Preparation and Photoelectronic and Electrochemical Properties of Oligo(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(alkylphenylsilylene)s

摘要

We oligomerized 2,5-dibromo-1,1-diisopropyl-3,4-diphenyl-2,5-silole with dichloroalkylphenylsilanes utilizing n-BuLi to yield conjugated oligo(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(alkylphenylsilylene)s. Gel permeation chromatography measurements confirm that the synthesized materials are oligomeric. In addition, the prepared oligomers show characteristic diene stretching bands at 1579-1599 cm(-1) in their FT-IR spectra. Furthermore, the oligomers are highly soluble in common organic solvents such as tetrahydrofuran and chloroform. In tetrahydrofuran, the oligomers show strong maximum electronic absorption bands at 253-292 nm with molar absorptivities of 1.61 x 10(2) to 2.57 x 10(4) /cm M in their UV-vis electronic absorption spectra, indicating that the maxima are red-shifted by 5-8 nm compared to the 2,5-dibromo-1,1-diisopropyl-3,4-diphenyl-2,5-silole monomer, strong maximum electronic excitation bands at 292-312 nm, and strong maxima electronic emission bands at 385-396 nm in the emission fluorescence spectra. The emission and absorption spectra strongly suggest that the prepared silole-containing oligomers may be conjugated through the oligomer backbone. In particular, cyclic voltammetry measurements of oligo(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(diphenylsilylene) deposited on a glassy carbon electrode in 1.0 M aqueous hydrogen chloride show two oxidation potentials at 0.98 and 1.61 V vs. Ag/Ag+, and two reduction potentials at 0.00 and -1.93 V vs. Ag/Ag+. The oligomers were stable on heating to 200 degrees C under nitrogen, as determined by thermogravimetric analysis, losing between 4 and 23 of their starting weights.