Theoretical Study On The Effect Of Hydrogen Bonding On Excited State Intramolecular Proton Transfer Of DEAHB Molecule

Excited state intramolecular proton transfer(ESIPT)is one of the important photophysical processes.Studying the mechanism of ESIPT is helpful to design and develop new functional luminescent materials and to help us understand important biological phenomena.In this paper,density functional theory(DFT)and time-dependent density functional theory(TDDFT)methods are carried out to investigate the influences of intramolecular and intermolecular hydrogen bonding on ESIPT for the 4-N,N′-(diethylamino)-2-hydroxybenzaldehyde(DEAHB).The structures of DEAHB and DEAHB-DMSO hydrogen bonded complex in the ground-state and the excited-state are optimized.We also calculated the vertical excitation energy of DEAHB monomer and DEAHB-DMSO complex in detail.In addition,the detailed descriptions of frontier molecular orbitals of DEAHB monomer and DEAHB-DMSO complex are presented.Moreover,the transition density matrix is worked out to facilitate deeper insight into the orbitals change.Besides,the comparative analyses of potential energy curve and infrared(IR)spectra between the ground-state and the excited-state have been carried out for DEAHB monomer.Our results show that DEAHB monomer occur ESIPT and the formation of intermolecular hydrogen bonding may restrain the ESIPT process of DEAHB monomer.