Effects of chromophore interaction in photophysics and photochemistry of cyanine dyes

• Published in: International Journal of Photoenergy Vol. 2000; no. 1; pp. 23 - 30
• Main Authors: Tatikolov, A. S., Krasnaya, Zh. A., Shvedova, L. A., Kuzmin, V. A.
• Format: Journal Article
• Language: English
• Published: Hindawi Limiteds 01.01.2000; Hindawi Limited
• ISSN: 1110-662X; 1687-529X
• DOI: 10.1155/S1110662X00000040

Spectral and fluorescent properties of ketocyanine dyes (polyenic bis-ω,ω'-aminoketones) and cation-anionic polymethine dyes of various structures were studied. The symmetric ketocyanines were shown to have a long-wavelength absorption band bathochromically shifted in comparison with that of the asymmetric ketocyanines with the same total length of the polyenic chain. The nonlinear ketocyanines exhibit the additional short-wavelength band in their absorption spectra, which can be more intense than the longwavelength band. The absorption spectra of ion pairs of cation-anionic dyes with overlapping cation and anion bands contain a new intense short-wavelength band inactive in fluorescence excitation. These spectral peculiarities are explained on the basis of chromophore interaction model. It has also been shown that the T_1 levels of ketocyanine chromophores do not essentially interact with each other in a ketocyanine molecule in nonpolar solvents; in polar solvents this interaction becomes appreciable due to lowering the potential barrier for conjugation.