TEMPERATURE-DEPENDENT CONFORMATIONAL CHANGE AND INTRAMOLECULAR ENERGY-TRANSFER OF POLYSILYLENES

Fluorescence and fluorescence excitation as well as absorption spectra of dilute organic solutions of poly(di-n-butylsilylene) and poly(di-n-hexylsilylene) have been measured at different temperatures, and the dependence of the relative fluorescence quantum yields on temperature was determined. Evidence is presented showing that the energy transfer is occurring intramolecularly from helical to rodlike conformational segments for these polysilylenes. Analysis of the temperature dependence of the relative fluorescence quantum yields reveals that the transfer yield increases sharply with decreasing temperature at the temperatures near the conformational transition temperature. It is inferred that the transfer yield and rate increase as the rod segment content in the chain increases.