Effect of electrolyte on ground and excited state properties of a ketocyanine dye in non-aqueous solvents

UV-Vis spectroscopic properties of a ketocyanine dye have been studied in solutions of lithium perchlorate, sodium perchlorate, tetramethyl ammonium bromide and tetrabutyl ammonium bromide in non-aqueous solvents. In an aprotic medium, the maximum wavelengths of absorption and emission shift towards red with the addition of electrolytes. Li+ ion is most effective in bringing about the change in spectral properties. Complexation of Li+ ion with both ground and the excited CT state has been observed. Life time of the S-1 state increases with the addition of electrolytes. No significant change in spectroscopic parameters, however, is observed in a protic medium. (C) 2005 Elsevier B.V. All rights reserved.