Models for polysilane high polymers. Room-temperature solution fluorescence quenching in linear Si₁₀Me₂₂, Si₁₆Me₃₄ and poly(methylpropylsilane) by carbon tetrachloride

Abstract

Carbon tetrachloride quenches the intensity and lifetime of the room-temperature fluorescence of poly(methylpropylsilane) and its model compounds, permethylated n-decasilane and n-hexadecasilane, in n-hexane and n-hexadecane. The process is dominated by static quenching. Changes in fluorescence shape as a function of quencher concentration show that the lowest energy chromophores extend most in space, supporting the standard segment model of polysilane electronic structure. The usual analysis leads to static quenching volumes of approximately 1800 Å3 for Si10Me22 and approximately 3500 Å3 for Si16Me34. Unlike these, the quenching volume of poly(methylpropylsilane) depends on the excitation wavelength (approximately 800-1400 Å3). It is much larger than that of poly(di-n-hexylsilane), which depends strongly on excitation wavelength (approximately 10-1200 Å3). A tentative interpretation of these unusual observations is proposed. © 1992.