Fluorescence and Phosphorescence of Acetone in Neat Liquid and Aqueous Solution Studied by QM/MM and PCM Approaches

Electronic singlet and triplet n pi* absorption and emission energies of acetone in vacuum, neat liquid and aqueous solution have been calculated. Electronic states of acetone in solution have been modelled using combined molecular dynamics-quantum mechanics/molecular mechanics techniques and the polarizable continuum model. In addition, we have compared density functional theory based results to corresponding coupled cluster singles and doubles predictions. Theoretical results have also been compared to experimental data. In general, we have obtained a good description of solvent effects on the absorption energies. However, modelling of excited states explicitly is still a challenge for the applied approaches, as the solvent shifts of the singlet n pi* emission have been considerably underestimated and also the solvent shift related to the Stokes shifts of fluorescence was predicted to have incorrect sign compared to available experimental data. (C) 2010 Wiley Periodicals, Inc. Int J Quantum Chem 111: 1511-1520, 2011