Synthesis and characterization of tantalum nitride nanopowder prepared through homogeneous reac

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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
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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.

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. References[1]H.Kisch,L.Zang, nge,W.F.Maier, C.Antonius, D.Meissner,Angew.Chem.,Int.Ed.37(1998)3034.[2]W.Macyk,H.Kisch,Chem.Eur.J.7(2001)1862;C.Wang,D.W.Bahnemann,J.K.Dohrmann,mun.16(2000)1539.[3]H.Yamashita,M.Honda,M.Harada,Y.Ichihashi,M.Anpo,T.Hirao,N.Itoh,N.Iwamoto,J.Phys.Chem.B102(1998) 10707.[4]T.Umebayashi,T.Yamaki,H.Itoh,K.Asai,Appl.Phys.Lett.81(3)(2002)454.[5]R.Asahi,T.Ohwaki,K.Aoki,Y.Taga,Science293(2001)269.[6]C.Burda,Y.Lou,X.Chen,A.C.S.Samia,J.Stout,J.L.Gole,Nano Lett.3(8)(2003)1049.[7]H.Irie,Y.Watanabe,K.Hashimoto,J.Phys.Chem.B107(2003)5483.[8]J.L.Gole,J.D.Stout,C.Burda,Y.Lou,X.Chen,J.Phys.Chem.B108(2004)1230.[9]T.Lindgren,J.M.Mwabora,E.Avendano,J.Jonsson,A.Hoel,C.Granqvist,S.Lindquist,J.Phys.Chem.B107(2003)5709.[10]W.Zhao,W.Ma,C.Chen,J.Zhao,Z.Shuai,J.Am.Chem.Soc.126(2004)4782.[11]H.Irie,Y.Watanabe,K.Hashimoto,Chem.Lett.32(8)(2003)772.[12]S.U.M.Khan,M.Al-shahry,W.B.Ingler Jr.,Science297(2002)2243.[13]M.Janus,B.Tryba,M.Inagaki,A.W.Morawski,Appl.Catal.B52(2004)61.[14]S.Sakthivel,H.Kisch,Angew.Chem.,Int.Ed.42(2003)4908.[15]X.Y.Du,Y.Wang,Y.Y.Mu,L.L.Gui,P.Wang,Y.Q.Tang,Chem.Mater.14(2002)3953.[16]Y.Z.Li,Y.N.Fan,H.P.Yang,B.L.Xu,L.Y.Feng,M.F.Yang,Y.Chen,Chem.Phys.Lett.372(2003)160.[17]L.Bonneviot,G.L.Haller,J.Catal.113(1988)96.[18]T.Huizinga,R.Prins,J.Phys.Chem.85(1981)2156.[19]S.A.Fairhurst, A.D.Inglis,Y.Le Page,J.R.Morton,K.F.Preston,Chem.Phys.Lett.95(1983)444.[20]E.Serwicka,Colloid.Surf.13(1985)287.[21]I.Nakamura,N.Negishi,S.Kutsuna,T.Ihara,S.Sugihara,K.Takeuchi,J.Mol.Catal.A161(2000)205.[22]D.C.Cronemeyer,Phys.Rev.113(1959)1222.Y.Li et al./Chemical Physics Letters404(2005)25–2929。

球状PbS纳米颗粒的室温合成与性能表征

收稿日期：２０１５－１２－３１；修订日期：２０１６－０４１３基金项目：国家自然科学基金（５１５０２０８１）；河南省基础与前沿技术研究计划项目（１２２３００４１３２０８）作者简介：王天兴（１９７３一），男，河南省人，博士，副教授。Ｅ－ｍａｉｌ：ｗｔｘｄｄ＠１６３．ＣＯｎｌ通讯作者：刘海瑞，博士，副教授。Ｅ—ｍａｉｌ：ｌｉｕｈａｉｒｕｉｌ＠１２６．ｃｏｒｎ
王天兴，陈四香，刘海瑞，
（１．河南师范大学物理与电子工程学院，新乡４５３００３；２．河南省光伏材料重点实验室，新乡４５３００３）
摘要：以醋酸铅为铅源，硫代乙酰胺为硫源，在表面活性剂十二烷基硫酸钠（ＳＤＳ）和十六烷基三甲基溴化铵
第４５卷第５期２０１６年５月
人工晶体学报
ＪＯＵＲＮＡＬＯＦＳＹＮＴＨＥＴＩＣＣＲＹＳＴＡＬＳ
Ｖｏ１．４５Ｎｏ．５Ｍａｖ．２０１６
球状ＰｂＳ纳米颗粒的室Ｉ曰ｒｍ△口成与性能表征
z z z PsgiolePfrp
（ＣＴＡＢ）共同作用下，在常温下合成了ＰｂＳ纳米晶，利用ＸＲＤ、紫外分光度计、ＳＥＭ、ＴＥＭ对合成产物的结构和形貌
以及光学特性进行了表征分析，结果表明，合成的ＰｂＳ为尺寸均匀的球形纳米晶，对合成的ＰｂＳ纳米晶的形成机理
进行了初探。当反应温度较低时，形成的ＰｂＳ小颗粒在表面活性剂ＳＤＳ的烷基链模板和ＣＴＡＢ微胶束软模板共同
ｃｈａｒａｃｔｅｒｉｚｅｄｂｙＸＲＤ，ｕｌｔｒａｖｉｏｌｅｔ—ｖｉｓｉｂｌｅｓｐｅｃｔｒｏｐｈｏｔｏｍｅｔｅｒ，ＳＥＭａｎｄＴＥＭ．Ｔｈｅｒｅｓｕｌｔｓｓｈｏｗｔｈｅａｓ— ｏｂｔａｉｎｅｄＰｂＳａｒｅｓｐｈｅｒｉｃａｌｓｔｒｕｃｔｕｒｅｗｉｔｈａｓｉｚｅｏｆ５０—７０ｎｍ．ＴｈｅｆｏｒｍａｔｉｏｎｍｅｃｈａｎｉｓｍｏｆｓｐｈｅｒｉｃａｌＰｂＳｎａｎｏｃｒｙｓｔａｌｓｗｅｒｅｄｉｓｃｕｓｓｅｄｔｈａｔｔｈｅｓｐｈｅｒｉｃａｌＰｂＳｎａｎｏｐａｒｔｉｃｌｅｓｗｅｒｅａｆｆｅｃｔｅｄｂｙａｌｋｙｌｃｈａｉｎｔｅｍｐｌａｔｅａｎｄｍｉｃｒｏｓｏｆｔｔｅｍｐｌａｔｅｍｉｃｅｌｌｅｓｆｒｏｍｓｕｒｆａｅｔａｎｔ．Ｋｅｙｗｏｒｄｓ：ＰｂＳ；ｓｐｈｅｒｉｃａｌｎａｎｏｅｒｙｓｔａｌ；ＣＴＡＢ

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。

Synthesis and Characterization of Li(Li0.23Mn0.47Fe0.2Ni0.1)O2 Cathode Material for Li-ion Batteries

retention
Li(Li0.23Mn0.47Fe0.2Ni0.1)O2 compound synthesized easily at low temperature by the proposed citric acid assisted sol-gel process is a promising cathode material for Li-ion batteries.
57
EP
TE D
(1−z)Li[Li1/3Mn2/3]O2−(z)Li[Mn0.5−yNi0.5−yCo2y]O2
M AN U
[11]. to
2
Li2MnO3–LiCo1/3Ni1/3Mn1/3O2
SC
The 4.0~4.5V)
storage power station applications. Therefore, new cathode materials with high capacity, low cost and environment friendly have been investigated thoroughly in recent years [1]. Among them the layered Li2MnO3-based solid solution materials have attracted more attention of the researchers, such as Li2MnO3-LiMO2 (M = Ni, Cr and Co) [2–5], LiNiO2–Li2MnO3–LiCoO2 [8], and [6], Li2MnO3–LiNi1−xCoxO2 [7], [9], [10], above-mentioned

四氧化三铁

共沉淀法制备四氧化三铁纳米磁性材料引言：磁性是物质的基本属性，磁性材料是古老而用途十分广泛的功能材料。

磁挂材料与信息化、自动化、机电一体化、国防、国民经济的方方面面紧密相关．纳米磁性材料是20世纪70年代后逐步产生、发展，壮大而成为最富有竞争力与宽广应用前景的新型磁性材料。

纳米磁性材料的特性不同于常规的磁性材料,其原因是与磁相关联的特征物理长度恰好处于纳米量级，倒如：磁单畴临界尺寸，超顺磁性临界尺寸,交换作用长度以及电子平均自由路程等大致上处于l～1OOnm量级,当磁性体的尺寸与这些特征物理长度相当时就会呈现反常的磁学性质[1]。

磁性纳米材料除具有纳米材料的一般特性外还具有顺磁效应，其中Fe3O4纳米晶由于其超顺磁性、高表面活性等特性，已在磁流体、微波吸收、水处理、光催化、生物医药、生物分离等方面得到了广泛的应用，正在成为磁性纳米材料的研究热点。

目前制备磁性Fe3O4纳米晶的主要方法有沉淀法、溶剂热法、溶胶-凝胶法、微乳液法、微波超声法等[2-8]，这几种方法制得的磁性Fe3O4纳米晶在结构和性能方面都有一定的差异，因此在不同领域的应用往往要采用不同的制备方法。

其中共沉淀法即在含有两种或两种以上阳离子的可溶性溶液中加入适当的沉淀剂,使金属离子均匀沉淀或结晶出来，再将沉淀物脱水或热分解而制得纳米微粉。

共沉淀法有两种: 一种是Massart 水解法[9], 即将一定摩尔比的三价铁盐与二价铁盐混合液直接加入到强碱性水溶液中, 铁盐在强碱性水溶液中瞬间水解结晶形成磁性铁氧体纳米粒子。

另一种为滴定水解法[10], 是将稀碱溶液滴加到一定摩尔比的三价铁盐与二价铁盐混合溶液中, 使混合液的pH 值逐渐升高, 当达到6～7 时水解生成磁性Fe3O4纳米粒子共沉淀方法的最大优点是设备要求低、成本低、操作简单和反应时间短,便于在实验室内操作。

本文主要介绍共沉淀法合成纳米Fe3O4及浓度、熟化时间、pH、超声波对纳米Fe3O4粒径等性质的影响。

三核铜配合物的合成、表征及其催化性能

2018年第37卷第10期 CHEMICAL INDUSTRY AND ENGINEERING PROGRESS·3879·化工进展三核铜配合物的合成、表征及其催化性能冷帅1，2，李云涛1，邓建国2（1西南石油大学材料科学与工程学院，四川成都 610500；2中国工程物理研究院化工材料研究所，四川绵阳 621900）摘要：采用溶剂热法合成了以三核碘化亚铜（CuI ）四面体结构为活性中心的硅氢加成反应催化剂，探讨了物料比对产物收率的影响。

结果说明了当配体与碘化亚铜的摩尔比为1∶6时，产物收率最高。

通过元素分析、傅里叶红外光谱分析、X 射线光电子能谱分析、X 射线单晶体衍射分析、紫外可见光光谱分析、热失重分析对配合物的化学组成、空间结构及性能进行表征，并进一步通过甲基苯基乙烯基树脂和甲基苯基含氢硅油的硅氢加成反应进行催化固化效果验证。

结果说明了在催化剂填加量为0.04%、固化温度为150℃的优化条件下反应24h ，共混体系固化效果最佳。

该配合物对硅氢加成反应具有很好的催化性能，并且原料成本低、制备方法简单、晶体颗粒方便储存，有望解决硅氢加成反应中贵金属催化剂的高成本问题。

关键词：配合物；催化剂；硅氢加成；碘化亚铜；晶体；合成中图分类号：TQ426.61；O643.36 文献标志码：A 文章编号：1000–6613（2018）10–3879–06 DOI ：10.16085/j.issn.1000-6613.2017-2271Synthesis, characterization and catalytic performance of tri-nuclearcopper complexLENG Shuai 1,2, LI Yuntao 1, DENG Jianguo 2(1School of Materials Science and Engineering, Southwest Petroleum University ，Chengdu 610500，Sichuan ，China ；2Institute of Chemical Materials ，China Academy of Engineering Physics ，Mianyang 621900，Sichuan ，China)Abstract ：A complex catalyst with tetrahedron structure copper(I) iodide (CuI) as active center has been synthesized by solvent-thermal method ，which is then used in hydrosilylation. The effect of the material ratios on the product yield has been discussed in depth. The results show that when the molar ratio of ligand to CuI is 1∶6，the highest yield is obtained. The chemical composition ，spatial structure and properties of the catalyst have been studied by elemental analysis ，Fourier transform infrared spectroscopy analysis ，X-ray photoelectron spectroscopy analysis ，X-ray single crystal diffraction analysis ，UV-visible spectroscopy analysis and thermogravimetric analysis, respectively. Furthermore ，the catalytic performance has been tested by the hydrosilylation reaction of methylphenyl vinyl resin and methylphenyl hydro-silicone oil. The results indicate that the curing effect is the best when the blending system reacts for 24h under the addition of 0.04% complex at 150℃. The complex shows very good catalytic performance in hydrosilylation ，and can be synthesized with the advantages of low-cost raw materials ，simple preparation method and convenient storage. It is promising to solve the problem of the high cost of traditional precious metal catalysts in hydrosilylation.Key words ：complex ；catalyst ；hydrosilylation ；copper(I) iodide ；crystal ；synthesis合材料。

结构化学英语

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

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 ratio.AcknowledgmentThis study was supported by Korean Research Foundation through project no.KRF-2004-005-D0009.References1.Janbey,A.;Pati,R.K.;Tahir,S.;Pramanik,P.A new chemical route for the synthesis of -Al 2O 3.J.European Ceramic Society 2001,21,2285–2289.2.Pathak,L.C.;Singh,T.B.;Das,S.;Verma, A.K.;Ramachandrarao,P.Effect of pH on the combustion synthesis of nano-crystalline alumina powder.Materials Letter 2002,57,380–385.3.Kiminami,R.H.G.A.;Morelli,M.R.;Folz,D.Z.;Clark,D.C.;Clark,D.E.Microwave synthesis of alumina powders.American Ceramic Society Bulletin 2000,79,63–67.4.Wu,Y.Q.;Zhang,Y.F.;Huang,X.X.;Guo,J.K.Preparation of plate like nano alpha alumina particles.Ceramic International 2001,27,265–268.5.Karasev,V.V.;Onishchuk,A.A.;Lotov,O.G.;Baklanov,A.M.;Zarko,V.E.;Panﬁlov,V.N.Charges and fractal properties of nanoparticles—Combustion products of aluminum bustion Explosion and Shock Wave 2001,37,734–736.6.Ichinose,N.Superﬁne Particle Technology 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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。

四氧化三铁——精选推荐

四氧化三铁共沉淀法制备四氧化三铁纳⽶磁性材料引⾔：磁性是物质的基本属性，磁性材料是古⽼⽽⽤途⼗分⼴泛的功能材料。

磁挂材料与信息化、⾃动化、机电⼀体化、国防、国民经济的⽅⽅⾯⾯紧密相关．纳⽶磁性材料是20世纪70年代后逐步产⽣、发展，壮⼤⽽成为最富有竞争⼒与宽⼴应⽤前景的新型磁性材料。

纳⽶磁性材料的特性不同于常规的磁性材料,其原因是与磁相关联的特征物理长度恰好处于纳⽶量级，倒如：磁单畴临界尺⼨，超顺磁性临界尺⼨,交换作⽤长度以及电⼦平均⾃由路程等⼤致上处于l～1OOnm量级,当磁性体的尺⼨与这些特征物理长度相当时就会呈现反常的磁学性质[1]。

磁性纳⽶材料除具有纳⽶材料的⼀般特性外还具有顺磁效应，其中Fe3O4纳⽶晶由于其超顺磁性、⾼表⾯活性等特性，已在磁流体、微波吸收、⽔处理、光催化、⽣物医药、⽣物分离等⽅⾯得到了⼴泛的应⽤，正在成为磁性纳⽶材料的研究热点。

⽬前制备磁性Fe3O4纳⽶晶的主要⽅法有沉淀法、溶剂热法、溶胶-凝胶法、微乳液法、微波超声法等[2-8]，这⼏种⽅法制得的磁性Fe3O4纳⽶晶在结构和性能⽅⾯都有⼀定的差异，因此在不同领域的应⽤往往要采⽤不同的制备⽅法。

其中共沉淀法即在含有两种或两种以上阳离⼦的可溶性溶液中加⼊适当的沉淀剂,使⾦属离⼦均匀沉淀或结晶出来，再将沉淀物脱⽔或热分解⽽制得纳⽶微粉。

共沉淀法有两种: ⼀种是Massart ⽔解法[9],即将⼀定摩尔⽐的三价铁盐与⼆价铁盐混合液直接加⼊到强碱性⽔溶液中, 铁盐在强碱性⽔溶液中瞬间⽔解结晶形成磁性铁氧体纳⽶粒⼦。

另⼀种为滴定⽔解法[10], 是将稀碱溶液滴加到⼀定摩尔⽐的三价铁盐与⼆价铁盐混合溶液中, 使混合液的pH 值逐渐升⾼, 当达到6～7 时⽔解⽣成磁性Fe3O4纳⽶粒⼦共沉淀⽅法的最⼤优点是设备要求低、成本低、操作简单和反应时间短,便于在实验室内操作。

本⽂主要介绍共沉淀法合成纳⽶Fe3O4及浓度、熟化时间、pH、超声波对纳⽶Fe3O4粒径等性质的影响。

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.。

王文 - 哈尔滨工业大学

材料科学与工程学院王文工学博士副教授；硕士生导师+86-451-86402040-8404wangwen@主要研究方向(1)多铁性CoFe2O4/PbMg1/3N2/3-PbTiO3复合薄膜的取向生长与磁电耦合效应(哈工大科研创新基金HIT.NSRIF. 2009031)(2)SrBi2Ta2O9,Bi4-x LaxTi3O12和Pb(Zr,Ti)O3纳米线(管)的溶胶凝胶合成与表征(2006.3至今黑龙江省青年基金NoQC05C06,国家自然科学基金No50872024)(3)SrBi2Ta2O9和Bi4-x LaxTi3O12铁电薄膜及陶瓷的微观组织结构与性能(2002.3至今,国家自然科学基金No50502013and No50172012)(4)稀土掺杂BaTiO3陶瓷的PTC效应(5)溶胶-凝胶工艺制备Al2O3包覆金属粉体的涂层制备工艺研究社会兼职主要学术成果1.W.Wang,Y.Zhou,S.Chen,F.Ye,D.C.Jia.Preparation of strontium bismuth tantalum(SBT)fine powder by Sol-Gel process Using bismuthsubnitrate as bismuth source.Journal of materials science and technology.2001,17(1):25-262.Y.Zhou,W.Wang,D.C.Jia,F.Ye.Synthesis and Characterization o f Strontium Bismuth Tantalum(SBT)Fine Powder by a ModifiedSol-Gel Process Using Bismuth Subnitrate as Bismuth Source.Materials chem ical and physical,2002,77:60-643.W.Wang,D.C.Jia,Y.Zhou,F.Ye.Synthesis and characterization of nanosized SrBi2Ta2O9powder by a novel sol-gel process.MaterialResearch Bulletin.2002,37:2517-25244.W.Wang,D.C.Jia,Y.Zhou,F.Ye.Synthesis and properties of SBT powder and film prepared by a sol-gel process.Ceramics International,2002,28:609-6155.WANG Wen,JIA Dec hang,ZHOU Yu.Preparation and properties of SrBi2.2Ta2O9thin film.Journal of central south university of technology,2005,12(4):376-3796.Wen Wang,Ke Yu,Hua Ke,Haijun Niu,Dechang Jia,Yu Zhou.Fabrication and properties of SrBi2Ta1-x Nb2O9ferroelectric ceramics.KeyEngineering Materials,2007,336-338,143-1457.Ming Feng,Wen Wang,Yu Zhou.Synthesis and characterization of ferroelectric SrBi2Ta2O9nanotubes arrays.Journal of Sol-Gel Scienceand Technology,2009,52:120-1238.M.Feng,W.Wang,H.Ke,J.C.Rao,Y.Zhou.Highly(111)-oriented and pyrochlore-freee PNM-PT thin films derived from a modified sol-gelprocess.Journal of alloys and compounds,2010,495,154-157。

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 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