Synergistically improving myricetin ESIPT and antioxidant activity via dexterously trimming atomic electronegativity

Abstract The development of diagnostic and therapeutic drugs for superoxide ions in organisms is extraordinarily vital in the field of biomedical. Herein, we tuned the electronegativity of the atoms (O, S, Se) to study their effect on the excited state intramolecular proton transfer (ESIPT) and antioxidant activity of myricetin (MYR) by density functional theory (DFT) and time-dependent DFT methods. The study revealed that the reduction of atomic electronegativity effectively diminishes the barrier of ESIPT. The reduced potential barrier allows MYR derivatives to have stronger K* state fluorescence compared with the original MYR. By calculating the fluorescence spectra of MYR and its derivatives, the derivatives of MYR exhibit a more reddish K* state photoluminescence. Moreover, the antioxidant activity of MYR derivatives tends to increase as the electronegativity of atoms decreases. Interestingly, the K state antioxidant activity of the three studied molecules is stronger than its own E state. Furthermore, this phenomenon is largely pronounced in the derivatives of MYR. The frontier molecular orbitals, non-covalent interactions, infrared spectra, electronic spectra, potential energy curves, antioxidant activities have cross-validated our results. Our work will provide support for the design and development of a more outstanding diagnosis and treatment drugs in organisms.