Fluorescence of crowned butadienyl dye and its metal complexes

The absorption and fluorescence spectra of complexes of butadienyl dye (1) with lithium, sodium, magnesium, and calcium cations in MeCN were investiga ted. The addition of Li, Na, Mg, and Ca perchlorates to the solution of dye 1 in acetonitrile results in a significant (up to 5900-cm(-1)) short-wavel ength shift of the absorption spectrum and a small (about 200-cm(-1)) short -wavelength shift of the fluorescence spectrum. The recoordination reaction in metal complexes of 1 takes place by intramolecular mechanism. The fluor escence quantum yield of 1Li(+), 1Na(+), and 1Ca(2 divided by) is approxima tely two times higher than that for 1. It was supposed that Li+ cation coor dinates predominantly with oxygen atoms of macrocycle and, hence, influence s weakly macrocycle nitrogen atoms conjugated with a molecule pi-system.