Solvent effects on photophysical properties of merocyanine 540

Absorption and corrected fluorescence emission spectra of merocyanine 540 ( MC 540) were recorded in solvents with different physico-chemical parameter s - dielectric constant epsilon (r), refractive index n. dipolarity/polariz ability pi*, hydrogen-bonding ability a. Hypsochromic shifts of their maxim s positions did not obey Lippert-Mataga equation. However, a correlation wi th pi*. and alpha was observed. Relative quantum yields phi (f) and rate co nstants of nonradiative deactivation processes k(ar) of the dye in differen t solvents based on steady-state measurements were estimated. Dependence on hydrogen-bonding ability was indicated - with increasing alpha, phi (f) de creased and k(ar) increased. The interaction between MC 540 and solvent mol ecules is discussed in terms of the different interactions contributing to the solvent stabilization of merocyanine dyes. Our results indicate that hy drogen bonding may contribute to solvent stabilization of MC 540. (C) 2001 Published by Elsevier Science B.V. All rights reserved.