PHOTOCHROMISM OF STYRYL CYANINE DYES IN SOLUTION

The photochemical and spectral behavior of two styryl cyanine dyes wer e studied in different solvents. The experimental results indicate tha t in solution the compounds exist in two forms-closed and open. The eq uilibrium is strongly shifted toward the closed form. From the absorpt ion and luminescence properties, the conclusion can be made that absor bed energy can be lost through different channels: photochemical close d-open form and cis-trans isomerization and through photophysical proc esses such as fluorescence. The quantum yield of the process, closed-o pen form is measured. The reasons for the photochromic behavior of the se compounds are discussed. (C) 1998 Elsevier Science S.A.