Substituent effects on radical cations of halogenated biphenyl compounds: A density functional theory and time-resolved resonance Raman study

Abstract

We report density functional theory calculations to obtain the optimized structures for the ground state neutral molecule and radical cations for twelve substituted biphenyl compounds. We have also obtained experimental Raman spectra of the ground state neutral molecule and radical cations for several substituted biphenyl compounds. We investigate how the type of halogen atom (fluoro, chloro, or bromo) and its substitution position influences the structure and properties of the radical cations of halogenated biphenyl compounds. All of the halogenated biphenyl compounds have non-planar radical cations with the degree of planarity increasing for ortho substituted halobiphenyls compared to meta and para substitution due mainly to steric interactions. Multiple ortho substitution increases the degree of non-planarity of the radical cation.