Photoswitching of SalicylidenemethylFurylamine: A Theoretical Photodynamics Study

Potential energy surfaces (PES) for the ground and excited state intramolecular proton transfer(ESIPT) processes in N-salicilydenemethylfurylamine(SMFA)have been studied usingCC2 level of theory. Ourcalculations suggest thenon-viability of ground state intramolecular proton transfer. Excited states PEScalculations support the existence ofESIPT process in SMFA.The calculated results show that theintramolecularhydrogen bond were formed in the S0 state, and upon excitation, theintramolecular hydrogen bonds between -OH group and nitrogen atomwould be strengthened in the S1 state, which can facilitate the proton transferprocesseffectively. The calculations indicate two S1/S0 conical intersections(CIs) which provide radiation-lessdecay to the ground state.At the CIs, twobarrier-free reaction coordinates direct the excited system to the groundstate of enol-type minimum.The keto-type S1 state attained by barrierless proton transfer is found to beunstablevia a torsional motion, which provides fast access to a S1−S0 conicalintersections. From the conicalintersection, a barrierless reaction path directs thesystem back to the enol-type minimum of the S0 potentialenergy surface, thus closingthe photocycle.

Keywords:

Schiff Base , Intramolecular Proton Transfer , Photochromism