Charge-Transfer Complexes of Maleic Anhydride and Dichloromaleic Anhydride with Various Aromatic Compounds

Abstract

Abstract Absorption, fluorescence and fluorescence excitation spectra were measured at room temperature and at low temperature for charge-transfer complexes containing maleic anhydride and dichloromaleic anhydride as electron acceptors. Benzene, toluene, mesitylene, durene, hexamethylbenzene, aniline, dimethylaniline, naphthalene and anthracene were used as electron donors. The charge-transfer absorption and fluorescence bands were observed for these complexes, their peak positions being linearly dependent upon the ionization potentials of donors for the same electron acceptor. From the comparison of the charge-transfer absorption or fluorescence peaks of maleic anhydride complexes with the corresponding values of dichloromaleic anhydride complexes, the difference in electron affinity between these two electron acceptors was obtained to be 0.4 eV. The electronic structures of the maleic anhydride complexes with benzene, naphthalene and anthracene were studied theoretically by considering the configuration interaction among the ground, locally-excited and charge-transfer configurations. The stable geometrical configurations in the ground and lower excited states of the complexes were discussed by the aid of the energy levels calculated for various relative orientations between electron donor and acceptor.