Photochemistry of maleimide

Abstract

The photoreaction of maleimide, one of the best model compounds of DNA molecules for psoralen-DNA photoreactions, is studied in order to investigate the photoreactivity and the mechanism of the maleimide-psoralen photoreaction. The reaction was carried out in organic solvents. The (2+2) photodimer of maleimide was obtained in the solution state by direct or sensitized irradiation. The rate constant is determined by quenching with biacetal. The value of the rate constant for reaction is found to be of the order of $10^9 sec^{-1}$. The direct dimerization of maleimide is found to proceed through the triplet excited state. The quantum yields of dimerization of maleimide are dependent on the maleimide concentration. The reaction products were analyzed by TLC and the major product was isolated by filtering the solid photoproducts followed by column chromatography. The structure of the photoadduct was determined by the physical methods.