B. Proppe, M. Merchán, L. Serrano-Andrés
Feb 1, 2000
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Journal
Journal of Physical Chemistry A
Abstract
Ab initio results for the electronic spectra of 1-phenylpyrrole are presented. Vertical, emission, and nonvertical excitation energies have been computed using multiconfigurational second-order perturbation theory by means of the CASPT2 method. In the S0 and S1 states the most stable conformation was determined to be a twisted structure with a dihedral angle between the planes of the rings of 41.4° and 25.5°, respectively. The most intense feature of the absorption spectrum is predicted to be the S0 (11A) → S1 (21A) transition placed in vacuo at 5.07 eV. The lowest-excited state, S1 (11B), identified as the “locally excited” (LE) state, is calculated in vacuo to lie vertically 4.39 eV above the ground state, with the position of the 0-0 transition at 4.16 eV and a fluorescence maximum of 4.07 eV. An additional fluorescence feature is found at 3.72 eV in acetonitrile from a “twisted intramolecular charge transfer” (TICT) state in a perpendicular conformation. The absence of the low-energy emission in vacuo...