Synthesis And Properties Of Functional Silane And Polysilane

Functional silane is the silane that hydrogen atom on silane was substituted by organic functional group. Polysilane is a kind of Si-Si bonding polymer including Si atoms in main chain. It is a-conjugated linear polymer, treated as "molecule wire" with semiconductor properties. When functional silane or polysilane is introduced into theπ-conjugated system, the intramolecular charge transfer mechanism was influenced for o-7t interaction. Some novel optoelectric properties can be obtained, such as nonlinear optic behavior, photon-absorption property, and solvatochromism, which can be applied in the area of optic information processing, optical fiber communication, laser frequency conversion, optoelectronic device, and photo sensor. In the thesis, a series of functional silane were prepared by introducing the nitrogen-containing functional groups with electron-donor and electron-acceptor properties. A series of side-chain polyether functional polysilanes were also prepared and show well soluble properties.The reaction of dimethyldi(4-N,N-dimethylaminophenyl)silane and chloroplatinic acid in acetone was studied. The structures of the cleavage products were fully characterized by FT-IR, NMR and ESI MS. One of the cleavage products was characterized by single crystal X-ray diffraction. It was found that both Si-C and C-N bonds in such functional silane were cleavaged catalyzed by chloroplatinic acid. Some crystal with supramolecular structure was obtained by the assembly of chloroplatinic acid and cleavage product through acid-base effect and hydrogen-bond effects. Based on the experimental data, the cleavage mechanism was discussed.Phenylene-containing functional silane conjugated with electron-acceptor groups,4-nitrile benzyl, was synthesized. Its optoelectrical properties were studied in different solvents. As a result, the fluorescent self-quench behavior of the compound was found following the change of solution concentration in 2-propanol, THF, and CH2Cl2. In addition, the fluorescence intensity of the compound exhibits strongly concentration-dependent in concentration range of 1.0x10-5～9.0x10-5 mol·L-1. Based on the results of quantum calculations, investigation of frontier orbitals, and analysis of the solid state crastal stack structures, the corresponding charge transfer model was built. It indicates that intramolecular photoinduced charge transfer in silicon-bridge compound is interdicted completely for the electron-acceptor properties of the two teminal nitrogen-containing function groups. However, intermolecular charge transfer effect was strengthened for the same reason. Meanwhile, its emission shows no response for the change of medium polarity.Phenylene-containing functional silanes conjugated with electron-donor group,4-N,N-dimethylphenyl, were synthesized. Their fluorescence emissions show response for the change of medium polarity. Such compounds exhibit positive solvatochromism. Moreover, the solvatochromism effect of the compound can be influenced by the substitution of silicon-bridge. In order to make sure the mechanism of such phenomenon, density functional theory (DFT) and Time-resolved density functional theory (TD-DFT) methods were utilized to investigate ground state and excited state, respectively. The result indicates that single-silicon-bridge interdicts the charge transfer as an insulator. However, intramolecular charge transfer occurs through space because of the strong electron-donor effects of the two terminal nitrogen-containing functional groups.A series of soluble polysilanes were prepared and show well soluble properties. Their structures were confirmed by FT-IR and NMR. The molecule weight of soluble polysilanes was characterized by GPC. Their thermal properties were investigated by TG. It indicated that the degree of polymerization of polysilane decrease following the increasing length of polyether. Their thermal properties were also characterized by DSC. It found that the Tg of them are all at about-90℃, but the Tc increase following the increasing length of polyether. The optoelectrical properties of synthesized polyether functional soluble polysilanes were studied, which indicates that the polysilanes shows good optoelectrical properties.A novel tetrazole-substituted phenylsilane was synthesized. Its structure was fully characterized by FT-IR, NMR and ESI MS. The crystal structure was characterized by single crystal X-ray diffraction. For successful going of lithiation reaction, alkylation of N-H in tetrazole ring with substituent (methyl, ethyl, and isopropyl) was studied. The results indicate that isopropyl group can survive under conditions of lithiation reaction. In addition, this silane shows well optoelectrical properties in THF and CH2C12, respectively.