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International Journal of Photoenergy
Volume 2 (2000), Issue 1, Pages 23-30

Effects of chromophore interaction in photophysics and photochemistry of cyanine dyes

1Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin Str. 4, Moscow 117334, Russia
2Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Pr. 47, Moscow 117913, Russia

Copyright © 2000 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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 T1 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.