Studies of solvation of ketocyanine dyes in homogeneous and heterogeneous media by UV/Vis spectroscopic method

Solvation characteristics of ketocyanine dyes (I-VI) have been investigated in pure solvents and heterogeneous media by absorption and fluorescence st udies. The dyes are good reporters of solvent polarity. In protic solvents they exist as equilibrium mixtures of bare and hydrogen-bonded form in the ground state (S-0), the latter being the emitting species. In aprotic solve nts of low polarity association of the S-1 state of the dye takes place. In aqueous micellar media the dye resides at the micelle-water interface. The binding constant for dye-micelle interaction has been determined. Fluoresc ence data in beta -cyclodextrine solution resemble that for that neutral mi cellar solution indicating that the interaction between the -OH group of th e heterogeneous part (micelle/cyclodextrine cavity) and the carbonyl oxygen of the dye is important in both the cases. (C) 2000 Elsevier Science B.V. All rights reserved.