EXCITED-STATE RELAXATION PROCESSES OF CROWNED STYRYL DYES AND THEIR METAL-COMPLEXES

The fluorescence of novel crowned styryl dyes and their complexes with sodium cation was studied. The fluorescence quantum yield of crowned styryl dye is higher than that of non-crowned ones. While absorption a nd fluorescence spectra of a styryl dye are shifted to high frequency regions, its fluorescence quantum yield in the absence of photoisomeri zation is practically unchanged, and the rate constant of its temperat ure fluorescence qienching rises as it forms a complex with the metal ion. The relaxation processes of photoisomerization and recoordination are considered. The adiabatic change of metal ion coordination in cro wn cycle may proceed in the excited state. The trans-cis photoisomeriz ation of styryl dyes and their metal complexes is a barrierless reacti on.