Abstract
The behavior of the bond orders in symmetric model polymethine dyes has been investigated by the HMO, PPP, and CNDO/2 methods. It has been established that the greatest equalization of the bonds is achieved in the case of dyes with moderately basic terminal groups. In other cases, alternation of the bond orders, which diminishes with increasing length of the polymethine chain and attenuates with increasing distance from the end, has been discovered at the ends of the polymethine chain. The amplitude of the alternation of the bond orders in a polymethine chain is greater, the more the basicity of the terminal groups, as characterized by the electron-donor parameter Φo (0 ⩽ Φo ⩽ 90°), deviates in either direction from the mean (Φo = 45°). It is considerably smaller in the first excited state than in the ground state. The π-electronic approximation is a correct method for describing the electronic structure of a polymethine chain. The neglect of the σ electrons can distort the bond orders of the terminal groups.
Similar content being viewed by others
Literature cited
G. G. Dyadyusha and A. D. Kachkovskii, “Influence of structural changes in the polymethine chains of symmetric cyanine dues on their absorption spectra,” Ukr. Khim. Zh.,44, No, 10, 1069–1075 (1978).
A. A. Ishchenko, N. A. Derevyanko, M. A. Kudinova, et al., “Chemical structure and form of the absorption bands of pyrylocyanine dyes,” Teor. Eksp. Khim.,13, No. 6, 828–831 (1977).
G. G. Dyadyusha, I. V. Repyakh, and A. D. Kachkovskii, “Quantum-chemical investigation of the charge distribution in cations of symmetric polymethine dyes,” ibid,20, No. 4, 398–406 (1984).
C. A. Coulson and H. C. Longuet-Higgins, “The electronic structure of conjugated systems,” Proc. Roy. Soc., A,191, No. 1, 39–47 (1947).
R. Mulliken, “Electronic population analysis on LCAO-MO molecular wave functions. 1,” J. Chem. Phys.,23, No. 10, 1833–1840 (1955).
G. G. Dyadyusha, M. A. Al'perovich, V. S. Tyurin, and A. D. Kachkovskii, “First electronic transitions in symmetric and asymmetric polymethine dyes,” Ukr. Khim. Zh.,51, No. 3, 298–302 (1985).
B. Zeimer and S. Kulpe, “Die Molekül- and Kristallstrukture des 3,3-Diäthylbenzthiacarbozianin-p-toluolsulfonats, C28H28N2O3S3·1/2H2O,” J. Prakt. Chem.,317, No. 2, 199–213 (1975).
B. Zeimer and S. Kulpe, “Die Molekül- and Kristallstrukture des Bis-dimethyl-pentamethinzianin-chlorid-dihydrats, C9H21C1N2O2,” ibid,317, No. 2, 185–198 (1975).
Yu. A. Kruglyak, V. S. Kvakush, G. G. Dyadyusha, and V. I. Khil'chenko, Calculation Methods in Quantum Chemistry [in Russian], Naukova Dumka, Kiev (1967), 162 pages.
K. Ohno, “Some remarks on the Pariser-Parr-Pople method,” Theor. Chim. Acta,2, No. 3, 219–227 (1964).
N. Mataga and K. Nishimoto, “Electronic structure and spectra of nitrogen heterocycles,” Z. Phys. Chem. (Munich),13, No. 3/4, 140–157 (1957).
G. G. Dyadyusha, A. A. Ishchenko, N. A. Derevyanko, et al., “Investigation of the solvatochromism of cyanine dues by the method of moments,” Teor. Eksp. Khim.,15, No. 4, 412–416 (1979).
V. A. Mostovnikov, A. N. Rubinov, M. A. Al'perovich, et al., “Dependence of the luminescence and lasing properties of solutions of polymethine dyes on their structure,” Zh. Prikl. Spektrosk.,20, No. 1, 42–47 (1974).
A. I. Tolmachev, N. A. Derevyanko, and A. A. Ishchenko, “Pyrylocyanines. 16. Tetraphenylated 2- and 4-pyrylocyanines,” Khim. Geterotsikl. Soedin., No. 9, 1178–1183 (1982).
K. B. Wiberg, “Application of the Pople-Santry-Segal CNDO method to the cyclopropylcarbinyl and cyclobutyl cation and to bicyclobutane,” Tetrahedron,24, No. 3, 1083–1096 (1968).
Author information
Authors and Affiliations
Additional information
Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 2, pp. 138–146, March–April, 1985.
Rights and permissions
About this article
Cite this article
Dyadyusha, G.G., Repyakh, I.V. & Kachkovskii, A.D. Quantum-chemical investigation of bond orders in symmetric polymethine dyes. Theor Exp Chem 21, 131–139 (1985). https://doi.org/10.1007/BF00945186
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00945186