Synthesis, Photoelectronic, and Electrochemical Properties of Poly[(1,1-dihexyl-3,4-diphenyl-2,5-silolene)-co-(disubstitutedsilylene)]s

摘要

Copolymerization of 2,5-dibromo-1,1-dihexyl-3,4-diphenyl-2,5-silole with dichlorodisubstitutedsilanes using n-butyllithium was performed to synthesize conjugated polycarbosilanes of poly[(1,1-dihexyl-3,4-diphenyl-2,5-silolene)-co-(disubstitutedsilylene)]s such as poly[(1,1-dihexyl-3,4-diphenyl-2,5-silolene)-co-(dimethylsilylene)], poly[(1,1-dihexyl-3,4-diphenyl-2,5-silolene)-co-(diethylsilylene)], poly[(1,1-dihexyl-3,4-diphenyl-2,5-silolene)-co-(methylphenylsilylene)], poly[(1,1-dihexyl-3,4-diphenyl-2,5-silolene)-co-(diphenylsilylene)], and poly[(1,1-dihexyl-3,4-diphenyl-2,5-silolene)-co-(tetramethyldisilylene)]. The characteristic diene stretching frequencies appeared at 1593-1601 cm(-1) in the Fourier-transform infrared spectra of all the polymers. The obtained materials were highly soluble in organic solvents such as tetrahydrofuran (THF) and chloroform. The molecular weights of the polymers were determined by gel permeation chromatography. The prepared materials in THF solvent showed strong absorption maximum peaks at 249-336 nm with molar absorptivities of 9.84 x 10(2) to 3.67 x 10(4) L/(cm center dot mol) in the UV-Vis absorption spectra, indicating red-shifts of 6-19 nm as compared with those of 2,5-dibromo-1,1-dihexyl-3,4-diphenyl-2,5-silole, strong excitation maximum peaks at 320-336 nm, and strong emission maximum peaks at 393-398 nm in the fluorescence emission spectra. All of the absorption and emission spectra strongly indicate that the obtained polycarbosilanes were conjugated along the polymer main chain. Cyclic voltammogram profiles showed that the oxidation and reduction potentials of the prepared polymers were very similar to each other, 0.91 to 1.06 and -0.97 to -1.18 V vs. Ag/Ag+, respectively. Thermogravimetric analyses showed that most of the polymers were thermally stable up to 200 degrees C in general, with a weight loss of 3-6% in nitrogen.