Solvatochromic behavior of non-activated indolinobenzospiropyran 6-carboxylates in aqueous binary solvent mixtures. Part II

The solvatochromic behavior of non-activated indolinobenzospiropyran 6-carboxylates SP-1-2 in aqueous binary solvent mixtures was investigated. Marked negative solvatochromism was exhibited by SP-1-2 in the whole region of solvent polarity examined. Excellent linear relationships were observed between lambda(max) and the solvent polarity parameter, E-T(BM), for the aqueous binary solvent mixtures. The sensitivity of the binary solvent system toward the transition energies of the MC form was highest in the water-methanol solvents in all SP molecules examined. As of other merocyanine dyes in neat solvents, the MC form of spiropyran 6-carboxylates in the aqueous binary solvents showed a negative solvatochromism. The aqueous solvent was found to affect the solvatochromic behavior of the merocyanine dyes by increasing the sensitivity of the chrornophore to the effects of solvation via H-bonding. (c) 2006 Elsevier Ltd. All rights reserved.