Russian Chemical Bulletin

, Volume 44, Issue 12, pp 2261–2264 | Cite as

AM1 study of photoelectronic spectra

8. Direct calculations of ionization in the study of conformations of some methoxy-substituted benzenes
  • A. I. Vokin
  • V. K. Turchaninov
Physical Chemistry


Ionization energies of four model compounds with known conformations,i.e., benzo-1,3-dioxole, 2-methoxyphenol, benzo-1,3-dioxole-5-carbaldehyde (piperonal), and 4-hydroxy-3-methoxybenzaldehyde, have been calculated by theab initio AM1 method, using the formalized scheme of configuration interactions. It has been demonstrated that this method is adequate for the study of photoelectronic spectra of methoxy(hydroxy)-substituted benzenes. The ionization energies of 1,2-dimethoxybenzene, 3,4-dimethoxybenzaldehyde, and 4-hydroxy-3,5-dimethoxybenzaldehyde have been calculated for various orientations of theo-methoxy(hydroxy) groups. It has been revealed that three first ionization potentials corresponding to the states with vacancies on the π-MO depend on the torsion angle. It has been established by comparison of calculated and experimental ionization potentials that in gas the compounds with adjacent methoxy groups have one O-Me bond parallel with the plane of the benzene ring, while another group is nearly perpendicular to this plane. Conformations of the heavy-atom framework are planar for gaseous molecules with adjacent methoxy and hydroxy groups.

Key words

molecular conformation photoelectronic spectroscopy ab initio quantum-chemical calculations methoxy(hydroxy)-substituted benzenes and benzaldehydes 


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Copyright information

© Plenum Publishing Corporation 1996

Authors and Affiliations

  • A. I. Vokin
    • 1
  • V. K. Turchaninov
    • 1
  1. 1.Irkutsk Institute of Organic ChemistrySiberian Branch of the Russian Academy of SciencesIrkutskRussian Federation

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