Solvation of coumarin6 studied by vibrational spectroscopy and density functional theory

The optimized structure of coumarin6 has been obtained in different solvents using DFT and frequencies of vibration of some bands are observed to change in solvents. To understand the type of interactions taking place between coumari6, the Molecular Electric Potential (MEP) of the dye was plotted. The donor-acceptor and HOMO_LUMO analysis was also carried out and it was observed that interaction of solvent molecules is more favored at O atom of coumarin ring and of CO bonds as well as N, S atoms of the dye. In addition C-H bonds can also interact with solvent molecules through hydrogen bonding. These observations have been verified by obtaining optimized structures of stable complexes of coumarin6 with solvent molecules various positions mentioned above.