Excited state recoordination reaction in metal complexes of crowned styryl dye

S.I. Druzhinin, S.P. Gromov

Internet Journal of Science. Biological Chemistry. (in print)

ABSTRACT. The absorption and fluorescence spectra of styryl dye of an indolenine series and its 15-azacrowned-5 derivative in MeCN at the presence of trifluoroacetic acid and lithium, sodium, magnesium, and calcium perchlorates were investigated. It was shown, that the absorption spectrum of crowned dye is shifted significantly to shortwavelength by 7280, 1210, 1970, 5920 and 5060 cm-1 as the protonation and metal complex formation takes place. Similar shift of the fluorescence spectrum is rather small (-, 190, 30, 1010, and 260 cm-1). The protonated dye does not fluoresce. The fluorescence quantum yield is increased from 0.049 to 0.095, 0.087 and 0.079 as going from the crowned dye to its complexes with lithium, sodium, and calcium cation. On the basis of similar shifts of the absorption spectrum of the calcium complex and protonated dye it makes a conclusion, that the conjugation of macrocyclic nitrogen atom with dye p-system is breaked owing to metal complex formation in the ground state. The recoordination reaction in metal complexes of crowned styryl dye and reduction of this conjugation take place in exited state.

Laboratory of Laser Photonics