The effect of hydrogen bonding interactions between 2-[4-(dimethylamino)phenyl]-3-hydroxy-4H-chromene-4-one in the ground and excited states and dimethylsulfoxide or methanol on electronic absorption and emission transitions

The absorption and fluorescence spectra of 2-[4-(dimethylamino)phenyl]-3-hydroxy-4H-chromene-4-one in benzene or toluene and in the presence of methanol (proton donor) or the highly polar dimethylsulfoxide (proton acceptor) were measured and analyzed from the point of view of the potential influence of hydrogen bonding interactions on the spectral characteristics. The changes in the positions of the spectral maxima were interpreted as a result of the formation of complexes between the title compound and specifically interacting molecules present in the system. The structure and properties of possible complexes were predicted at the PM3 (ground state) and PM3/CI (excited state) levels of theory. The unique spectral features of the compound investigated, to a large extent affected by intramolecular proton transfer in the excited state and by specific interactions with certain components in the medium, can be utilized to determine the properties of solutions. (C) 2004 Elsevier B.V. All rights reserved.