Enol-keto swching Schif base ligand Salicylidenemethyl Furylamine

Potential energy surfaces (PES) for the ground and excited state intramolecular proton transfer (ESIPT) processes in N- salicilydenemethylfurylamine (SMFA) have been studied using CC2 level of theory. Our calculations suggest the non- viability of ground state intramolecular proton transfer. Excited states PES calculations support the existence of ESIPT process in SMFA. The calculated results show that the intramolecular hydrogen bond were formed in the S0 state, and upon excitation, the intramolecular hydrogen bonds between - OH group and nitrogen atom would be strengthened in the S1 state, which can facilitate the proton transfer process effectively. The minimum energetic level of the S1 state along the PT coordinate lies in the short distance to the long distance of OH, which corresponds to the new bond formation of H−N. A barrierless reaction path directs the system back to the enol- type minimum of the S0 potential energy surface. According to calculation results, a trans-keto type structure obtained from photoexcitation of the enol, can be responsible for the photochromoic effect, thus closing the photocycle of title compound.