Photophysical properties of diphenylacetylene derivatives in the solution phase: Comparison with the dynamical properties of diphenylbutadiyne

Using femtosecond and picosecond transient absorption measurement techniques, we have investigated the dynamic behavior of the S2 state of diphenylbutadiyne (DPB) and its methoxy derivatives in solution. The observed much larger rate constants at room temperature and the smaller temperature-dependence of the S2→S1 internal conversion of the DPB derivatives compared to those of diphenylacetylene should be due to the large S2–S1 energy gap of DPBs.