Dications of bis-triarylamino-[2.2]paracyclophanes: Evaluation of excited state couplings by GMH analysis |
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Authors: | Amthor Stephan Lambert Christoph |
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Institution: | Institut für Organische Chemie, Universit?t Würzburg, Am Hubland, D-97074 Würzburg, Germany. |
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Abstract: | In this paper, we present the absorption properties of a series of bis-triarylamino-2.2]paracyclophane diradical dications. The localized pi-pi and the charge-transfer (CT) transitions of these dications are explained and analyzed by an exciton coupling model that also considers the photophysical properties of the "monomeric" triarylamine radical cations. Together with AM1-CISD-calculated transition moments, experimental transition moments and transition energies of the bis-triarylamine dications were used to calculate electronic couplings by a generalized Mulliken-Hush (GMH) approach. These couplings are a measure for interactions of the excited mixed-valence CT states. The modification of the diabatic states reveals similarities of the GMH three-level model and the exciton coupling model. Comparison of the two models shows that the transition moment between the excited mixed-valence states mu(ab) of the dimer equals the dipole moment difference Delta of the ground and the excited bridge state of the corresponding monomer. |
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