Theoretical revealing regulated ESIPT behaviors by atomic electronegativity for quercetin fluorophore

We mainly focus on exploring atomic electronegativity dependent photo-induced behaviors of quercetin derivatives (Que-O, Que-S and Que-Se). For distinguishing the effects of two intramolecular hydrogen bonds (O1-H2···O3 and O5-H4···O3), we firstly predict O5-H4···O3 is more strengthening than the O1-H2···O3 one in S1. Photo-induced charge recombination and energy gaps of frontier molecular orbitals reveals intramolecular charge transfer promotes ESIPT behavior. By constructing potential energy curves (PECs) and searching transition state (TS) forms, we clarify the ESIPT behavior of quercetin related to atomic electronegativity. We find decreasing atomic electronegativity (O → S → Se) could promote ESIPT reaction.