| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1235815 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2012 | 6 Pages |
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.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The halochromic behaviour of tetraalkylammonium salts was investigated in hydroxylic solvents. ► The observed positive halochromism depended on the solvent, and on the dye and cation structures. ► The effect was rationalized by invoking non-specific and/or specific solute–solvent interactions. ► Non-specific effects originate from a decrease of the medium permittivity by addition of the organic salt. ► Specific effects originate from dye–cation interactions, and were simulated with theoretical calculations.
