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Substituent Effects in the Absorption Spectra of Phenol Radical Species: Origin of the Redshift Caused by 3,5‐Dimethoxyl Substitution
Author(s) -
Zhang Lei,
Muchall Heidi M.,
Peslherbe Gilles H.
Publication year - 2013
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12028
Subject(s) - chemistry , radical , phenol , absorption spectroscopy , photochemistry , substituent , density functional theory , complete active space , spectral line , absorption (acoustics) , ground state , perturbation theory (quantum mechanics) , computational chemistry , basis set , atomic physics , stereochemistry , physics , organic chemistry , optics , quantum mechanics , astronomy
The ground‐state equilibrium geometries, electronic structures and vertical excitation energies of methyl‐ and methoxyl‐substituted phenol radical cations and phenoxyl radicals have been investigated using time‐dependent density‐functional theory (namely TD ‐B3 LYP ) and complete‐active‐space second‐order perturbation theory ( CASPT 2). The “anomalous” large redshifts of the absorption maxima of the phenol radical species observed in the ultraviolet–visible spectral region upon di‐ meta ‐methoxyl substitution are reproduced by the calculations. Furthermore, these “anomalous” shifts which were unexplained to date can be rationalized on the basis of a qualitative molecular orbital perturbation analysis.