Synthesis and antioxidant activity of gallic acid based fluorescent benzothiazole analogue: Photophysical, electrochemical, conceptual DFT, QTAIM and docking investigations

Abstract

The present investigation reports on the synthesis of a novel 3,4,5-trihydroxy-N-(6‑methoxy benzo[d]thiazol-2-yl)benzamide (TMTB) molecule and employs elemental analysis, 1H NMR, 13C NMR, and mass spectrum methods to determine the structure of the desired product. The experimental and theoretical absorption and emission spectra of the molecules are used to study the photophysical properties of the TMTB molecule. We investigate the in vitro antioxidant activity of TMTB using DPPH and superoxide radical scavenging assays, as well as molecular docking experiments with the target NAD(P)H oxidase (PDB ID: 2CDU) protein. To ascertain the energies of the LUMO and HOMO levels, NLO behaviour, intermolecular charge transport facilitated by global chemical reactivity descriptors, molecular electrostatic potentials (MEP), and hyperpolarizability analyses, an investigation was carried out on their conceptual DFT and QTAIM analyses operating under B3LYP/6–31 G. The simulated DFT calculation shows that TMTB is highly polarizable in both the gas and solvent phases, with HOMO-LUMO energy gaps of 4.18 and 4.24 eV, respectively. Total first and second hyperpolarizability values for TMTB in the gas phase were determined to be 155.09 × 10–30 and 3611.59 × 10–36 esu, respectively, whereas in the DMSO phase the values were 556.15 × 10–30 and 6223.79 × 10–36 esu. Computational studies results corroborate the experimental findings. Based on the photophysical and computational findings, the newly reported TMTB molecule was determined to be a promising candidate for additional optimization and use in optoelectronic devices.