Photochromism of styryl cyanine dyes in solution

The photochemical and spectral behavior of two styryl cyanine dyes were studied in different solvents. The experimental results indicate that in solution the compounds exist in two forms-closed and open. The equilibrium is strongly shifted toward the closed form. From the absorption and luminescence properties, the conclusion can be made that absorbed energy can be lost through different channels: photochemical closed-open form and cis-trans isomerization and through photophysical processes such as fluorescence. The quantum yield of the process, closed-open form is measured. The reasons for the photochromic behavior of these compounds are discussed. (C) 1998 Elsevier Science S.A.