Theoretical study of solvent influence on the electronic absorption and emission spectra of kynurenine

Enrico Benassi, Peter S. Sherin

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4 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)3799-3804
Number of pages6
JournalInternational Journal of Quantum Chemistry
Volume111
Issue number14
DOIs
Publication statusPublished - 15 Nov 2011
Externally publishedYes

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Keywords

  • absorption and emission spectra
  • CS-INDO/CI
  • DFT calculations
  • kynurenine
  • PCM model
  • proximity effect

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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