Theoretical and Experimental Chemistry

, Volume 26, Issue 2, pp 155–160 | Cite as

Proton phototransfer performance for 2-heteryloxazoles

  • S. I. Druzhinin
  • I. V. Troyanovskii
  • S. A. Krashakov
  • B. M. Uzhinov
Article
  • 15 Downloads

Abstract

Fluorescence spectroscopy has been applied to the photopyrolytic reactions of 2-hetaryloxazoles with acetic acid in ethanol. The reactions occur in the excited state via static and dynamic mechanisms. Various 4-substituted pyridines have similar acid-base parameters in the ground and excited states, which agrees with CNDO/S calculations. The quantum yields, equilibrium constants, and rate constants for these reactions have been determined. The performance factors in proton phototransfer for the 2-hetaryloxazoles are close to one and at least 2.4 times larger than for aza derivatives of aromatic hydrocarbons. The photoreaction and the deactivation induced by it probably involve the same reaction center: the nitrogen atom in the six-membered heterocyclic. A principle of minimum photochemical motion is proposed, in which the quantum performance in the formation of the excited products is inversely related to the change in the system wave function during the reaction. The measurements agree qualitatively with this principle.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Literature cited

  1. 1.
    A. B. Dymyashkevich, B. M. Uzhinov, and M. G. Kuz'min, “Proton phototransfer and radiationless electronic-excitation energy degradation in systems formed by azaphenanthrenes with organic acids,” Khim. Vys. Energ.,12, No. 2, 142–147 (1978).Google Scholar
  2. 2.
    A. I. Galeeva, R. T. Kuznetsova, and R. M. Fofonova, “An experimental and quantum-chemical study on the luminescence spectra of 2-(4-pyridyl)-5-phenyloxazole PyPO,” in: Abstracts of the All-Union Conference on Organic Luminophors and Their Economic Applications, Kharkov, December 5–7, 1984 [in Russian], Kharkov (1984), p. 40.Google Scholar
  3. 3.
    N. Ya. Vasil'eva and I. V. Sokolova, “Effects from isomerism and the solvent on proton phototransfer in the quinoline analogs of the phenyloxazoles,” in: Abstracts for the Fifth All-Union Conference on Photochemistry, Suzdal', February 19–21, 1985 [in Russian], Moscow (1985), Part 1, p. 177.Google Scholar
  4. 4.
    V. L. Shapovalov, A. B. Demyashkevich, and M. G. Kuz'min, “Static and dynamic proton phototransfer mechanisms in the system formed by 1-azaphenanthrene with acetic acid in an aliphatic alcohol,” Zh. Prikl. Spektr.,33, No. 6, 1111–1116 (1980).Google Scholar
  5. 5.
    Yu. A. Ustynyuk (editor), Quantum-Chemical Methods for Molecules [in Russian], khimiya, Moscow (1980).Google Scholar
  6. 6.
    B. M. Uzhinov, S. I. Druzhinin, and G. M. Rodchenkov, “Oxazole photoprotylitic reactions,” in: Abstracts for the Fifth All-Union Conference on Photochemistry, Suzdal', February 19–21, 1985 [in Russian], Moscow (1985), Part 1, p. 102.Google Scholar
  7. 7.
    S. I. Druzhinin and V. M. Uzhinov, “The mechanism of fluorescence quenching of aromatic compounds by acids: ZDO calculations,” Chem. Phys.,78, No. 1, 29–39 (1983).Google Scholar
  8. 8.
    H. C. Longuet-Higgins, “Some studies in molecular orbital theory. 2. Ionization constant in heteroaromatic amines and related compounds,” J. Chem. Phys.,18, No. 3, 275–282 (1950).Google Scholar
  9. 9.
    V. L. Shapovalov, Electronic-Excitation Energy Degradation in Proton Phototransfer in Hydrogen-Bonded Complexes: Ph.D. Thesis [in Russian], Moscow (1984).Google Scholar
  10. 10.
    V. G. Plotnikov and G. V. Maier, “Internal conversion initiated by photochemical reactions,” Opt. Spektrosk.,47, No. 1, 113–120 (1979).Google Scholar
  11. 11.
    N. G. Bakhshiev, Introduction to Molecular Spectroscopy [in Russian], Izd. Leningrad. Universiteta, Leningrad (1974).Google Scholar
  12. 12.
    Yamaguchi, T. Ikeda, and H. Mametsuka, “Electronic structures of excited states of benzoquinolines,” Bull. Chem. Soc. Jpn.,48, No. 4, 1118–1122 (1975).Google Scholar
  13. 13.
    F. O. Rice and O. Teller, “The role of free radicals in elementary organic reactions,” J. Chem. Phys.,6, No. 8, 489–496 (1938).Google Scholar
  14. 14.
    C. Trindle, “Analysis of matched reactions by mapping,” Usp. Khim.,40, No. 11, 2102–2118 (1971).Google Scholar

Copyright information

© Plenum Publishing Corporation 1990

Authors and Affiliations

  • S. I. Druzhinin
    • 1
  • I. V. Troyanovskii
    • 1
  • S. A. Krashakov
    • 1
  • B. M. Uzhinov
    • 1
  1. 1.Moscow UniversityUSSR

Personalised recommendations