO 2nanocomposite thin films have been prepared successfully by the sol–gel method.The transmission of thin film is rather high in the visible region,range between 85%and 90%as well as the transmission in Nir region has been decreased to 41%.The thermal treatment in reducing atmosphere is an effective method for promoting crystalline grain growth of ATO nanoparticles.The oxalic acid is an excellent dispers-ing agent for ATO nanoparticle in the aqueous solution in pH range 2–4.References[1]G.Frank,E.Kauer,H.Kostlin,Thin Solid Films 77(1981)107.[2]M.S.Castro,C.M.Aldao,J.Eur.Ceram.Soc.20(2000)303.[3]O.Safonova,I.Bezverkhy,P.Fabrichnyi,M.Rumyantseva, A.Gaskov,J.Mater.Chem.7(1997)997.[4]S.Shanthi,C.Subramanian,P.Ramasamy,Cryst.Res.Technol.34(1998)1037.[5]A.E.Rakhshani,Y .Makdisi,H.A.Ramazaniyan,J.Appl.Phys.83(2)(1998)1049.[6]C.Goebbert,R.Nonninger,M.A.Aegerter,H.Schmidt,Thin SolidFilms 351(1999)79.[7]C.Terrier,J.P.Chatelon,J.A.Roger,Thin Solid Films 295(1997)95.[8]H.Ohsaki,Y .Kokubu,Thin Solid Films 351(1999)1.[9]M.A.Aegerter,N.Al-Dahoudi,J.Sol–Gel Sci.Technol.27(2003)81.[10]A.N.Banerjee,S.Kundoo,P.Saha,K.K.Chattopadhyay,J.Sol–GelSci.Technol.28(2003)105.[11]S.W.Kim,Y .W.Shin,D.S.Bae,J.H.Lee,J.Kim,H.W.Lee,ThinSolid Films 437(2003)242.[12]K.Abe,Y .Sanada,T.Morimoto,J.Sol–Gel Sci.Technol.26(2003)709.[13]J.Gallardo,A.Duran,I.Garcia,J.P.Celis,M.A.Arenas,A.Conde,J.Sol–Gel Sci.Technol.27(2003)175.[14]D.Y .Zhang,D.Z.Wang,G.M.Wang,Y .H.Wu,Z.Wang,Mater.Sci.Eng.,B,Solid-State Mater.Adv.Technol.8(1991)189.[15]S.J.Kim,S.D.Park,Y .H.Jeong,S.Park,J.Am.Ceram.Soc.82(1999)927.Fig.5.UV–Vis–Nir transmission spectra:(a)550nm thick ATO–SiO 2thin film which was coated on glass substrate;(b)glass substrate.X.C.Chen /Materials Letters 59(2005)1239–12421242。

Synthesis and characterization of metal complexes

Synthesis and characterization ofmetal complexesIntroductionMetal complexes have been actively studied due to their potential applications in various fields such as catalysts, materials, and medicine. The synthesis and characterization of metal complexes are fundamental steps towards understanding their properties and behaviors. In this article, we will discuss some of the methods and techniques used for synthesizing and characterizing metal complexes, as well as their applications.Synthesis of metal complexesThe synthesis of metal complexes can be achieved through various methods such as salt metathesis, ligand exchange, and coordination polymerization. Salt metathesis involves replacing one metal ion in a salt with another metal ion. Ligand exchange involves replacing one ligand in a metal complex with another ligand. Coordination polymerization involves the combination of metal ions and organic ligands to form a three-dimensional network structure.One example of a metal complex synthesis method is ligand exchange. In this method, a metal complex with a specific ligand is reacted with a new ligand to form a different metal complex. For example, the reaction between copper(II) sulfate and sodium acetate results in the formation of copper(II) acetate.CuSO4 + 2NaOAc → Cu(OAc)2 + Na2SO4Another example is coordination polymerization. In this method, metal ions and organic ligands are combined in a solution to form a solid network structure. For example, the reaction between zinc(II) nitrate and 2,6-naphthalenedicarboxylic acid results in the formation of a porous coordination polymer called MOF-5.Zn(NO3)2 + H2bdc → Zn4O(H2bdc)3 + 2HNO3Characterization of metal complexesCharacterization of metal complexes is important in understanding their physical and chemical properties. Techniques such as X-ray crystallography, infrared spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy can be used to identify the structure and composition of metal complexes.X-ray crystallography involves the analysis of crystals using X-rays to determine the positions of atoms in a molecule. It provides information on the three-dimensional structure of a metal complex. Infrared spectroscopy involves the measurement of the energy absorbed by a molecule due to vibrations of its chemical bonds. It provides information on the functional groups present in a metal complex. NMR spectroscopy involves the measurement of the absorption of energy by nuclei in an external magnetic field. It provides information on the electronic environment surrounding metal ions in a complex.Applications of metal complexesMetal complexes have a wide range of applications in various fields. They can act as catalysts in chemical reactions, for example, the use of palladium complexes as catalysts in Suzuki coupling reactions. They can also be used as materials in the form of coordination polymers for gas storage or catalysis. In medicine, metal complexes can be used as contrast agents in imaging techniques or as anticancer drugs.ConclusionIn summary, the synthesis and characterization of metal complexes are important for understanding their properties and behavior. Various methods and techniques can be used for synthesizing and characterizing metal complexes. Applications for metal complexes are diverse and extend to fields such as catalysis, materials, and medicine. With continued research and development, metal complexes are expected to play an increasingly important role in these fields.。

聚合松香基环氧树脂的合成与表征

第28卷第5期2008年10月林　产　化　学　与　工　业Che m istry and I ndustry of Forest Pr oducts Vol .28No .5Oct .2008聚合松香基环氧树脂的合成与表征收稿日期:2007-11-19 基金项目:广东省关键领域重点突破项目(2006A 25002002);广东省自然科学基金研究团队项目(E06200692) 作者简介:黄活阳(1974-),男,江西东乡人,博士,主要从事天然产物开发与利用研究;E 2ma il:i m perialcrown@s ohu .com 3通讯作者:哈成勇,研究员,博士生导师,博士,研究领域:天然产物开发与利用。

HUANG Huo 2yang 黄活阳1,2,哈成勇13,李因文1,2,沈敏敏1(1.中国科学院广州化学研究所;中国科学院纤维素重点实验室,广东广州510650;2.中国科学院研究生院,北京100039)摘　要:　以聚合松香为原料,与环氧氯丙烷进行酯化反应、闭环反应,合成了聚合松香基环氧树脂,并对产物的红外光谱和核磁共振谱进行了解析。

重点讨论了酯化反应、闭环反应影响因素对产物性能的影响。

当适宜的反应条件为:聚合松香与环氧氯丙烷物质的量比约为1∶8,反应温度75℃,反应总时间8h,合成的环氧树脂的环氧值为0.19mol/100g,黏度(30℃)为30.8Pa ・s,酸值为0.2mg/g 。

关键词:　聚合松香;环氧树脂;环氧值;黏度中图分类号:T Q351.47 文献标识码:A 文章编号:0253-2417(2008)05-0040-05Synthesis and Characterizati on of Poly merized Rosin Epoxy ResinHUANG Huo 2yang 1,2,HA Cheng 2yong 1,L I Yin 2wen 1,2,SHEN M in 2m in 1(1.Guangzhou I nstitute of Che m istry,Chinese Acade my of Sciences,Key Lab .of Cellul ose and L ignocellul osics Che m istry,Guangzhou 510650,China;2.Graduate School of Chinese Acade my of Sciences,Beijing 100039,China )Abstract:Poly merized r osin epoxy resin was synthesized by esterificati on and ring 2cl osing reacti on of poly merized r osin and ep ichl or ohydrin .The p r oduct was identified by FT 2I R and 1H NMR s pectr ometries .The influencing fact ors of p r oduct p r operties were discussed e mphatically .The suitable reacti on conditi ons were as f oll ows:mole rati o of poly merized r osin t o ep ichl or ohydrin 1∶8,reacti on temperature 75℃,reacti on ti m e 8h .The p r oduct had foll owing p r operties:epoxy value 0.19mol/100g,viscosity (at 30℃)30.8Pa ・s,and acid value 0.2mg/g .This novel epoxy r osin had a rigid polycyclic structure,which would enrich the varieties of epoxy resin,widen the app licati on range of r osin and increase the additi onal value of r osin .Key words:poly merized r osin;epoxy resin;epoxy value;viscosity我国是林产资源大国,松香资源非常丰富,年产量约为70万吨。

Synthesis characterization of near-infrared fluorescent andmagnetic iron zero-valent nanoparticles

Synthesis and characterization of near-infrared ﬂuorescent and magnetic iron zero-valent nanoparticlesNagore Pérez a ,Leire Ruiz-Rubio a ,*,JoséLuis Vilas a ,b ,Matilde Rodríguez a ,Virginia Martinez-Martinez a ,Luis M.León a ,baDepartamento de Química Física,Facultad de Ciencia y Tecnología,Universidad del País Vasco/Euskal Herriko Unibertsitatea (UPV/EHU),Apdo 644,Bilbao 48080,Spain bBasque Center for Materials,Applications and Nanoestructures (BCMATERIALS)Parque Tecnológico de Bizkaia,Ed 500,Derio 48160,SpainA R T I C L E I N F OArticle history:Received 4May 2015Received in revised form 4September 2015Accepted 6September 2015Available online 9September 2015Keywords:Iron zero valent nanoparticles Fluorescent MagneticPolyethylenglycolA B S T R A C TPolyethylene glycol coated iron nanoparticles were synthesized by a microemulsion method,modi ﬁed and functionalized.The polymer coating has a crucial role,preventing the iron oxidation and allowing the functionalization of the particles.The nanoparticles were characterized and their magnetic properties studied.A photochemical study of the iron nanoparticles conjugated with a near-infrared ﬂuorescent dye,Alexa Fluor 660,con ﬁrmed that the ﬂuorescent dye is attached to the nanoparticles and retains its ﬂuorescent properties.The bioimages in red and near-infrared (NIR)region are favourable due to its minimum photodamage and deep tissue penetration.The nanoparticles obtained in this study present a good magnetic and ﬂuorescent properties being of particular importance for potential applications in bioscience.ã2015Elsevier B.V.All rights reserved.1.IntroductionA broad range of nanosized inorganic particles,including magnetic nanoparticles and quantum dots,have been extensively investigated because of their unique optical,electrical and magnetic properties [1–5].Moreover,magnetic iron oxide colloids have been successfully used as magnetic resonance imaging (MRI)contrast agents and for cancer hyperthermia therapy [6–9].The shape,size and size distribution of the magnetic materials are the key factors in determining their chemical and physical properties.Thus,the development of size and shape-controlled magnetic materials is crucial for their application [3,9].So far,the most widely used and studied magnetic material is iron oxide,in the form of magnetite (Fe 3O 4)and maghemite (g -Fe 2O 3).Elemental iron has a signi ﬁcantly higher magnetic moment than its oxides.Moreover,elemental iron is the most useful among the ferromagnetic elements;it has the highest magnetic moment at room temperature (218emu g À1in bulk),and a Curie temperature which is high enough for the majority of practical applications.However,obtaining Fe nanoparticles,relatively free of oxide (usually Fe 3O 4),is still a challenge,to a large extent,not overcome [10–13].Besides the properties of the metallic core,the coating of the nanoparticles could determinate or improve the uses of this kind of materials.For example,functionalized magnetic nanoparticles have been employed for site-speci ﬁc drug delivery [14]or treatment waterwaste [15,16].The variety of potential coating materials is continuously increasing with the development of new polymeric materials.However,polyethylene glycol (PEG)could be considered one of the most suitable polymer coatings for nanoparticles designed to be used in biomedicine.PEG is a water-soluble polymer with a low toxicity and antibiofouling properties that make it an appropriate candidate for several bioscience related applications [17,18].PEG chains attached to a nanoparticle surface exhibit a rapid chain motion,this could contribute to the good physiological properties of the PEGylated nanoparticles [19]for imagining and therapy application.Also,successful studies haven been devoted to PEG-PLA coated nano-particles for drug delivery [20,21].PEG grafted onto the surface of nanoparticles provides steric stabilization that competes with the destabilizing effects of Van der Waals and magnetic attraction energies.Thus,there is a growing demand for improved methods for the synthesis and characterization of polyethylene glycol (PEG)derivatives [22–25].Especially,polyethylene glycols (PEGs)of long polymeric chains have found signi ﬁcant applications in the structure stabilization [26–28].Finally,the polymeric coatings of the nanoparticles could be conjugated with antibodies or ﬂuorescent dyes adding different*Corresponding author.E-mail address:leire.ruiz@ehu.eus (L.Ruiz-Rubio)./10.1016/j.jphotochem.2015.09.0041010-6030/ã2015Elsevier B.V.All rights reserved.Journal of Photochemistry and Photobiology A:Chemistry 315(2016)1–7Contents lists available at ScienceDirectJournal of Photochemistry and Photobiology A:Chemistryj o u rn a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j p h o t o c h emproperties to the system[29–31].That is,ﬂuorescent-magnetic nanoparticles could be designed as an all-in-one diagnostic and therapeutic tool,able to visualize and simultaneously treat various diseases.Fluorescence imaging is one of the most powerful techniques for monitoring biomolecules in living pared with ﬂuorescent imaging in the visible region,biological imaging in red and near-infrared(NIR)region is favourable due to its minimum photodamage,deep tissue penetration,and minimum background autoﬂuorescence caused by biomolecules in living systems. Therefore,chromophores with emission in red or near-infrared region have been paid increasing attention in recent years[32,33].However,there is a speciﬁc difﬁculty in the preparation of ﬂuorescent magnetic nanoparticles due to the risk of quenching of theﬂuorophore on the particle surface by the magnetic core.This problem could be solved by coating the magnetic core with a stable isolating shell prior to the introduction of theﬂuorescent molecule or by attaching an appropriate spacer to theﬂuorophore.Most ﬂuorescent magnetic nanoparticles thus have a core-shell struc-ture.Several studies have been devoted to develop iron oxide nanoparticles conjugated withﬂuorescent dyes,in order to obtain dual-responsive nanoparticles,with magnetic andﬂuorescent response[31].Often,the methods are time consuming due to the many synthetic steps or the fact that gold or silica precoating is required to protect the iron oxide nanoparticles previous to their functionalization[34–36].Also,there is a signiﬁcant lack on studies about iron nanoparticles functionalized withﬂuorophores [37].The aim of this work is to synthesize iron nanoparticles coated with a PEG-derivative and functionalized with aﬂuorescent dye.The iron core of the nanoparticles will provide higher magnetization saturation than iron oxides,the PEG not only protects the metallic core but also adds interesting properties to biologically related applications.The selectedﬂuorescent dye, imaging in red and near-infrared,is highly adequate for an application in medicine owing to its low photodamage.So,the obtained nanoparticles could be highly promising materials for combined MR/Optical imaging applications.2.Materials and methods2.1.ChemicalsAll chemicals were reagent grade and used without puriﬁcation. Ferrous chloride tetrahydrate(FeCl2Á4H2O),sodium borohydride (NaBH4)and cyclohexan solvent were purchased from Sigma–Aldrich.Methanol and chloroform were purchased from Panreac and Lab-Scan,respectively.Polyethylene glycol(PEG)of1000g molÀ1molecular weight and methoxy polyethylene glycol(mPEG) of2000g molÀ1molecular weight were obtained from Sigma–Aldrich.Deionized Millipore Milli-Q water was used in all experiments.Alexa Fluor1660Protein Labeling Kit was purchased from Invitrogen.2.2.Synthesis of iron nanoparticlesThe preparation of PEG-stabilized nanoscale zero-valent iron nanoparticles was carried out via a controlled microemulsion method.The microemulsion synthetic methodology makes use of a biphasic heterogeneous solution of water-in-oil in which iron precursors are stirred.Water droplets are used as nucleation sites for the formation of nanoparticles,often in the presence of surfactant molecules dispersed in the oil,essentially forming micelles.The reactions were carried out at room temperature using a single micellar system(sample FePEG-04)and two micellar systems(sample FePEG-02).The procedure followed in theﬁrstcase is described here.A surfactant solution prepared by dissolving31.5g of polyeth-ylene glycol in105mL of cyclohexane was maintained understirring and degassed for10min under N2atmosphere.Next,6mLof0.33M FeCl2Á4H2O were added to the surfactant solution,stirred and degassed for10min.Metal particles were formed inside thereverse micelles via reduction of the metal salt using an excess ofNaBH4(6mL, 1.76M).After a few minutes,the reaction wasquenched by adding50mL of chloroform and50mL of methanol.The black precipitate was recovered with a permanent magnet,washed several times with methanol and dried under vacuum.The same procedure was carried out in the synthesis performedby two micellar systems with the only difference that the reducingagent(NaBH4),was added in aqueous solution instead of in solidform.This solution,when added toﬂask reaction,will result thesecond micellar system.Deﬁnitely,the method involves mixingtwo microemulsions:one containing the metal salt and the otherthe reducing agent;due to collision and coalescence of the dropletsthe reactants are brought into contact and react to form thenanoparticles.Polyethylene glycol methyl ether(mPEG)shows greaterversatility in functionalization,which increases the potentialapplications of nanoparticles.Speciﬁcally,this will be thederivative chosen to functionalize nanoparticles.The syntheseswith this surfactant were carried out at room temperature using asingle-micellar system,0.40g of iron salt,0.20g of the reducingagent,105cm3of cyclohexane and6.0g of water.The concentrationof surfactant in this system was0.095M.2.3.Functionalization of nanoparticles and labelling withﬂuorescentdyeThe incorporation of theﬂuorescent molecule to the nano-particles consists of several steps.Firstly,functionalized nano-particles are synthesized and then theﬂuorophore is anchored.After that the labelled nanoparticles must be puriﬁed to take outthe excess dye by size-exclusion chromatography.2.3.1.Modiﬁcation of mPEGPolyethylene glycol methyl ether(mPEG)of molecular weight2000g molÀ1wasﬁrstly treated to obtain the aldehyde-derivativeby oxidation of the hydroxyl end groups by dimethylsulfoxide(DMSO)and acetic anhydride at room temperature.Then them-PEG-amine was obtained by the method described by Harriset al.[38],via reduction of the aldehyde groups using sodiumcyanoborohydride in methanol at room temperature.2.3.2.Synthesis of nanoparticles with mPEG-NH2and PEGThe synthesis of nanoparticles was performed by the methodpreviously described for one micellar system.Owing to the smallamount of materialﬂuorescent necessary,the appropriate amountof mPEG-NH2was used,and the rest was PEG surfactant,as alreadyshown,to provide adequate protection to the nanoparticles.The surfactant consisted of a mixture of7.5g of PEG and217mgof mPEG-NH2,amounts required to have a total surfactantconcentration of0.30M.belling of nanoparticlesThe interaction of metal nanoparticles withﬂuorophores nearits surface affects the intensity of their emission being critical thedistance between theﬂuorophore and the surface of thenanoparticle so that theﬂuorescence is quenched when thedistance is too short.For this study Alexa Fluor660was used.Thisis a succinimidyl ester of Alexa Fluor which exhibits bright ﬂuorescence and high photostability characteristics allowing us to2N.Pérez et al./Journal of Photochemistry and Photobiology A:Chemistry315(2016)1–7capture images that were previously unattainable with conven-tional ﬂuorophores.Moreover it provides an ef ﬁcient and convenient way to selectively link to primary amines.On the other hand,its absorption and ﬂuorescence bands are far from those of the nanoparticles,so that the spectral overlapping is negligible.The PEGylated nanoparticles were ﬂuorescently labelled by reaction with Alexa Fluor 660carboxylic acid succinimidyl ester which formed a chemical bond with the NH 2group of mPEG-NH 2.For that,the procedure established by Invitrogen [39]was followed.Brie ﬂy,a solution of sodium bicarbonate was added to the nanoparticles suspension in order to reach a pH between 7,5and 8,5since succinimidyl esters react ef ﬁciently at this pH range.The reactive dye was added to the solution and the reaction mixture was stirred for 1h at room temperature.Separation of the labelled nanoparticles from dye which has remained unreacted was carried out using a puri ﬁcation column containing the Bio-Rad BioGel P30resin.2.4.Characterization of nanoparticlesThe crystallite phase of the coated nanoparticles was identi ﬁed by recording X-ray diffraction patterns (XRD)using a Bragg –Brentano u /2u Philips diffractometer.Size and shape of nanoparticles were studied by transmission electron microscopy (TEM).Measurements were carried out using a Philips CM 200equipment operating at an accelerating voltage of 200KV.For this,a drop of dilute methanol solution of the nanoparticles was placed onto a copper grid coated with carbon ﬁlm with a Formvar membrane and allowed to air dry before being inserted into the microscope.Magnetic properties were studied with a vibrating sample magnetometer (VSM).57Fe Mössbauer spectroscopy measurements were carried out at room temperature (RT)in transmission geometry using a conventional spectrometer with a 57Co-Rh source.Reported isomer shift (d )and internal magnetic hyper ﬁne ﬁeld (BHF)values are relative to metallic Fe at room temperature.The UV –vis absorption spectra were recorded on a Varian double beam spectrophotometer (Cary 4E)in transmittance mode,in the region of 200–900nm.The ﬂuorescence spectra were performed on a SPEX ﬂuorimeter (Fluorolog 3-22).The emission spectra were recorded in the 250–800nm range,by exciting at different wavelengths,depend-ing on the sample.Fluorescence single-particle measurements were performed in a time-resolved ﬂuorescence confocal microscope (model MicroTime 200,PicoQuant).Fluorescence lifetime images (FLIM)are processed with ShymPhotime software (Picoquant)by sorting all photons of one pixel into a histogram and ﬁtted to an exponential decay function to extract lifetime information;the procedure was repeated for every pixel in the image.A 640nm pulsed laser diode,with 70ps pulses was used as excitation source.Spectra were recorded by directing the emission beam to an exit port,where a spectrograph (model Shamrock 300mm)coupled to a CCD camera (Newton EMCCD 1600Â200,Andor)were mounted.3.Results and discussion3.1.Spectroscopic and crystallographic characterizationPolyethylene glycol and polyethylene glycol methyl ether coated iron nanoparticles were characterized by XRD measure-ments as shown in Fig.1.The spectrum of PEG coated samples obtained by one or two micellar systems (Fig.1a)shows three characteristic broad peaks at 2u =44.81 ,65.07 and 82.49 ,which correspond to the (110),(200),and (211)families of planes of the bcc lattice reported for the a -Fe phase.The dimension of the crystallites,D hkl ,was estimated by Scherrer equation in 27.8nm.The nanoparticles obtained with mPEG as surfactant present a diffractogram with a peak of high intensity at 2u =45 ,corre-sponding to the bcc lattice (Fig.1b).This kind of diffractogram is characteristic of samples with low crystallinity and very polydis-perse sizes.From TEM images and histograms (Fig.2),it can be concluded that each Fe/PEG unit consists in a spherical Fe core with an average size of 3.8nm and its own polymeric coating of about 6nm.According to XRD results,the FemPEG-01sample was very polydisperse and it was very dif ﬁcult to obtain a mean diameter.In general,the size of the nanoparticles was between 10and 20nm.The values obtained are similar to those obtained when using nonylphenypentaethoxylated (NP5)[40]as surfactant whose value was around 10nm (Fe core 7.5nm and polymeric shell 2.8nm).PEG provides a thicker coating shell than NP5,probably due to the different molecular weight of both surfactants.3.2.Magnetic propertiesMagnetization vs applied ﬁeld hysteresis loops were measured using VSM to assess the magnetic properties of the synthesized nanoparticles.The saturation magnetization values were normal-ized to the mass of nanoparticles to yield the speci ﬁc magnetiza-tion,M s (emu g À1).Fig.1.X-ray diffractograms of the synthesized iron nanoparticles:(a)Polyethylenglycol coated samples and (b)polyethylene glycol methyl ether coated sample.N.Pérez et al./Journal of Photochemistry and Photobiology A:Chemistry 315(2016)1–73Fig.3shows the magnetic hysteresis loops of the samples at room temperature.The saturation magnetization of FePEG nano-particles is shown in Table 1.The saturation magnetization arises from both the iron core (218emu g À1),and the iron oxide shell (for Fe 3O 480–92emu g À1),based on the relative weight percentage of iron,iron oxide and non-magnetic coatings on the particle surface.For particles having a similar shell thickness,the weight ratio of the iron core to the iron oxide shell is greater for large particles than for small particles.All the samples have coercitivity less than 15mT and a remanence less than 25A m 2kg À1.This suggested that the particles could aggregate after the removal of the external ﬁeld due to the remaining magnetization.57Fe Mössbauer spectroscopy measurements were carried out for the FePEG-04sample due to it has the best magneticpropertiesFig.2.Micrographs of (a)FePEG-02,(b)FePEG-04and (c)FemPEG-01samples.Fig.3.Magnetization curves.Table 1Saturation magnetization (Ms),coercitive ﬁeld (Hc)and remanent magnetization.MuestraMs (A m 2kg À1)Hc (mT)Mr (A m 2kg À1)FePEG-0211615.319.9FePEG-0413513.221.3FemPEG-0110816.819.2Fig.4.RT Mössbauer spectrum for FePEG-04sample.4N.Pérez et al./Journal of Photochemistry and Photobiology A:Chemistry 315(2016)1–7of the studied samples(Fig.4).The RT Mössbauer spectrum qualitatively consist in a sextet(62%of the total area),attributed to bcc Fe(BHF=32.89T and d=À0.106mm sÀ1)coupled to a doublet corresponding to Fe2+or Fe3+.The appearance of both signals would indicate the occurrence of an oxidation process leading to the formation of magnetite(Fe3O4).Any other ordered phase is not observed since more sextets were not found.The iron oxides present in these samples are not magnetically ordered due to the absence of further sextets.This was conﬁrmed by the XPS(Apendix A,Fig.S5)where the peaks at710.30,718.98(small peak)and 723.32eV represent the binding energies of Fe(2p3/2)shake-up satellite2p3/2and2p1/2,respectively.In addition,a small shoulder at705,87eV suggest the peak of2p3/2of zero-valent iron[41].All the studied systems present a high reproducibility as could be conﬁrm in the supporting information(Supporting information (Appendix A))in which the obtained X-ray difratograms and magnetization curves are shown.3.3.Fluorescent measurementsIn this section the photophysical study of the nanoparticlesconjugated with theﬂuorescent dye is described.Fig.5shows the height-normalized absorption spectrum of the Alexa Fluor1 660and the labelled sample.As can be seen,the absorption spectra are almost identical and show the principal absorption band centred at668nm,indicating the presence of the dye in the nanoparticles.Furthermore,a weak band in the UV region of the spectrum,around250nm,could include iron oxides such as hematite,magnetite or maghemite[42].Fig.6shows the height-normalizedﬂuorescence spectra of the fraction with the highest content of nanoparticles with dye in suspension at two excitation wavelengths,250and620nm.On the one hand,when the excitation of the sample takes place directly to the absorption band of the dye(620nm,see Fig.5)the emission band is obtained at696nm,emission band typical of Alexa Fluor 6601dye,indicating its presence in the particles.In order to compare theﬂuorescence efﬁciency of Alexa660dye in solution and anchored at the nanoparticles,the ratio between the ﬂuorescence intensity and the absorbance of the sample at the excitation wavelength is analysed(Fig.S6).In this way and assuming a quantum yield of around0.37for Alexa660in aqueous solution[36],an estimated quantum yield of around0.13is obtained for the dye at the nanoparticles in suspension On the other hand,when the excitation wavelength wasﬁxed at250nm (absorption attributed mainly to the iron oxides present in the nanoparticles)the obtained band at390nm can be attributed to the typical emission of nanoparticles of iron oxide present in the sample.In addition,the dye emission band is also present.Although the absorption andﬂuorescence spectroscopictechniques indicate the presence ofﬂuorescence dye in thesuspension of nanoparticles,to conﬁrm the anchorage to thenanoparticles surface confocalﬂuorescence time resolved micros-copy measurements were carried out.This technique allows thestudy of theﬂuorescent properties of the dye anchored onto singlenanoparticles[43].In this way it can be obtained informationabout lifetimes of a single particle(Fig.7),and also,through a CCDcamera,a spectrum of theﬂuorescence in single particle can beobtained(Fig.8).So,by positioning the excitation laser(640nm)in the centre ofeach nanoparticle,theﬂuorescence spectrum of the anchored dyenanoparticle is obtained(Fig.8).In addition,theﬁgure includes thespectrum of dye in solution measured at the same conditions.Themaximum ofﬂuorescence are696nm for dye and687nm for thedye anchored to nanoparticles.The displacement of the maximumtowards lower wavelength,is a typical effect of dyes adsorbed insurfaces,as the case of the iron nanoparticles.Fig.9shows theﬂuorescence decay curves obtained by confocalmicroscopy for the dye in solution and labelled dye in eachnanoparticle and respective histograms.The half lifetime of free dye presents monoexponencialbehaviour,with a value ofﬂuorescence life time t=1.8ns,while the conjugated nanoparticles presents a biexponencial behaviourwith:life time t1%0.1–0.5ns y t2=1.5–1.7ns(Fig.9).These values have been obtained after the analysis of,at least,10individualparticles.The short half lifetime,around0.1–0.6ns can be attributed tothe light scattered by the nanoparticle itself and the obtained longhalf life time(t2=1.5–1.7)is attributed to anchored dye to nanoparticle surface.AbsorbanceWavelength (nm)Fig.5.Height-notmalized absorption spectra of Alexa Fluor660dye and ironlabeled nanoparticles in aqueous buffer suspension.FluorescenceIntensity(a.u.)Wavelength (nm)Fig.6.Height-normalizedﬂuorescence spectra of iron nanoparticles in aqueousbuffer suspension at excitation wavelengths of250and620nm.Fig.7.Fluorescence microscopy image of single particles.N.Pérez et al./Journal of Photochemistry and Photobiology A:Chemistry315(2016)1–75The slight decrease of the long lifetime of anchored dye regarding the diluted suspension of the nanoparticle can be attributed to the dye quenching due to the presence of iron oxide.Confocal ﬂuorescence microscopy con ﬁrmed that the dye is labelled onto nanoparticles and maintains its ﬂuorescent proper-ties.Therefore,the trajectory of these nanoparticles may be monitored by ﬂuorescence microscopy under red excitation in vitro or in vivo experiments.4.ConclusionsIn this study,iron nanoparticles coated with PEG and mPEG were prepared and characterized.The nanoparticles present high magnetic susceptibility and sizes between 10and 15nm.It is noteworthy that the synthesized nanoparticles are mainly zero-valent iron.The FemPEG nanoparticles were successfully functionalized and conjugated with a ﬂuorescent dye.Thus,amine-reactive N -hydroxysuccinimidyl ester of Alexa Fluor 660dye was conju-gated to the nanoparticle surface.This dye produces bright far red ﬂuorescence emission with a peak at 690nm under red excitation light (in the clinic window).Studies of confocal ﬂuorescence microscopy con ﬁrmed that the ﬂuorescent dye is attached to the nanoparticles and retains itsﬂuorescent properties which could make possible to monitor the course of in vitro or in vivo samples using ﬂuorescent microscopy red under excitation.The magnetic properties of synthesized nanoparticles added to its ﬂuorescent response result in a suitable material for be detected by both magnetic and ﬂuorescent techniques for combined MR/Optical imaging applications.AcknowledgementsAuthors thank the Basque Country Government for ﬁnancial support (ACTIMAT project,ETORTEK programme IE10-272)(Ayu-das para apoyar las actividades de los grupos de investigación del sistema universitario vasco,IT718-13and IT339-10).Technical and human support provided by SGIKER (UPV/EHU,MICINN,GV/EJ,ERDF and ESF)is gratefully acknowledged.V.M.M.acknowledges the Ramon y Cajal contract with the Ministerio de Economía y Competitividad,(RYC-2011-09505).Appendix A.Supplementary dataSupplementary data associated with this article can be found,in the online version,at /10.1016/j.jphotochem.2015.09.004.References[1]I.L.Medintz,H.T.Uyeda,E.R.Goldman,H.Mattoussi,Quantum dotbioconjugates for imaging,labelling and sensing,Nat.Mater.4(2005)435–446./10.1038/nmat1390.[2]X.Michalet,F.F.Pinaud,L.A.Bentolila,J.M.Tsay,S.Doose,J.J.Li,et al.,Quantumdots for live cells,in vivo imaging,and diagnostics,Science 307(80)(2005)538–544,doi:/10.1126/science.1104274.[3]K.L.Kelly,E.Coronado,L.L.Zhao,G.C.Schatz,The optical propierties of metalnanoparticles:the in ﬂuence of size,shape,and dielectric environment,J.Phys.Chem.B 107(2003)668–677,doi:/10.1021/jp026731y .[4]K.Woo,J.Hong,S.Choi,H.-W.Lee,J.Ahn,C.S.Kim,et al.,Easy synthesis andmagnetic properties of iron oxide nanoparticles,Chem.Mater.16(2004)2814–2818,doi:/10.1021/cm049552x .[5]W.S.Seo,H.H.Jo,K.Lee,B.Kim,S.J.Oh,J.T.Park,Size-dependent magneticproperties of colloidal Mn3O4and MnO 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bare and coated zero valent iron nanoparticles for lindane degradation from its by-product monitorization,Chemosphere 93(2013)1324–1332,doi:/10.1016/j.chemosphere.2013.07.050.Fig.8.Fluorescence spectrum of a single particle (red curve)and a diluted dye solution (black curve)registered in time-resolved ﬂuorescence confocal microscope at excitation wavelength of 640nm.(For interpretation of the references to colour in this ﬁgure legend,the reader is referred to the web version of thisarticle.)Fig.9.Fluorescence decay curves of Alexa Fluor 660and two different regions.6N.Pérez et al./Journal of Photochemistry and Photobiology A:Chemistry 315(2016)1–7。

N掺杂K2Ti6O13电子结构和光学性质的第一性原理计算

D O I :10.3969/j.i s s n .1001-5337.2023.4.087 *收稿日期:2022-06-20基金项目:山东省高等学校青创人才引育计划项目.第一作者:刘保通,男,1980-,实验师;研究方向:物理学;E -m a i l :l b a o t o n g@q f n u .e d u .c n .通信作者:路洪艳,女,1982-,博士,教授;研究方向:凝聚态理论与计算;E -m a i l :h yl u @q f n u .e d u .c n .N 掺杂K 2T i 6O 13电子结构和光学性质的第一性原理计算*刘保通①, 李牙平②, 路洪艳②(①曲阜师范大学网络信息中心;②曲阜师范大学物理工程学院,273165,山东省曲阜市) 摘要:采用第一性原理计算,对N 掺杂前后六钛酸钾(K 2T i 6O 13)的电子结构和光学性质进行了研究.结果分析表明:N 掺杂后K 2T i 6O 13的带隙值略有减小且在其禁带中引入了杂质能级,由于杂质能级的作用使得N 掺杂后的K 2T i 6O 13吸收带边红移至可见光区,并在可见光范围内吸收强度出现明显的增强.关键词:N 掺杂;电子结构;光学性质;吸收红移中图分类号:O 469 文献标识码:A 文章编号:1001-5337(2023)04-0087-040 引言目前环境污染和能源短缺日益加剧,太阳能作为一种清洁可持续的绿色能源受到人们的广泛关注.其中半导体光催化技术逐渐被应用于太阳能转化和利用中[1-3].六钛酸钾(K 2T i 6O 13)是一种优异的光催化材料[4-6],因其具有优异的物理化学性能和较低的制备成本[7-9],引起研究人员研究的热潮.然而,K 2T i 6O 13带隙值较大(3.48e V )[10],对太阳光的利用率极低.为了使K 2T i 6O 13对太阳光的响应范围增大,同时,抑制光生载流子复合,有必要对其进行一定的改性研究.大量的报道指出通过N 掺杂取代T i O 2中的O可实现T i O 2对可见光的响应[11-13],基于此,本研究通过N 掺杂取代K 2T i 6O 13中的O 对K 2T i 6O 13进行改性.本文应用第一性原理计算,研究N 掺杂前后钛酸钾电子结构和光学性质的变化,探讨N 掺杂对K 2T i 6O 13光吸收能力的影响及其改性的内在机理.1 理论模型与计算方法图1为N 掺杂前后K 2T i 6O 13(1ˑ2ˑ1)超胞结构模型.本征的K 2T i 6O 13是单斜晶系,空间群为C 2/m ,每个晶胞由2个K 2T i 6O 13分子单元组成,共有42个原子[14],原子坐标见文献[15].在N 掺杂模型中,用一个N 原子取代K 2T i 6O 13中的一个O 原子.图1 (a )K 2T i 6O 13(1ˑ2ˑ1)超胞结构 (b )N 掺杂的K 2T i 6O 13超晶胞结构本文的计算通过M a t e r i a l sS t u d i o 软件中的C a s t e p 模块完成[16].首先,对K 2T i 6O 13的超胞结构进行结构优化;其次,对K 2T i 6O 13的电子结构和光学性质进行计算并且分析.本文中电子间的交换关联能采用的是基于密度泛函理论下的广义梯度近似中的P W 91形式,平面波截断能设为340e V ,布里渊区的积分采用2ˑ3ˑ3的k 点设置.计算中考虑的各元素价电子为O :2s 22p 4,T i :3s 23p 63d 24s 2,K :3s 23p 64s 1和N :2s 22p 3.2 结果与分析2.1 几何优化结果N 掺杂前后K 2T i 6O 13超胞模型几何优化后得到的晶胞参数见表1.由表1可知,本征的K 2T i 6O 13第49卷第4期2023年10月曲阜师范大学学报J o u r n a l o f Q u f u N o r m a l U n i v e r s i t yV o l .49 N o .4O c t .2023Copyright ©博看网. All Rights Reserved.晶格基矢与实验值[10]和其他理论计算值[17]相符,这证明我们的计算方法是正确合理的.N 掺杂后的K 2T i 6O 13的晶格基矢和体积都有增加,这主要因为N 原子的半径比O 原子的半径大且T i -N 键的键长较T iO 键的键长长.表1 几何优化后N 掺杂前后K 2T i 6O 13的超晶胞参数和键长P a r a m e t e r sA v e r a g e b o n d l e n gt h /Åa /Åb /Åc /ÅV /Å3T i O T i N K 2T i 6O 13[17]15.8507.6169.2431098.6372.004N -d o pe d 15.8207.6349.2521100.1572.1042.2 电子结构在图2中可以看到N 掺杂前后K 2T i 6O 13的能带结构.据图2(a )知,K 2T i 6O 13的带隙为2.834e V ,这和已有的计算结果相符[17].与实验值3.48e V [10]相比,计算值偏小,但计算结果的相对值是有意义的,可以将其视为一种有效的近似方法从而对材料的电子结构进行分析.从图2(b)可以看出,经N 掺杂后K 2T i 6O 13带隙变为2.815e V.与本征的K 2T i 6O 13相比,它的带隙值降低了0.019e V ,这有利于其光吸收边的红移.且其价带顶附近出现了杂质能级,杂质能级与导带底的能量差为2.410e V ,因此,N 的掺杂将实现K 2T i 6O 13对可见光的吸收.此外,此杂质能级为受主能级可抑制载流子的复合,进而提高其光催化性能.图2 (a )K 2T i 6O 13和(b )N 掺杂K 2T i 6O 13的能带结构图3为N 掺杂前后K 2T i 6O 13的态密度图.由图3(a )可知,纯K 2T i 6O 13的价带和导带基本上是由O2p 和T i 3d 态组成,由此可以看出O 和T i 之间可能存在强烈的相互作用.K 离子在T i O 6八面体组成的隧道状结构处以游离态存在,T i 和O 间的强相互作用使得K 2T i 6O 13结构具有很强的稳定性[15,18,19].由图3(b )和图3(c )可知,N 掺杂后在K 2T i 6O 13价带顶附近出现的杂质能级主要由O2p ,T i 3d 和N2p 轨道杂化而成.图3 (a )K 2T i 6O 13的分态密度;(b )N 掺杂K 2T i 6O 13的分态密度;(c )部分放大的N 掺杂K 2T i 6O 13的分态密度88 曲阜师范大学学报(自然科学版) 2023年Copyright ©博看网. All Rights Reserved.2.3 光学性质由于K 2T i 6O 13带隙的计算值比实验值偏小,为了使计算结果与实验结果相近,本文使用剪刀算符对光学性质的计算结果进行了修正,修正值取K 2T i 6O 13带隙的实验值与计算值的差值0.616e V.图4为N 掺杂前后K 2T i 6O 13介电函数虚部随光子能量变化曲线图.由图4可知在高能处,N 掺杂前后K 2T i 6O 13都有一个较大的峰值,这源于价带中的电子到导带的跃迁.在低能方向K 2T i 6O 13的介电函数虚部值基本为零,而N 掺杂后K 2T i 6O 13在低能范围出现了几个峰值,这源于其杂质能级中电子的跃迁.图4 K 2T i 6O 13和N 掺杂K 2T i 6O 13的介电函数虚部随光子能量变化曲线图由图5可知,K 2T i 6O 13对光的吸收范围约在0~400n m ,这个结果与已有的实验研究结果相近[20,21],再次证明我们的计算是合理的.N 掺杂后K 2T i 6O 13吸收边略有红移,这是由于其带隙值略微减小.N 掺杂后K 2T i 6O 13在350~400n m 的吸收强度明显增加,且实现了其对可见光的吸收,这是因为带隙中的杂质能级既可降低电子跃迁所需能量,又可提高光生载流子的效率.图5 K 2T i 6O 13和N 掺杂K 2T i 6O 13的吸收光谱3 结论通过第一性原理计算了K 2T i 6O 13在N 掺杂前后的能带结构㊁态密度㊁介电函数虚部和吸收光谱.计算结果表明,K 2T i 6O 13在N 掺杂后带隙变小,并且在能带中出现了杂质能级从而实现了N 掺杂后的K 2T i 6O 13对可见光的吸收.能带中的杂质能级可以抑制光生载流子的复合,使得光催化反应的效率提高.我们的计算结果为实验上研究K 2T i 6O 13光催化性能改性提供了重要的理论依据.参考文献:[1]H EY R ,Y A N FF ,Y U H Q ,e t a l .H y d r o ge n p r o d u c -t i o n i na l i g h t -d r i v e n p h o t o e l e c t r o c h e m i c a l c e l l [J ].A p pl E n e r g,2014,113:164.[2]O S T E R L OH F E .I n o r g a n i c m a t e r i a l sa sc a t a l ys t s f o r p h o t o c h e m i c a ls p l i t t i n g of w a t e r [J ].C h e m M a t e r ,2008,20:35.[3]R A NJ ,Z HA N GJ ,Y UJ ,e t a l .E a r t h -a b u n d a n t c o c a t a -l y s t s f o r s e m i c o n d u c t o r -b a s e d p h o t o c a t a l y t i cw a t e r s pl i t -t i n g [J ].C h e mS o cR e v ,2014,43:7787.[4]HA K U T A Y ,HA Y A S H IH ,A R A IKJ .H yd r o t he r m a l s y n t h e s i s of p h o t o c a t a l y s t p o t a s s i u m h e x a t i t a n a t e n a n o w i r e su n d e r s u pe r c r i t i c a l c o n d i t i o n s [J ].M a t e rS c i ,2004,39:4977.[5]K A P U S U ZD ,K A L A Y Y E ,P A R KJ ,e ta l .S yn t h e s i s a n d c h a r a c t e r i z a t i o no f h y d r o t h e r m a l l ygr o w n p o t a s s i u m t i t a n a t en a n o w i r e s [J ].JC e r a m P r o c e s sR e s ,2015,16:291.[6]L IY ,Y U H ,Y A N G Y ,e ta l .S yn t h e s i so f p o t a s s i u m h e x a t i t a n a t ew h i s k e r sw i t hh i g ht h e r m a l s t a b i l i t y f r o m T i -b e a r i n g e l e c t r i ca r cf u r n a c e m o l t e ns l a g [J ].C e r a m I n t ,2016,42:11294.[7]L IGL ,WA N G G H ,HO N GJ M.S yn t h e s i sa n dc h a r -a c t e r i z a t i o no fK 2T i 6O 13w h i s k e r sw i t h d i a m e t e r o n n a n -o m e t e r s c a l e [J ].JM a t e r S c i ,1999,18(22):1865-1867.[8]R AM íR Z -S A L G A D OJ ,D J U R A D OE ,F A B R YPJ .E u rS y n t h e s i s o f s o d i u m t i t a n a t e c o m p o s i t e s b y s o l -ge l m e t h o df o r u s e i ng a s p o t e n t i o m e t r i c s e n s o r s [J ].C e r a m S o c ,2004,24:2477.[9]P E S C A T O R IM ,Q U O N D AM C A R L O C .S yn t h e s i s a n d c h a r a c t e r i z a t i o no fK 2T i 6O 13na n o w i r e s [J ].C h e m P h y s L e t t ,2003,376:726.[10]MOH D A S ,V I S HA LSC ,AM E E R A.C o m pa r a t i v e s t u d y o f p o t a s s i u m h e x a t i t a n a t e (K 2T i 6O 13)w h i s k e r s p r e p a r e db y s o l -ge l a n ds o l i ds t a t e r e a c t i o nr o u t e s [J ].98第4期刘保通,等:N 掺杂K 2T i 6O 13电子结构和光学性质的第一性原理计算Copyright ©博看网. 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All Rights Reserved.。

纳米金功能水凝胶的制备及其催化还原活性研究

第37卷第4期2023年8月南华大学学报(自然科学版)Journal of University of South China(Science and Technology)Vol.37No.4Aug.2023收稿日期:2023-02-16基金项目:国家自然科学基金项目(21807058);湖南省教育厅重点基金项目(21A0279);南华大学博士启动基金项目(2014XQD32)作者简介:王晓娟(1978 ),女,副教授,博士,主要从事多功能凝胶的制备及性能方面的研究㊂E-mail:1052961032@DOI :10.19431/ki.1673-0062.2023.04.009纳米金功能水凝胶的制备及其催化还原活性研究王晓娟,张㊀浪,魏传晚,林英武(南华大学化学化工学院,湖南衡阳421001)摘㊀要:设计并合成了一种酪氨酸衍生物,既可以作为凝胶因子,又可以充当还原剂㊂在四氯金酸存在下,酪氨酸衍生物可以在室温下组装形成金属水凝胶,并且在凝胶中原位形成金纳米粒子㊂该凝胶的形成条件温和,只需要简单的超声处理,不需要额外加入其他还原剂和稳定剂㊂通过X 射线光电子能谱㊁X 射线衍射㊁透射电子显微镜㊁流变等测试方法,对形成的凝胶进行了表征,实验结果证实金纳米粒子均匀地分布在凝胶体系中㊂在硼氢化钠存在下,金属水凝胶对甲基橙具有优越的催化还原反应活性㊂通过准一阶动力学拟合,发现其速率常数值(0.2ʃ0.1)s -1高于文献中报道的大多数催化剂㊂关键词:甲基橙;金属水凝胶;金纳米粒子;染料催化中图分类号:O69文献标志码:A文章编号:1673-0062(2023)04-0067-07Synthesis and Catalytic Reduction Activity of Functional HydrogelContaining Au nanoparticlesWANG Xiaojuan ,ZHANG Lang ,WEI Chuanwan ,LIN Yingwu(School of Chemistry and Chemical Engineering,University of South China,Hengyang,Hunan 421001,China)Abstract :In this study,a tyrosine derivative compound was designed and synthesized,which can be used as both a gelator and a reductant.This compound and tetrachloroauric acid can assemble to form a metallohydrogel containing gold nanoparticles formed in situ under room temperature.The formation of this gel is under mild conditions and only re-quires simple ultrasonic treatment without the addition of other reducing agents and stabi-lizers.By charaterizations using X-ray photoelectron spectroscopy,X-ray diffraction,76第37卷第4期南华大学学报(自然科学版)2023年8月transmission electron microscopy and rheology analysis,the results showed that the goldnanoparticles were evenly distributed in gel.The experimental results confirmed that goldnanoparticles were evenly distributed in the gel system.In the presence of sodium boro-hydride,the metallohydrogel has excellent catalytic reduction activity for methyl orange.Through quasi-first-order kinetic fitting,it was found that the rate constant value(0.2ʃ0.1)s-1is higher than that of most catalysts reported in the literature.key words:methyl orange;metallohydrogel;gold nanoparticles;dyes catalyze0㊀引㊀言偶氮染料甲基橙(methyl orange,MO)等被广泛应用于纺织㊁工业㊁塑料等领域[1]㊂由于染料具有易吸附和反射阳光的特点,会阻碍光合作用,干扰物种在自然环境中的发育,因此他们排放到环境中之前,必须将之去除㊂但由于甲基橙相对稳定,可溶于水,且其生物降解性较低,通过普通的水净化或水处理方法等很难将其从水溶液中去除,因此,寻找简单的解决方案来处理这些污染物,以防止在环境中积累,已经引起了研究人员的极大兴趣㊂去除废水中有机污染物的常见方法有选择性吸附[2]㊁光催化[3]和电化学降解[4]等㊂然而,这些方法存在去除不完全㊁成本高㊁耗时长㊁能量输入连续等缺点,难以在实践中广泛应用㊂相较而言,催化还原不仅具有染料快速降解的优点,而且可以克服特殊光源辐射和能耗的限制㊂许多纳米材料,特别是金属纳米粒子(nanoparticles,NPs),已被应用于催化有毒染料的还原,具有快速㊁高效和经济的特性[5]㊂在报道的大量金属纳米粒子中,金纳米粒子(gold nanoparticles,Au NPs)因其优异的电子转移能力和良好的染料降解催化性能而深受广泛关注㊂然而,Au NPs与其他纳米颗粒一样不稳定,容易聚集㊂由于存在高表能和各种非共价相互作用,使得表面积减小,大大降低了其催化性能[6]㊂金属纳米粒子的表面积和尺寸是影响其催化能力的重要因素,因此,迫切需要提高金属纳米粒子的稳定性,防止其聚集,其中最常见的方法之一是引入各种稳定剂,包括表面活性剂㊁离子液体㊁聚合物等[7]㊂但这些方法得到的材料由于工艺复杂或催化活性较低,染料降解效率仍然不够高㊂超分子水凝胶是由大量的水分子和三维网络结构组成,由于其特殊的三维网络结构,水凝胶可以作为模板,均匀分散嵌入的纳米粒子,避免其聚集[8]㊂M.K.Dixit等在金属水凝胶中制备了具有催化活性的金纳米粒子[9]㊂Y.M.Mohan等人在预制的水凝胶中制备了银纳米粒子[10]㊂综上所述,大多数报道的金属纳米粒子都是在特殊条件下制备的,包括光照㊁额外的还原剂㊁聚合物介质或预制的凝胶体系等㊂因此,利用简单的方法获得均匀分散㊁催化性能优良的Au NPs依然具有很大的挑战性㊂本研究的主要目的是利用简单㊁环保的方法,构建一种高效含Au NPs并用于催化还原降解偶氮染料,设计并合成了一种基于酪氨酸衍生物的简单凝胶因子(2-QY),考虑到酪氨酸是少数具有还原性的氨基酸之一,得到的2-QY仍然具有这一特征㊂因此,在没有任何还原试剂的情况下, Au NPs可以原位形成㊂凝胶网络结构的形成使Au NPs可以均匀的分散在金属水凝胶(2-QY-Au NPs)中㊂研究表明,2-QY-Au NPs金属水凝胶对甲基橙的还原反应具有良好的催化活性㊂1㊀实验1.1㊀仪器和试剂本工作用到的仪器主要有四极杆电感耦合式等离子体质谱仪㊁快速停留光谱仪(stopped-flow)㊁紫外-可视分光光度计㊁透射电镜(trans-mission electron microscope,TEM)㊁X射线衍射仪(X-ray diffraction,XRD)㊁流变仪㊁核磁共振波谱仪㊂试剂主要包括L-酪氨酸和喹啉-2-甲醛㊁四氯金酸溶液(HAuCl4)㊁硼氢化钠(NaBH4)和甲基橙,以上试剂购自Aladin试剂公司(上海,中国),均未经进一步纯化使用㊂其他试剂包括盐酸㊁氢氧化钾㊁无水乙醇等,均为分析级试剂㊂1.2㊀2-QY的合成首先,用电子天平称取酪氨酸(0.92g)和氢86第37卷第4期王晓娟等:纳米金功能水凝胶的制备及其催化还原活性研究2023年8月氧化钾(0.28g),加入圆底烧瓶中,用20mL 去离子水溶解;然后将0.786g 喹啉-2-甲醛的乙醇溶液加入圆底烧瓶中㊂在50ħ下搅拌反应4h 后进行冰浴,接着加入0.23g 硼氢化钠,2h 后撤去冰浴继续反应1h㊂最后,用6mol /L 的盐酸进行中和,调整溶液的pH 约为7㊂所得的淡黄色粗产物用乙醇和水洗涤,干燥后得到的淡黄色固体产物命名为2-QY㊂1.3㊀2-QY-Au NPs 金属水凝胶的制备将2-QY 溶液(0.03mol /L)的pH 值调整至10.3,然后以物质的量之比为1ʒ1的比例加入HAuCl 4溶液,经超声处理20min 后,静置约5h 后变成紫色的2-QY-Au NPs 金属水凝胶㊂1.4㊀催化还原甲基橙首先分别配制20mL 100μmol /L MO 和10mmol /L NaBH 4,然后将配制好的MO 5mL㊁2-QY-Au NPs(0.04μmol /L)湿凝胶和NaBH 4分别加入到两个10mL 注射器中,在Stopped-flow (停留光谱仪)上记录在2-QY-Au NPs 金属水凝胶存在下,硼氢化钠还原甲基橙的紫外-可见光谱变化㊂反应过程中由于两个注射器溶液等量混合,MO 的终浓度为50μmol /L,NaBH 4的终浓度为5mmol /L,催化剂浓度由式(1)确定[11]㊂表观速率常数(k app )由式(2)确定[12]㊂[Au]NP =[HAuCl 4]N agg =2V m [HAuCl 4]N A 4πR 3(1)lnC t C 0=ln At A 0=-k app t (2)2㊀结果与讨论2.1㊀2-QY 的制备与表征本配合物2-QY 采用席夫碱还原法得到,合成路线见图1㊂2-QY 是一种淡黄色粉末,不溶于水,可溶于碱性水溶液㊂质谱结果如图2(a)所示为322.1Da (计算值);负离子模式测得值:321.1Da㊂2-QY 的1H-NMR 谱如图2(b)所示:δ8.18(d,J =8.5Hz,1H),7.82(d,J =9.0Hz,2H),7.67(t,J =7.5Hz,1H),7.49(t,J =7.5Hz,1H),7.29(d,J =8.5Hz,1H),6.81(d,J =8.5Hz,2H),6.41(d,J =8.5Hz,2H),3.89(dd,J =96,14.0Hz,2H),3.18(t,J =6.5Hz,1H),2.65(ddd,2H),1.04(t,J =7.0Hz,1H)㊂通过质谱和核磁结果证明得到2-QY 目标产物㊂图1㊀化合物2-QY 的合成路线Fig.1㊀Synthesis route of compound2-QY图2㊀2-QY (C 19H 18N 2O 3)的质谱和核磁结果Fig.2㊀EI-MS and 1H-NMR spectra of2-QY (C 19H 18N 2O 3)2.2㊀2-QY-Au NPs 金属水凝胶的制备和表征2-QY 不能自组装形成凝胶,而在pH =10.3时,有HAuCl 4的存在下,它们可以共组装形成2-QY-Au NPs 深紫色金属水凝胶,如图3㊂该凝胶的制备条件温和,只需要在室温下进行简单的超声处理㊂由于2-QY 中的酪氨酸部分依然具有还原能力,所以Au NPs 可以在凝胶中原位形成,无需加入额外的还原剂㊂图3㊀2-QY-Au NPs 金属水凝胶的形成Fig.3㊀Formation of 2-QY-Au NPs metallohydrogel96第37卷第4期南华大学学报(自然科学版)2023年8月从动力学频率扫描(dynamic frequencysweep,DFS)实验结果中可以看出,在整个测试过程中,能量储能模量(Gᶄ)始终大于损耗模量(Gᵡ),进一步证明了稳定的凝胶相的形成(见图4)㊂图4㊀2-QY-Au NPs 金属水凝胶的频率扫描图Fig.4㊀Dynamic frequency scan of 2-QY-Au NPsmetallohydrogel凝胶呈现深紫色表明了凝胶体系中Au NPs 的形成,这将通过不同的测试方法进一步证明㊂通过TEM,获得了2-QY-Au 干凝胶的微观结构㊂如图5(a)所示,2-QY-Au 干凝胶呈现出有序纳米片结构,从图5(b)可以看出Au NPs 均匀分散在纳米片中㊂图6(a)中526nm 左右的等离子体共振峰值进一步表明Au NPs 的形成㊂图5㊀2-QY-Au NPs 干凝胶的TEM 图像Fig.5㊀TEM images of 2-QY-Au NPs xerogel通过粉末X-射线衍射分析证明2-QY-Au NPs 凝胶的结构㊁非共价键作用力及Au NPs 的形成㊂由图6(b)可见,在20ʎ处有明显的宽峰,表明2-QY-Au NPs 金属水凝胶具有多孔结构;在0.23nm 和0.33nm 处的衍射峰表明凝胶体系中存在氢键和π-π堆积作用;此外,在38.2ʎ(111)㊁44.4ʎ(200)㊁64.6ʎ(220)和77.1ʎ(311)处的尖锐衍射峰被归因于Au NPs(JCPD No.04-078)[13]㊂X 射线光电子能谱(X-ray photoelectron spectroscopy,XPS)方法进一步证实了2-QY-Au 凝胶中的Au 的价态㊂如图6(c )所示,在87.3eV 和83.6eV 处出现两个信号峰,分别对应Au 4f 5/2和Au 4f 7/2的分裂能,证实Au(0)的存在㊂图6㊀2-QY-Au NPs 的紫外㊁XRD 和XPS 图谱Fig.6㊀UV ㊁XRD and XPS spectra of 2-QY-Au NPs7第37卷第4期王晓娟等:纳米金功能水凝胶的制备及其催化还原活性研究2023年8月2.3㊀2-QY-Au NPs 金属水凝胶催化还原甲基橙如图7(a)所示,MO 溶液中仅有NaBH 4存在时,使用紫外光谱监测,经过30min,MO 的特征吸收峰无明显变化,表示反应基本不进行㊂当在MO 和NaBH 4的混合溶液中加入2-QY-Au NPs 金属水凝胶作为催化剂时,只需15s,MO 在464nm 处的特征峰基本降解完全,同时溶液由橙黄色变为无色㊂通过Stopped-flow 监测反应的动力学情况(如图7(b)),同时通过准一级动力学拟合确定MO 的k app 为(0.20ʃ0.1))s -1(如图7(c))㊂本研究中的k app 比报道的大多数k app 都大(见表1),表明2-QY-Au NPs 金属水凝胶对MO 的还原降解具有良好的催化活性㊂甲基橙属于较为常见的偶氮化合物类染料,在无催化剂的情况下,染料降解过程中反应体系的电子无法很好地转移,本工作中,Au NPs 可以作为电子转移载体,使反应速率加快,还原机理为通过电子转移还原氮氮双键,使甲基橙褪为无色,利用质谱分析降解产物证明了氮氮双键的断裂㊂产物分别为对氨基苯磺酸(m /z =172),结构和质谱结果如图8(a);N,N-二甲基对苯二胺(m /z =137),结构和质谱结果如图8(b)㊂表1㊀不同催化剂催化MO 降解速率比较Table 1㊀Comparison of k app for MO degradationunder different catalysts 金属纳米粒子速率常数k app /s -1参考文献Au@TiO 23.88ˑ10-3[14]Au-Ag BNPs 9.24ˑ10-3[15]Fe 3Pt-AgNPs 3.83ˑ10-3[16]CuNPs0.032[17]AuNPs0.2031本工作图7㊀MO 降解动力学分析Fig.7㊀Kinetic analysis of MO degradation17第37卷第4期南华大学学报(自然科学版)2023年8月图8㊀甲基橙降解产物结构和质谱图Fig.8㊀Structure and mass spectrum of MO degradation products3㊀结㊀论本研究采用一种希夫碱㊁还原法合成了2-QY氨基酸衍生物,并进行简单地处理,形成了2-QY-Au NPs金属水凝胶㊂通过XRD㊁XPS㊁TEM等检测方法发现原位形成的金纳米粒子在凝胶体系中分布均匀㊂通过实验证明2-QY-Au NPs金属水凝胶对MO的还原具有良好的催化效果㊂利用光谱动力学监测,通过准一阶动力学拟合,发现其速率常数为(0.2ʃ0.1)s-1,优于文献中报道的许多纳米材料㊂参考文献:[1]LI X J,WANG Z M,NING J L,et al.Preparation and characterization of a novel polyethyleneimine cation-mod-ified persimmon tannin bioadsorbent for anionic dye ad-sorption[J].Journal of environmental management,2018, 217:305-314.[2]杜顺利,郭耸,耿宇豪,等.羟基硝酸锌对甲基橙的吸附性能研究[J].化学研究与应用,2022,34(8): 1711-1718.[3]张寿涛,郭贵宝.炭吸附共沉淀法制EuFeO3纳米粉体及其光催化性能研究[J].现代化工,2022,42 (11):141-144.[4]金秋,刘世桐,郑雪婷.隔膜体系阴阳极共同作用与电化学法降解水中的甲基橙[J].建筑与预算,2020 (7):64-67.[5]BEMHARDT S,DURING J,HASCHKE S,et al.Tunable photocatalytic activity of PEO-Stabilized ZnO-polyoxo-metalate nanostructures in aqueous solution[J].Advanced materials interfaces,2021,8(14):2002130. 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[12]SAKIR M,ONSES M S.Solid substrates decorated withAg nanostructures for the catalytic degradation of methylorange[J].Results in physics,2019,12:1133-1141.[13]WANG L Q,JIANG X X,ZHANG M,et al.In situ as-sembly of Au nanoclusters within protein hydrogel net-works[J].Chemistry-an Asian journal,2017,12(18):2374-2378.[14]KHAN M M,LEE J,CHO M H.Au@TiO2nanocompos-ites for the catalytic degradation of methyl orange andmethylene blue:An electron relay effect[J].Journal ofindustrial and engineering chemistry,2014,20(4): 1584-1590.[15]AKILANDAEASWARI B,MUTHU K.One-pot green syn-thesis of Au-Ag bimetallic nanoparticles from Lawsoniainermis seed extract and its catalytic reduction of envi-ronmental polluted methyl orange and4-nitrophenol[J].Journal of the Taiwan institute of chemical engi-neers,2021,127:292-301.[16]HAN D L,LI B X,XING G L,et al.Facile synthesis ofFe3Pt-Ag nanocomposites for catalytic reduction ofmethyl orange[J].Chemical research in Chinese uni-versities,2018,34(6):871-876.[17]SOOMRO R A,NAFADY A.Catalytic reductive degra-dation of methyl orange using air resilient copper nano-structures[J].Journal of nanomaterials,2015,16(1):120.37。

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Synthesis and Characterization of Transparent LuminescentZnS:Mn/PMMA NanocompositesH.Althues,†R.Palkovits,‡A.Rumplecker,‡P.Simon,§W.Sigle,|M.Bredol,⊥U.Kynast,⊥and S.Kaskel*,†Inorganic Chemistry Department,Technical Uni V ersity of Dresden,Mommsenstrasse6, D-01069Dresden,Germany,Max-Planck-Institute of Coal Research,Kaiser-Wilhelm-Platz1,D-45470Mu¨lheim a.d.Ruhr,Germany,Max-Planck-Institute for Chemical Physics of Solids,No¨thnitzer Strasse40,D-01187Dresden,Germany,Max-Planck-Institut for Metals Research,Heisenbergstrasse3, D-70569Stuttgart,Germany,and Uni V ersity of Applied Sciences Mu¨nster,Stegerwaldstrasse39,D-48565Steinfurt,GermanyRecei V ed December23,2004.Re V ised Manuscript Recei V ed October3,2005Transparent luminescent nanocomposites were obtained using the bulk polymerization of transparent dispersions containing manganese-doped ZnS nanoparticles with a crystallite size of2nm in a mixture of methyl methacrylate and acrylic acid.The effective diameter in the monomer dispersions is22nm as determined using dynamic light scattering and depends on the composition of the continuous phase but is significantly higher than the primary crystallite size of the ZnS:Mn nanoparticles initially obtained from the precipitation reaction.The dispersions are stable up to8months.Deprotonated carboxylate groups are detected in IR spectra(1547,1437cm-1)of particles isolated from a stable dispersion indicating the presence of surface-bound acrylate molecules.Thermal bulk polymerization of the entire dispersions is suitable for production of luminescent acrylic glasses with an emission maximum at590nm(330nm excitation)and a quantum yield of29.8%.Ultramicrotome cuts of the nanocomposites with a thickness of50-100nm were prepared for transmission electron microscopic investigations.In the micrographs, a low degree of agglomeration is observed and the agglomerate diameter is below20nm.In the nanocomposites,light scattering and turbidity is minimized due to the small particle size and high degree of dispersion,resulting in highly transparent acrylic glasses with a transmittance as high as87%(600 nm).IntroductionThe incorporation of inorganic particles into polymers allows one to integrate new functions inside polymer matrixes.1-7For transparent plastics,modification of the matrix by dispersing a second inorganic component into the polymer typically results in a significant loss of transparency due to scattering from large particles or agglomerates.A novel approach for the functionalization of transparent plastics is the use of nanoparticles.8Since the Rayleigh scattering intensity is proportional to d6(d)particle diameter),the integration of small particles(d<30nm)can be applied to transparent plastics without dramatic loss of transparency.However,a challenge is to avoid agglomeration inside the matrix,resulting in turbid composites,and thus techniques need to be developed that allow for the integration of particles with a high external surface area into polymers. In the following,we describe the integration of manganese-doped ZnS nanoparticles(ZnS:Mn)into transparent PMMA (poly(methyl methacrylate))plastics using an in situ polym-erization approach.In the first step,stable ZnS:Mn nano-particle dispersions are generated in which the monomer forms the continuous phase.In the second step,the continu-ous phase is polymerized by radical polymerization in substance;i.e.,the entire continuous phase is transformed into a solid polymer block(Scheme1).Manganese-doped ZnS nanoparticles have been studied by several groups in recent years and synthesis procedures are well-established.9-16For Cd(Hg)S(Se,Te)nanoparticles,*To whom correspondence should be addressed.E-mail:Stefan.Kaskel@ chemie.tu-dresden.de.Phone:49-351-46333632.Fax:49-351-46337287.†Technical University of Dresden.‡Max-Planck-Institute of Coal Research.§Max-Planck-Institute for Chemical Physics of Solids.|Max-Planck-Institut for Metals Research.⊥University of Applied Sciences Mu¨nster.(1)Kickelbick,G.Prog.Polym.Sci.2003,28,83-114.(2)Beecroft,L.L.;Ober,C.K.Chem.Mater.1997,9,1302-1317.(3)Ash,B.J.;Schadler,L.S.;Siegel,R.W.Mater.Lett.2002,55,83-87.(4)Avella,M.;Errico,M.E.;Martuscelli,E.Nano Lett.2001,213-217.(5)Godovsky,D.Y.Ad V.Polym.Sci.2000,153,163-205.(6)Yeh,J.M.;Liou,S.J.;Lin,C.Y.;Cheng,C.Y.;Chang,Y.W.Chem.Mater.2002,14,154-161.(7)Popovic,I.G.;Katsikas,L.;Mu¨ller,U.;Velickovic,J.S.;Weller,H.Macromol.Chem.Phys.1994,195,889-904.(8)Ajayan,P.M.;Schadler,L.S.;Braun,P.V.Nanocomposite Scienceand Technology,1st ed.;Wiley-VCH:Weinheim,2003.(9)Balaz,P.;Valko,M.;Boldizarova,E.;Briancin,J.Mater.Lett.2002,57,188-191.(10)Gan,L.M.;Liu,B.;Chew,C.H.;Xu,S.J.;Chua,S.J.;Loy,G.L.;Xu,ngmuir1997,13,6427-6431.(11)Leeb,J.;Gebhardt,V.;Mu¨ller,G.;Haarer,D.;Su,D.;Giersig,M.;McMahon,G.;Spanhel,L.J.Phys.Chem.B1999,103,7839-7845.(12)Vacassy,R.;Scholz,S.M.;Dutta,J.;Plummer,C.J.G.;Houriet,R.;Hofmann,H.J.Am.Ceram.Soc.1998,81,2699-2705.(13)Xu,S.J.;Chua,S.J.;Liu,B.;Gan,L.M.;Chew,C.H.;Xu,G.Q.Appl.Phys.Lett.1998,73,478-480.(14)Konishi,M.;Isobe,T.;Senna,M.J.Lumin.2001,93,1-8.1068Chem.Mater.2006,18,1068-107210.1021/cm0477422CCC:$33.50©2006American Chemical SocietyPublished on Web02/01/2006efficient phase transfer into nonpolar solvents is observed after particle capping using thiols or polymer ligands.17-19CdSe-based polymer composites were obtained using tri-n -octylphosphine oxide 20or via phase transfer using octadecyl-p -vinyl-benzyldimethylammonium chloride.21However,cad-mium-and mercury-containing additives and phosphine oxides are problematic in industrial polymer processing because they are highly toxic and expensive.To our knowledge,so far the integration of luminescent ZnS nanoparticles into polymer matrixes was only studied for the manufacture of thin films for electroluminescent devices.15,22,23ZnS -polymer nanocomposite films with high refractive index were prepared by incorporating thiophenol-capped ZnS nanoparticles into urethane-based polymers.24CdS -ZnS core -shell particles well-dispersed in polycetyl-p -vinylbenzyldimethylammonium chloride were obtained using the reverse micelle method.25In thin nanocomposite films (a <50µm),the small thickness of the film is the reason for the high transmittance.However,in macroscopic acrylate-based glasses (a >5mm)agglomeration of the particles may lead to a severe loss of the transmittance.Thus,for the development of highly transparent bulk nanocomposites,not only a small particle diameter and narrow particle size distribution are essential but also the key is to develop preparation methods avoiding agglomeration of the particles inside the polymer matrix.The secondary agglomerate structures,present in dried nanopar-ticle powders,are rarely broken up by direct mixing with polymers in the melt (compounding)or in solution due to the strong interfacial forces and the high specific surface area of inorganic nanoparticles.However,a stable dispersion of the nanoparticles in the monomer can be converted into a transparent nanocomposite if the formation of the polymer in the vicinity of the particles does not induce agglomeration.In the following,we describe the manufacture of such macroscopic PMMA blocks containing well-separated man-ganese-doped ZnS nanoparticles (ZnS:Mn)with orange photoluminescence.Experimental SectionZinc acetate dihydrate (Fluka,5.00g,22.8mmol)and manganese acetate tetrahydrate (Fluka,0.12g,0.49mmol)were dissolved in 150mL of methanol.Na 2S (Acros,61%,3.00g,23.3mmol)dissolved in a mixture of 40mL of water and 40mL of methanol was added and the resulting suspension was stirred for 15min.The white precipitate was separated by centrifugation (4000rpm,10min)and dispersed in acrylic acid (10g in 30mL of acrylic acid).Heat treatment at 363K in air gave a transparent dispersion that was further stabilized by the addition of zinc acetate.Subsequently,the dispersion was diluted with methyl methacrylate (MMA,200%w/w)and polymerized at 318K after the addition of AIBN (Acros,0.2%w/w)for 12h.Hardening was carried out at 363K to give a transparent nanocomposite with a ZnS:Mn content of 1.1%w/w.The transmittance of 5mm thick PMMA blocks was measured using a UV/Vis-Spectrometer 1650PC (Shimadzu).Luminescence quantum yields of a 2mm thick nanocomposite plate and of ZnS:Mn powder isolated from the dispersion in acrylic acid were determined using a 450W Xe lamp,Acton excitation and emission monochromators of 300mm focal length and gratings with 1200g/mm,and an Acton photomultiplier tube P2.Emission spectra were integrated between 500and 700nm using an excitation wavelength of 331nm.Both nanocomposite and powdered sample were evaluated vs LumogenRot F 300(150ppm in PMMA,1.6mm disk and powdered),with a quantum yield of 42%over the spectral range in question (BASF).LumogenRot F 300references were generously provided by BASF,Ludwigshafen.For transmission electron microscopic investigations,one drop of the ZnS:Mn/AA suspension was placed on a carbon film coated copper grid.After drying,the ZnS:Mn sample was washed with ethanol several times.Transmission electron micrographs were obtained using a Philips CM200FEG\ST Lorentz electron micro-scope with a field emission gun at an acceleration voltage of 200kV.For further electron microscopic studies the composite material was cut into thin slices by means of an ultramicrotome (element six)(thickness of the sections <100nm).The slices were supported on holey carbon film covered copper grids.High-angle annular dark-field images (HAADF)were obtained in a VG HB501UX dedicated scanning transmission electron microscope equipped with a cold field-emission gun and operated at 100kV.HAADF images show bright contrast in areas containing atoms of high atomic number,such as Zn,whereas the light composite matrix (consisting mainly of carbon)shows dark contrast.Therefore,this imaging technique is often referred to as Z-contrast.For the dynamic light scattering measurements,a Brookhaven instrument (90Plus)was used at 296K.The viscosity of the MMA-diluted dispersion was 1.13cP whereas for the acrylic acid dispersion the viscosity of pure acrylic acid was used for the(15)Kezuka,T.;Konishi,M.;Isobe,T.;Senna,M.J.Lumin.2000,87-9,418-420.(16)Igarashi,T.;Isobe,T.;Senna,M.Phys.Re V .B 1997,56,6444-6445.(17)Gaponik,N.;Talapin,D.V.;Rogach,A.L.;Eychmu ¨ller,A.;Weller,H.Nano Lett.2002,2,803-806.(18)Potapova,I.;Mruk,R.;Prehl,S.;Zentel,R.;Basche,T.;Mews,A.J.Am.Chem.Soc.2003,125,320-321.(19)Koktysh,D.S.;Gaponik,N.;Reufer,M.;Crewett,J.;Scherf,U.;Eychmu ¨ller,A.;Lupton,J.M.;Rogach,A.L.;Feldmann,J.Chem.Phys.Chem.2004,5,1435-1438.(20)Lee,J.;Sundar,V.C.;Heine,J.R.;Bawendi,M.G.;Jensen,K.F.Ad V .Mater.2000,12,1102-1105.(21)Zhang,H.;Cui,Z.C.;Wang,Y.;Zhang,K.;Ji,X.L.;Lu,C.L.;Yang,B.;Gao,M.Y.Ad V .Mater.2003,15,777-780.(22)Yang,Y.;Huang,J.M.;Liu,S.Y.;Shen,J.C.J.Mater.Chem.1997,7,131-133.(23)Yang,Y.;Xue,S.H.;Liu,S.Y.;Huang,J.M.;Shen,J.C.Appl.Phys.Lett.1996,69,377-379.(24)Lu ¨,C.;Cui,Z.;Wang,Y.;Li,Z.;Guan,C.;Yang,B.;Shen,J.J.Mater.Chem.2003,13,2189-2195.(25)Lu,S.-Y.;Wu,M.-L.;Chen,H.-L.J.Appl.Phys.2003,93,5789-5793.Scheme 1.In Situ Polymerization Method for the Generation of Transparent ZnS:Mn/PMMANanocompositesTransparent Luminescent ZnS:Mn/PMMA Nanocomposites Chem.Mater.,Vol.18,No.4,20061069determination of the effective diameter (1.15cP).All dispersions were filtered using a 0.2µm PTFE-membrane filter before the measurement.1H NMR spectra of samples in D 2O were recorded using a Bruker instrument (DPX 300)at 300MHz and 300K.A Nicolet instrument (Magna IR 750)was used for Fourier Transform Infrared Spectra measurements in KBr tablets in the range 4000-400cm -1.Results and DiscussionManganese-doped ZnS nanoparticles were obtained from the reaction of Na 2S,zinc acetate and manganese acetate in methanol and isolated via centrifugation.16A dependence of the crystallite size with respect to the initial Zn 2+/S 2-ratio used in the precipitation is evident from the broad Bragg reflections caused by size broadening (Figure 1).The smallest crystallites with a mean diameter of 1.3nm (line-broadening analysis using the Scherrer equation)are obtained with a high Zn 2+excess (molar Zn 2+/S 2-ratio )4.0,Figure 1,pattern a),whereas at a ratio of 1.0the crystallite size is 2.0nm (Figure 1,pattern d).The concentration of manganese ions does not influence the particle size as much.With the addition of 1at.%Mn 2+relative to Zn 2+during synthesis (molar Zn 2+/S 2-ratio )2.0),the resulting particle diameter is 1.6nm,while 10%Mn 2+leads to particles 1.9nm in diameter.According to Bol et al.,26the quantum efficiency of ZnS:Mn nanocrystals reaches a maximum for doping levels of 1.5-5.6%and is constant in this range.However,the optimum concentrations depend strongly on synthesis conditions.26In this work a doping concentration of 2.1at.%Mn 2+was chosen,leading to 1.0at.%incorporated Mn 2+ions,as determined by elemental analysis.Dispersion of Luminescent ZnS:Mn Nanoparticles in Acrylic Acid and MMA.The key step for the generation of transparent plastics is to transfer the particles into a stable dispersion of the monomer.ZnS cannot be directly dispersed in MMA without severe agglomeration,leading to an unstable dispersion.In our approach,the particles are first agitated in acrylic acid (AA)at higher temperature,leading to a stable,transparent dispersion of the nanosized particles.This concentrated dispersion can be diluted with organic solvents or other comonomers such as methyl methacrylate.The size of the particles in the AA/MMA dispersion (1:2)was determined using dynamic light scattering (Figure 2).Typically,a broad size distribution is obtained with a mean particle size of 22nm and a polydispersity index of 0.16.The tail toward larger diameters is caused by aggregates of primary particles.The stability of the dispersions was monitored for several hours using dynamic light scattering.Figure 3a shows the average particle size in the pure acrylic acid dispersion as a function of time.The effective diameter is 14nm and does not significantly change within several hours.In fact,the pure acrylic acid dispersion is stable over more than 8months!The acrylic acid dispersion can be diluted with up to 200%methyl methacrylate without loss of transparency.In the AA/MMA dispersion the effective particle diameter is 22nm and also constant for 8h (Figure 3b).In comparison to the crystallite size determined from size broadening using the Scherrer equation (above),the effective diameter determined from light scattering differs by a factor of 10.Transmission electron micrographs of ZnS:Mn nanoparticles,taken from the dispersion in acrylic acid,confirm the presence of single,isolated nanocrystals (Figure 4,inset).The overview image (Figure 4)shows layers of uniform particles,but does not allow for determination of the degree of aggregation.Within the limits of error of the different methods,the comparison indicates that crystallite and agglomerate size in the dispersion are not identical.Thus,the higher effective diameter observed by means of dynamic light scattering indicates a low degree of agglomeration,even in transparent dispersions.However,the small agglomerates in the dispersions are stable at room temperature for several months.(26)Bol,A.A.;Meijerink,A.J.Phys.Chem.B 2001,105,10197-10202.Figure 1.X-ray powder patterns of manganese-doped ZnS nanoparticles obtained by precipitation (molar Zn/S ratio: 4.0(a),2.0(b),1.3(c),and 1.0(d)).Figure 2.Intensity-weighed particle size distribution of manganese-doped ZnS particles in a monomer dispersion containing methyl methacrylate and acrylic acid (2:1).Inset:corresponding correlationfunction.Figure 3.Effective diameter of manganese-doped ZnS particles in dispersions of (a)acrylic acid,(b)methyl methacrylate and acrylic acid (2:1),and (c)acetone and acrylic acid (5:1).1070Chem.Mater.,Vol.18,No.4,2006Althues et al.In contrast,for a dispersion diluted with acetone,a steady increase of the effective diameter up to 130nm after 9h is observed (Figure 3c)that is not accompanied by crystal growth according to XRD powder patterns,demonstrating a delicate dependence of the dispersion stability on chemical composition.The stability of monomer dispersions and the possibility to dilute such dispersions with a second monomer such as MMA is crucial for the subsequent bulk polymeri-zation used in our approach to obtain acrylic glasses.To preclude the formation of poly(acrylic acid)during the heat treatment,which could also be responsible for the stability of the dispersion,we have analyzed the continuous phase using 1H NMR.However,in solution only the dimerization product was detected as a minor impurity.The particles were subsequently isolated from the acrylic acid dispersion by adding methanol and separating the solid precipitate.The precipitate was dissolved in a mixture of DCl and D 2O.In the resulting solution,only monomeric acrylic acid was detected,indicating that the small molecules are responsible for effective stabilization of the particles in the dispersion.In IR spectra of ZnS:Mn nanoparticles,isolated after the acrylic acid treatment,bands at 1547and 1437cm -1confirm the presence of deprotonated carboxyl groups that are coordinated to the surface of the ZnS particles (Figure 5).15Adsorbed acrylic acid molecules are known to increase the photoluminescence intensity of ZnS:Mn nano-crystals.15The stability of the dispersion is critically affected by several factors.In particular,small amounts of primary amines or water stabilize the dispersion;especially octyl-amine prevents aggregation when unpolar solvents such as MMA are added to the dispersion of particles in acrylic acid.The addition of zinc salts such as zinc acetate or zinc acrylate enhances the stability,while sodium acrylate or magnesium acetate do not stabilize the dispersion.Thus,adsorption of ions and subsequent electrostatic stabilization seems to be crucial for the stabilization.The latter is surprising since the zeta potential of inorganic particles in nonpolar solvents is typically very small.27Electrophoretic mobility measurements of the ZnS/AA-MMA dispersion were below detectability.Only if the acrylic acid dispersion is diluted with acetone,low mobilities (-1.02×10-8m 2/V ‚s)can be detected,corresponding to a zeta potential of -18mV.Thus,two factors are responsible for the stability of the ZnS/monomer dispersion:(1)coordination of acrylic acid modifies the surface of the particles and leads to a hydro-phobization;(2)the adsorption of ions leads to a surface charge and causes electrostatic repulsion.In Situ Polymerization and Nanocomposite Properties.Transparent composites are obtained by polymerization in the bulk.Bulk polymerization is industrially used for the production of acrylic glasses and PMMA with high molecular weight.As compared to other polymerization techniques in solvents,in our bulk polymerization approach the entire continuous phase is transformed into a solid block.The blocks are highly transparent.Even 10mm thick blocks do not appear turbid (Figure 6).To achieve this goal,the dispersion also has to be stable at the polymerization temperature for at least 8h until most of the monomer is converted.The glasses obtained are insoluble in organic solvents and show only a low degree of swelling in contact with solvents.A shrinkage of 17%compared to the volume of the liquid dispersion was observed for the nanocomposites after polymerization.Since the crystallite size of the luminophor is 1.3-2.0nm and the particles are only little agglomerated in the dispersion and in the composite (below),the transmittance of the(27)Morrison,I.D.Colloid Surf.A 1993,71,1-37.Figure 4.Transmission electron micrograph of ZnS:Mn nanoparticles isolated from dispersion in acrylic acid.Inset:High-resolution image of a singlenanocrystal.Figure 5.IR spectrum of manganese-doped ZnS nanoparticles isolated from an acrylic aciddispersion.Figure 6.Photograph of a transparent ZnS:Mn/PMMA nanocomposite block (10×10×10mm 3)obtained using in situ bulk polymerization.Transparent Luminescent ZnS:Mn/PMMA Nanocomposites Chem.Mater.,Vol.18,No.4,20061071composites is very high (Figure 7).Pure PMMA has a transmittance of 92%(Figure 7a).The loss of 8%is caused by reflection on the two surfaces of the block (5mm thickness).In our approach,significant amounts of acrylic acid are copolymerized with MMA.The transmittance of the pure copolymer blocks (MMA:AA )2:1)is somewhat lower than that of PMMA (89.1%,λ)600nm)(Figure 7b).The final ZnS/AA-MMA nanocomposite contains acrylic acid and small amounts of zinc rger particles would give rise to a significant reduction of the transmittance,whereas in the nanocomposite (Figure 7c)the transmittance is still as high as 87.3%(600nm).The high transmittance confirms the concept of our approach.The integration of nanoparticles allows for the incorporation of functional inorganic particles that are invisible by the human eye.Thus,novel functions can be realized that may not be achieved by modification of functional polymer branches alone.An advantage of in-organic phosphors is the high UV stability,whereas organic molecules are prone to bleaching.However,long-term stability tests are beyond the scope of this work.A representative scanning transmission electron micro-graph of the nanocomposite is shown in Figure 8(ultra-microtome cut,thickness <100nm).The particles are highly dispersed in the composites.Due to the small size of the crystallites (1.3-2nm)and the presence of the matrix,we were unable to obtain atomic resolution TEM data.In addition,at high electron dose rate,typically the organic ultramicrotome cut was not stable.In the scanning transmis-sion electron micrograph (Z-contrast),the particles appear as white inclusions slightly larger than the primary crystallite size determined from line broadening.A low degree of agglomeration is detected.Most of the agglomerates are below 5nm in diameter but also extended structures with a length up to 20nm are discerned.As compared to the effective diameter in the dispersion (22nm)determined using dynamic light scattering,the agglomerates observed by STEM in the composite are slightly smaller.However,a direct comparison of the results is problematic since size distributions from DLS are intensity-weighed whereas those from STEM are number-weighed.Additionally,the degree of agglomeration in the dispersion is not necessarily identical with that in the nanocomposite.Through all processing steps,the functionality of the ZnS:Mn nanoparticles is fully retained.The composites show the orange luminescence of the Mn-doped nanoparticles when irradiated with UV light (254nm).The emission spectrum (330nm excitation)of the composite (Figure 9)shows the same broad band as bulk ZnS:Mn centered at 590nm.15The emission band at 420nm can be attributed to trap emission of ZnS and fluorescence of acrylic acid.15For the determi-nation of quantum efficiencies the emission range of 500-700nm and an excitation wavelength of 331nm were used.A quantum efficiency of 29.8%was determined for the nanocomposite (2mm thick plate)while a higher value of 38%was measured for the isolated ZnS:Mn powder.The deviation between nanocomposite (transmission)and powder (reflectance)quantum yields of 8%is very reasonable,considering the very low reflectance of the reference Lu-mogenRot at 331nm.ConclusionWe have presented an efficient method for the generation of luminescent inorganic -organic hybrid materials.Whereas other methods for the synthesis of inorganic nanoparticles often make use of highly toxic and expensive stabilizing agents such as phosphine oxides,amines,thiols,and sur-factants,the method presented here is highly cost efficient and may be suitable for industrial production.Acknowledgment.This research project is funded by the “Young Scientist Nanotechnology Initiative”of the Federal Ministry of Education and Research (BMBF:FK 03X5502).CM0477422Figure 7.Transmission spectra of (a)pure PMMA,(b)PAA/PMMA copolymer,and (c)ZnS:Mn/PMMAnanocomposite.Figure 8.Scanning transmission electron micrograph of the ZnS:Mn/PMMA nanocomposite (ultramicrotomecut).Figure 9.Emission spectrum of the ZnS:Mn/PMMA nanocomposite (330nm excitation).1072Chem.Mater.,Vol.18,No.4,2006Althues et al.。