Spectral features of formation of H-bonded complexes in coumarins and psoralens

Abstract

Spectral features of H-bonded complexes formed by molecules of coumarin 1 and psoralen with methanol (1∶1) have been studied by the methods of quantum chemistry [a semiempirical method with intermediate neglect of differential overlap (INDO) with special spectroscopic parametrization] and by the method of electrostatic potential (MEP). The MEP using INDO wave functions was used to find ways of approach to the methanol molecules and the structure of H-bonded complexes. The direction of spectral shifts of the different (with respect to the orbital nature) electronic excited states in the formation of the complexes and ways of approach to the solvent molecules in the formation of the first solvation shell are established.