Theoretical studies of transannular interactions. I. Benzene excimer fluorescence and the singlet states of the paracyclophanes

Martin T. Vala*, Ian H. Hillier, Stuart A. Rice, Joshua Jortner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The changes in the electronic transition energies of benzene which occur on dimerization have been calculated. It is shown that the energy-level splittings due to the interactions between neutral-excitation states are too small to explain the observed anomalous emission from concentrated benzene solutions and the absorption spectra of the paracyclophanes. To extend the theory, the eight-electron problem is treated for configurationally interacting neutral-excitation and charge-resonance states. Intermolecular overlap is included in a way consistent with the use of a core potential in the Goeppert-Mayer-Sklar representation. Use is also made of Hückel LCAO molecular orbital wavefunctions and a linear combination of four Slater carbon-atom 2pπ wavefunctions fit to an SCF function. The anomalous emission from benzene solutions can now be understood to arise from transitions from the lowest excimer state of α-level parentage for benzene molecules ̃3 or ̃3.3 A apart when ground-state repulsion is taken into account. The solution absorption spectra of the paracyclophanes are interpreted within this framework of neutralexcitation-charge-resonance configuration interaction. Finally, dimer symmetries different from D6h, have been invesigated in an attempt to understand the absorption spectra of single crystals of [2.2] paracyclophane.

Original languageEnglish
Pages (from-to)23-35
Number of pages13
JournalThe Journal of Chemical Physics
Volume44
Issue number1
DOIs
StatePublished - 1966
Externally publishedYes

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