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Advances in Physical Chemistry
Volume 2016 (2016), Article ID 6737494, 7 pages
Research Article

A Group Theoretical and Quantum Chemical Study of Electronic Absorption and Fluorescence, Vibrational Spectra, and Conformations of Trimethine Cyanine Dye Molecules

1Department of General and Theoretical Physics, Sumy State University, 2 Rimsky-Korsakov Street, Sumy 40007, Ukraine
2Department of Theoretical Physics, Aerospace Institute, National Aviation University, 1 Kosmonavta Komarova Prospekt, Kiev 03680, Ukraine

Received 13 October 2015; Revised 30 November 2015; Accepted 8 December 2015

Academic Editor: Sergei Tretiak

Copyright © 2016 Vita Solomko et al. 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.


The energetic structures and conformations of trimethine cyanine dye molecules were investigated. For research, group theoretical and quantum chemical calculation methods were used. The theoretical group analysis of electronic and vibrational structure of molecules was carried out. Also, the energetic structures and conformations of the molecule of this dye were studied. Research shows that the investigated molecule may reside in three different conformational states, one of which is highly symmetric (symmetry ) and the other two with low symmetry. The third conformer is characterized by lowering of binding energy of the electronic system by 0.23 eV, and the long-wavelength absorption band is shifted to lower energies. Also the group theoretical analysis of the trimethine cyanine molecule had allowed systematizing the vibrational and electronic quantum transitions and identifying the bands in the absorption spectra. It is shown that the excitation of the molecule in -state causes trans-cis-isomerization. The presence of the barrier of ~0.1 eV allows the fluorescence process to compete with isomerization process, but isomerization causes a decrease in the fluorescence quantum yield of the dye.