Electronically excited states of protonated phenol and para-substituted phenol

Abstract

The low-lying electronic excited states of protonated phenol and para-Fluorophenol have been investigated extensively by RI-MP2/RI-CC2 methods. Although, protonation of phenol leads to a small red-shift-effect on the S 1-S0 (ππ) electronic transition in respect to its neutral homologue, a large red-shift-effect, on the same electronic transitions of para-substituted phenol has been predicted. The ππ excited state of protonated phenol stays in the UV range (4.34 eV), while its πσ state lies in the VUV region (8.3 eV). The S1 excited-state geometry optimization of protonated phenol predicted unstable S1 state owing to the strong out-of-plane deformation in the benzene ring. © 2012 Elsevier B.V. All rights reserved.