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Theoretical study of solvent influence on the electronic absorption and emission spectra of kynurenine
Author(s) -
Benassi Enrico,
Sherin Peter S.
Publication year - 2010
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22929
Subject(s) - chemistry , solvation , excited state , polarizable continuum model , solvent effects , solvent , density functional theory , absorption (acoustics) , absorption spectroscopy , emission spectrum , spectral line , atomic physics , photochemistry , computational chemistry , materials science , organic chemistry , physics , quantum mechanics , composite material
Neutral/zwitterionic form equilibrium, excited state wave functions, absorption and emission spectra of kynurenine (KN) in various solvents (water, methanol, ethanol, and dimethylsulfoxide) have been studied theoretically. The ground electronic state geometries have been optimized by density functional theory methods; the geometries of the first two singlets excited electronic states have been optimized using the CASSCF technique. The influence of the solvent was taken into account by the calculation of the solvation free energies using the Polarizable Continuum Model (PCM). The spectra of electronic absorption and fluorescence emission have been calculated by the CS‐INDO S‐CI and SDT‐CI methods [Momicchioli, Baraldi, and Bruni, Chem Phys, 1983, 82, 229]. The calculated data reproduce the experimental positions of maxima and the solvent‐induced shifts of the absorption and emission bands well. The energy gap between the two lowest excited states of KN increases from aprotic to protic solvents. This fact suggests that the “proximity effect” cannot be responsible for the ultrafast decay of KN fluorescence in protic solvents. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011