Photophysics of Some Substituted Diphenylmethylenes

Article abstract of DOI:10.1021/j100245a021

Absorption, emission, and excitation spectra, fluorescence decay times, and quantum yields of a series of substituted diphenylmethylenes have been measured in various rigid organic matrices at low temperatures.Substitution on the phenyl ring led to a decrease in lifetime, the greatest effect being observed in the dibromo compound, the lifetime of which was 10percent that of the unsubstituted compound.In addition, there was a small but noticeable external heavy atom effect on the decay times.The fluorescence quantum yields of some of the substituted diphenylmethylenes were found to depend on the energy of excitation.Changes in the absorption spectra in the temperature range between 4 and 95 K may be the result of appreciable population of close-lying singlet and triplet levels in the ground state at 95 K.The spectral changes were irreversible, however, possibly implying geometrical configuration changes.