Molecular and electronic structures of bipolaron in poly-para-phenylene in terms of molecular orbital symmetry

Akira Imamura, Yuuichi Orimoto, Yuriko Aoki

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The molecular structures of the model systems of the polaron and the bipolaren in poly-paraphenylene (PPP) were calculated by an ab initio molecular orbital (MO) method with fairly sophisticated approximations. The calculated models are monocations, dications, monoanions and dianions of biphenyl, para-terphenyl, para-quaterphenyl, para-quinquephenyl and para-hexaphenyl. The calculations show that the longer the PPP oligomer is, the stronger is the tendency to take on a non-planar twisting structure. This was accounted for by the combination of repulsions between proximate ortho-hydrogen atoms with resonance interactions between benzene π MOs. The magnitude of the resonance interactions was assessed by using the symmetry of benzene π MOs as well as an analytical Hückel solution of the π MO for polyene. In addition, negatively charged polarons and bipolarons were found to have a stronger tendency to take on a planar structure than positively charged ones. This result was also explained by comparing the benzene π HOMO with the benzene π LUMO.

Original languageEnglish
Pages (from-to)180-187
Number of pages8
JournalTheoretical Chemistry Accounts
Volume102
Issue number1-6
DOIs
Publication statusPublished - Jun 1999

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

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