TRIPQUARTET AND SEXTET LUMINESCENCE FROM CHROMIUM PORPHYRINS
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Date
1974
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
We have examined a Cr(III) octaethylporphin and a Cr(III) tetra-phenylporphin at temperatures ranging between $4^{\circ} K$ and $300^{\circ} K$. Both species exhibit abnormal absorption and emission spectra. The room temperature absorption spectra contain extra bands in the uv and near ir. The weak red shifted luminescence shows marked temperature dependence of quantum yields, band profiles, and lifetimes. We explain the electronic spectra by a model in which three unpaired d electrons on the chromium are coupled with the porphyrin $\pi$ levels. All singlet states become quartets and the triplet states split into doublets, ``tripquartets”, and sextets. The emission properties are believed to result from tripquartet and sextet states in thermal equilibrium. The nature of the porphyrin ring substituents appears to affect the tripquartet-sextet energy gap.
Description
Present address of Louise Karle Hanson: Laboratory of Chemical Physics, National Institute of Arthritis, Metabolism and Digestive Diseases, National Institutes of Health, Bethesda, Maryland, 20014. Present address of Gamal-Eddin Khali1: Department of Chemistry, Florida State University, Tallahassee, Florida, 32306.
Author Institution: Department of Chemistry, University of Washington
Author Institution: Department of Chemistry, University of Washington