Study of intramolecular charge transfer of Michler's ketone using time dependent density functional theory

Intramolecular charge transfer of Michler's ketone (MK) in vacuum and in six different aprotic solvents has been studied by using time dependent density functional theory (TDDFT). Dynamic process and spectrum feature of a molecule is strongly influenced by the solvent-solute interactions. Therefore, in this work the explicit consideration of solvent-solute interaction has been taken in to account by using the polarizable continuum model (PCM). We have constructed the potential energy curve by taking a combination of two different types of torsional motion; first, an anti-twisting (similar to 23 degrees) of N,N-dimethylanilino group to bring back the pre-twisted molecule to a nearly planner geometry and second, a twisting (similar to 180 degrees) of N,N-dimethylamino moiety with respect to the phenyl ring (to which it is attached). A large bathochromic shift in our calculated emission and absorption energies for polar solvents is a clear reminiscent of charge transfer nature in the excited state. Finally, our results are in agreement with experimental findings and other available theoretical data. (C) 2008 Elsevier B.V. All rights reserved.