Photophysical processes in the molecular complexes of 1,2,4,5-tetracyanobenzene with aromatic donors

Abstract

The photophysical parameters of the (TCNB)–mesitylene molecular complex were investigated using a 1 MW nitrogen gas laser. Increasing amounts of CH₃CN cause a decrease in the quantum yield and lifetime of the EDA fluorescent state, which was attributed to a decrease in the radiative rate constant and an increase in the non-radiative rate constants. The yield of TCNB–benzene triplet state, as a function of CH₃CN, was monitored by direct infrared observation and by measuring the yield of anthracene triplet generated as a result of energy transfer. The reduction in the EDA triplet state yield as CH₃CN increased, was shown to be due to the decrease in the EDA singlet state lifetime. No triplet state was monitored for the TCNB–mesitylene system. The change in the S₁→ S^{[graphic omitted]}₀ transition with CH₃CN was postulated to be caused by solvent destabilization of the ground Franck–Condon state S^{[graphic omitted]}₀.