Computational Investigation of Arylazo Sulfonates: Geometric, Electronic, and Nonlinear Optical Properties via TD ‐ DFT

In this study, the TD‐DFT method using the B3LYP functional (and CAM‐B3LYP for UV–Vis analysis) and the 6‐311+G(d,p) basis set was used to compute the optical reactivity of synthesized Arylazo Sulfonates ( 1a–1j ) compounds in the gas phase, the solvent phase‐ethanol, water, and acetonitrile medium. The geometric parameters, electronic structure, spectroscopic, and topological properties were determined and analyzed to elucidate the optical reactivity and charge‐transfer behavior of the compounds. The energy gap, global hardness, Mulliken charges, softness, and Fukui functions were assessed to forecast reactivity changes in the 1j compound in the gas phase, suggesting that electron promotion from HOMO to LUMO is more difficult, which has implications for biological activity and charge‐transfer processes. Also, the electronic properties, including MEP, Fukui functions, UV spectroscopy, ELF, NLO, and RDG of the title compounds were thoroughly investigated to establish a comprehensive reactivity profile. The MEP revealed greener zones indicate an electrostatic potential of the examined compounds that is nearly neutral, exhibiting neither severe electrophilicity nor nucleophilicity; however, this neutral electrostatic potential does not exclude the presence of localized reactive sites. Based on NLO analyses, the 1a compound has a first hyperpolarizability about 15.2 times greater than that of urea (0.373 × 10 −33 esu), demonstrating its high potential for nonlinear optical applications.