稀土三酞菁夹心化合物混合LB膜的研究

【作者】 范迎菊；

【导师】 姜建壮；

【作者基本信息】 山东大学 ， 无机化学， 2005， 硕士

【摘要】 具有高度三维共轭结构的对称的和不对称的三明治型(sandwich-type)稀土及一些其它金属的酞菁、卟啉类配合物具有独特的光、电和磁性质,该类型化合物具有扩展的平面共轭分子结构和较小的HOMO-LUMO能级差,因而显示出特殊的光谱学、电化学及其它物理化学性能;在分子导体,分子磁体,分子元器件,液晶和非线性光学材料等多方面具有潜在的应用价值。自20世纪60年代Kirin首次制得这类化合物以来,吸引着人们越来越浓厚的研究兴趣。人们对其进行了各方面研究,如结构、光谱、各种特性、并发展了各种合成方法。用一定的成膜技术将其制备成微观上分子排列高度有序的薄膜材料,将更能体现出该类化合物优良的物化特性,由于酞菁化合物的平面分子结构及环间强烈的非共价相互作用,因此成为超分子组装中有用的构件块(building blocks)。Langmuir-Blodgett(LB)技术可在分子水平上对构件块进行组装,因此也成为组装酞菁化合物超分子体系的有效手段。该技术也用于稀土双酞菁等夹心化合物的超分子体系的组装,发现由于分子高度有序的组织、导电性、光学性质等呈现出明显的各向异性。本论文中我们运用LB技术将三明治型三酞菁稀土的配合物(Pc)M[Pc(OC8H17) 8] M[Pc(OC8H17) 8] (M=Gd,Dy,Er)组装成有序超分子体系,然后采用了压力-面积曲线,紫外-可见吸收,偏振紫外吸收,低角X射线衍射,透射电子显微镜(TEM)等多种手段对有序超分子组装体系的结构进行了表征,结果如下:用π-A等温线研究了(Pc)M[Pc(OC8H17) 8] M[Pc(OC8H17) 8] 及(Pc)M[Pc(OC8-H17) 8] M[Pc(OC8H17) 8] /SA(摩尔比1:4) (M=Gd,Dy,Er)在气/液界面的单层膜。结果表明,纯膜及混和膜均可在气/液界面上形成稳定的单层膜,硬脂酸的加入有效改善了配合物分子的聚集。同时得到了在气/液界面上的极限分子面积,发现分子的极限分子面积随中心离子半径的增加而增大,硬脂酸与(Pc)M[Pc(OC8H17) 8] M[Pc(OC8H17) 8] (M=Gd,Dy,Er)为理想混合。用垂直提拉法制备了(Pc)M[Pc(OC8H17) 8] M[Pc(OC8H17) 8] /SA(摩尔比 1: 4) (M=Gd,Dy,Er)的多层LB膜,并用紫外一可见吸收光谱、偏振紫外一可见吸收光谱研究了二种化合物在LB膜中的排列。与溶液中的吸收光谱比较,化山东大学硕士学位论文合物LB膜的吸收光谱中Q吸收带发生红移,说明LB膜中三酞蓄聚集形成了J聚集体,这种聚集现象是由于激子相互作用引起的。偏振紫外一可见吸收光谱的研究结果表明,混合LB膜中,三酞著分子平面与基片之间成一定的夹角,夹角小于魔角。用低角X射线衍射实验表征了膜的结构。结果表明(Pe)M[pe(OCsH17)s」M[pe(OCSH,7)s」(M=Gd,Dy,Er)与SA的混合LB膜具有很好的层状结构。实验得到了一级Bragge衍射峰,根据Bragge方程计算出化合物单层膜的厚度分别为2.41nln(M=Gd,Dy),2.42nm(M=Er)。结合偏振紫外一可见吸收光谱测定的三酞著分子的取向角,可以认为取代稀土三酞著分子在气/液界面上长链向上伸展,在膜中呈faee一to一face柱状排列,edge一。n取向。单层厚度的实际观测结果与理论计算值恰好吻合。用TEM观察了20mN下(pe)Dy〔pe(OCSH17)s]Dy[pe(OCsH,7)s]纯膜及混合膜的单层膜,发现纯膜中分子发生了较强的聚集,有圆形大小不一的畴存在。混合膜中分子形成了分布均匀、尺寸相近的条带状结构,这表明加入硬脂酸后,分子进行了自组装,形成了超分子体系,膜中分子呈现出较好的二维有序性。关键词:稀土三酞著化合物,Langmuir一Bledgett技术,有序分子体系。更多还原

【Abstract】 Sandwich-type phthalocyaninato and / or porphyrinato rare earth complexes, possessing highly delocalized macrocycles, have attracted increasing interest in areas of semi- conductors, molecular metals, and molecular electronics due to their special optical and electronic properties. In particular, the bis(phthalo- cyaninato) rare earth compounds were noted for their sensitivity to such gases as NO2, SO2, CO, Br2, Cl2, and NH3. Because of the conjugated n molecular structure and the strong n-n interaction between the aromatic rings, phthalocyanine derivatives have been used as building blocks for ordered molecular systems. With the help of Langmuir-Blodgett technique, this kind of building block can be fabricated into well-ordered thin films. Preparing the monolayer and multilayers of different bis(phthalocyaninato) rare earth complexes by Langmuir-Blodgett mothod to meet the need of different applications attract many chemists. Naphthalocyanine possesses more extensive planar conjugated molecular structure and less HOMO-LUMO energy gap than phthalocyanine, therefore more unique spectroscopic, electrochemical, and physical-chemical properties have been expected for these naphthalocyanine derivatives.In this thesis, the ordered molecular assemblies of pure substituted triphthalocyaninesrare earth complexes and its mixture with stearic acid have been fabricated by Langmuir-Blodgett technique and characterized by surface pressure-area isotherms, electronic absorption spectra, polarized absorption spectra, low-angle X-ray diffraction patterns and Transmission Electron Microscope experiments. The results are briefly illustrated as follows:Monolayers and Langmuir-Blodgett(LB) films of the sandwich-type complex (Pc)M[Pc(OC8H17)8]M[Pc(OC8H17)g] (M=Gd,Dy,Er)and its mixture with stearic acid (SA) have been studied. Surface pressure-area isotherm indicates that stable monolayer was formed . The monolayer morphology was investigated by transmission electron microscopy (TEM). SA molecules effectively disperse the aggregates of the (Pc)M[Pc(OC8H17)8]M[Pc(OC8H17)8] (M=Gd,Dy,Er) molecules by the TEM observation .Columnar domains with the width of ca.40 nm and the length of several hundreds of nanometers appearing in the micrograph have ordered orientation .The monolayer of the complex mixed with SA was successfullydeposited on hydrophobic substrates by Langmuir-Blodgett method. The UV-vis absorption peaks of LB films are red shifted compared with those in solution, indicating the formation of J-aggregates. The orientation angle of the phthalocyanine ring with respect to the substrate was evaluated to be ca.52° according to the Polarized UV-vis spectra. The low-angle X-ray diffraction pattern showed a periodic distances for the mixed LB films of ca. 2.4 run. Based on all these considerations, a schematic arrangement of the complex molecules in LB films was suggested.更多还原