Theoretical and Experimental Chemistry

, Volume 6, Issue 1, pp 28–33 | Cite as

Electronic aspects of the photodimerization of pyrimidine bases and their derivatives

  • Yu. A. Kruglyak
  • V. I. Danilov
  • V. A. Kuprievich
  • V. V. Ogloblin


Results of calculations for the lower excited triplet and singlet states of pyrimidine bases and a number of their derivatives, calculated by the self-consistent field (SCF) method for open shells and by the configuration interaction (CI) method for self-consistent orbitals, are presented. It is shown that excitation to the T1 and S1 states primarily affects the C5—C6 bond while triplet excitation is almost completely localized on this bond. This leads to exceptionally pronounced weakening of the C5—C6 bond in the T1 state. All other conditions being equal, the conditions in the T1 state are more favorable for the dimerization of the bases than in the S1 state. A correlation between the degree of localization of the triplet excitation at the C5—C6 bond and the ease of photodimerization has been established. The experimental facts associated with the formation of thymine free radicals in DNA are explained.


Free Radical Pyrimidine Experimental Fact Thymine Singlet State 
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  1. 1.
    R. Beukers and W. Berends, Biochim. et Biophys. Acta, 49, 181, 1961.Google Scholar
  2. 2.
    A. A. Lamola and J. P. Mittal, Science, 154, 1560, 1966.Google Scholar
  3. 3.
    A. A. Lamola and T. Yamane, Proc. Nat. Acad. Sci., U. S. A., 58, 443, 1967.Google Scholar
  4. 4.
    V. I. Danilov, Photochem. Photobiol., 6, 233, 1967.Google Scholar
  5. 5.
    G. G. Dyadyusha et al., Molekul. biol., 1, 539, 1967.Google Scholar
  6. 6.
    V. I. Danilov, O. V. Shramko, and G. G. Dyadyusha, Biofizika, 12, 544, 1967.Google Scholar
  7. 7.
    M. J. Mantione and B. Pullman, Biochim. et Biophys. Acta, 91, 387, 1964.Google Scholar
  8. 8.
    B. Pullman and M. J. Mantione, Biochim. et Biophys. Acta, 95, 668, 1965.Google Scholar
  9. 9.
    A. Imamura, H. Fujita, and C. Nagata, Bull. Chem. Soc. Japan, 40, 21, 1967.Google Scholar
  10. 10.
    H. Berthod et al., Intern. J. Quant. Chem., 1, 123, 1967.Google Scholar
  11. 11.
    A. Denis and A. Pullman, Theoret. Chim. Acta, 7, 110, 1967.Google Scholar
  12. 12.
    Yu. A. Kruglyak, G. G. Dyadyusha, V. A. Kuprievich, L. M. Podol'skaya, and G. I. Kagan, Methods of Calculating the Electron Structure and Spectra of Molecules [in Russian], Chapter 3, Naukova Dumka, Kiev, 1969.Google Scholar
  13. 13.
    Yu. A. Kruglyak, “Calculation of the electron structure of conjugated molecules and radicals by the self-consistent-field and configuration-interaction methods,” in: L. P. Kayushin, M. K. Pulatova, and K. M. L'vov, Investigation of Paramagnetic Centers in Irradiated Enzymes [in Russian], Chapter 6, Nauka, Moscow, 1969.Google Scholar
  14. 14.
    V. I. Danilov, Yu. A. Kruglyak, and V. I. Pechenaya, TEKh [Theoretical and Experimental Chemistry], 5, 669, 1969.Google Scholar
  15. 15.
    V. I. Danilov et al., Theoret. Chim. Acta, 13, 288, 1969.Google Scholar
  16. 16.
    L. Clark and I. Tinoco, J. Amer. Chem. Soc., 87, 11, 1965.Google Scholar
  17. 17.
    V. Kleinwachter et al., Photochem. Photobiol., 5, 579, 1966.Google Scholar
  18. 18.
    J. W. Longworth et al., J. Chem. Phys., 45, 2930, 1966.Google Scholar
  19. 19.
    A. N. Terenin, Photochemistry of Dyes and Related Organic Compounds [in Russian], Izd-vo AN SSSR, Moscow, 1947.Google Scholar
  20. 20.
    R. O. Rahn et al., J. Chem. Phys., 45, 2955, 1966.Google Scholar
  21. 21.
    A. Wacker, in: Progress in Nucleic Acid Research, Vol. 1, Acad. Press, New York, p. 369, 1963.Google Scholar

Copyright information

© Consultants Bureau 1972

Authors and Affiliations

  • Yu. A. Kruglyak
    • 1
    • 2
  • V. I. Danilov
    • 1
    • 2
  • V. A. Kuprievich
    • 1
    • 2
  • V. V. Ogloblin
    • 1
    • 2
  1. 1.Pisarzhevskii Institute of Physical ChemistryAS UkrSSRUSSR
  2. 2.Institute of Microbiology and VirusologyAS UkrSSRKiev

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