Selenium-substituted conjugated small molecule: Synthesis, spectroscopic, computational studies, antioxidant activity, and molecular docking

In this study, a small molecule, 4-(7-(5 '-hexyl-[2,2 '-bithiophen]-5-yl)benzo[c][1,2,5]selenadiazol-4-yl)-N, N- diphenyl aniline (HST) employing selenium (Se) containing heterocyclic derivative as a central core unit in their molecular skeleton has been synthesized by Suzuki coupling reaction. The NMR, FT-IR, and mass spectroscopy techniques were used to evaluate the molecular structure of the HST molecule. The HST molecule displays excellent absorption properties in various protic and aprotic solvents in the 200-800 nm range. FT-IR, FT-Raman spectra, and geometric parameters are performed by DFT and TD-DFT methods with the B3LYP/6-311G (d,p) basis set, which is well compared to experimental results. Additionally, the CAM-B3LYP/6-311++G(d,p) basis set was also employed with the TD-DFT method for UV-vis spectrum calculations. Frontier molecular orbitals, UV-vis spectra, and global reactivity descriptors were made to reveal the solvent effect. It was also found that electronic properties correlate well with solvent polarity. The HST molecule exhibited magnificent antioxidant activity correlated with 2,2-diphenyl-1-picrylhydrazyl (DPPH). Furthermore, a molecular docking study explored HST interactions with Keap1 receptor, aiming to activate the body's antioxidant defense system. The analysis disclosed various interactions, resulting in a docking energy score of 10.3 kcal/mol.