Modulating mechanism of NH-based excited-state intramolecular proton transfer by electron-withdrawing substituent at aromatic para-position

Abstract Using TDDFT method, modulating mechanism of N H-based excited-state intramolecular proton transfer by electron-withdrawing substituent cyano at the aromatic para-position of four 2-(2′-aminophenyl) benzothiazole compounds have been demonstrated at B3LYP/6-311+G(d, p)/IEFPCM theory level. The scanned potential energy curves reveal that introduction of a strong electron-withdrawing group tosyl at the amino nitrogen can remarkably facilitate the occurrence of the ESIPT reaction, whereas introduction of a weak electron-withdrawing group acetyl at the amino nitrogen or introduction of an electron-withdrawing cyano group on the benzene ring at the para-position with respect to the amino group can contribute to the ESIPT process in certain degree.