Extending the π-system of inverted solvatochromic phenolate-based dyes shifts their inversion point due to an increment in their sensitivity to solvent polarizability
Two pairs of phenolate-based dyes with a π-connecting system of different lengths were synthesized, and their spectral variations were investigated in pure solvents of variable polarity and methanol-dichloromethane solvent mixtures. All the dyes studied exhibited inverted solvatochromism, and multiparametric analysis of their solvatochromic absorption bands of these dyes revealed that the solvent acidity
The positive halochromism of phenolate dyes in hydroxylic solutions of tetraalkylammonium cations
作者:Marcos Caroli Rezende、Moisés Dominguez、Andrés Aracena
DOI:10.1016/j.saa.2011.11.010
日期:2012.2
By contrast with the negative halochromic behaviour shown by phenolate betaines in the presence of alkaline and alkaline-earth cations, the addition of tetraalkylammonium salts to hydroxylic solutions of these dyes generate bathochromic shifts of their charge-transfer band. This positive halochromic behaviour by organic cations was examined systematically and its origin rationalized by nonspecific changes of the medium permittivity, and by specific dye-cation interactions in solution. (C) 2011 Elsevier B.V. All rights reserved.