Conformational potential energy curves for low lying excited states of selected polyfluorobiphenyl (PFB) and polychlorobiphenyl (PCB) congeners

Ting Hua Tang, M. Nowakowska, J. E. Guillet, I. G. Csizmadia

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The geometrical, conformational and energy changes associated with electronic excitation to low lying triplet (T1) and singlet (S1) states were investigated for polyfluorobiphenyls and polychlorobiphenyls. In the case of the lowest triplet state (T1) noticeable double bond character between the two rings that is diagnostic of the p,p' -diradicaloid structure {A figure is presented} for both the parent biphenyl and its polyhalogenated forms was observed. Furthermore, the two rings lost their planarity for the 2,2 ',-3,3 '-6,6 '-hexahalobiphenyls upon excitation, which was not the case for the other congeners that had no ortho halogen in the two benzene rings. Hexahalobiphenyls also showed potential curve topologies that were different for the S0 and T1 states from those of the dihalo and tetrahalo congeners, indicating that ortho substitution does make a difference. The excitation energies for the hexahalo congeners with four ortho substituants were markedly different from the excitation energies for the dihalogenated and tetrahalogenated biphenyls in which no halogen was present in the ortho position.

Original languageEnglish
Pages (from-to)147-164
Number of pages18
JournalJournal of Molecular Structure: THEOCHEM
Volume233
Issue numberC
DOIs
Publication statusPublished - Sep 6 1991

ASJC Scopus subject areas

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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