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 S1 state increases with the addition of electrolytes. No significant change in spectroscopic parameters, however, is observed in a protic medium.