Synthesis and spectroscopic studies of novel photochromic benzodithiacrown ethers and their complexes

Abstract

New styryl dyes containing the benzodithia-18-crown-6 fragment have been synthesized and their photoisomerization reactions and complexes with Hg²⁺ and Ag⁺ cations have been investigated by steady-state electronic and resonance Raman spectroscopy. (4-Formylbenzo)dithia-18-crown-6, N-carboxypropyl- and N-carboxybutyl-2-methylbenzothiazolium bromides have also been prepared as intermediates for the styryl dye syntheses. Changes in vibrational resonance Raman spectra observed on complexation with Ag⁺ and Hg²⁺ cations or on variation of solvent polarity have been correlated with changes in the UV–VIS absorption maxima of the dyes. Preliminary assignments of the observed Raman bands to particular vibrations are made.