Designing Diaryl Sulfide Electronic Properties: A Comprehensive DFT Guide to HOMO-LUMO Gaps and Reactivity...

Diaryl sulfides, characterized by a sulfur atom bonded to two aryl groups, exhibit distinctive electronic properties arising from the interplay between the delocalized π-system of the aromatics and the lone pairs on sulfur. We report the first comprehensive computational study of 12 diaryl sulfide (DS12) derivatives using nine density functional theory (DFT) functionals. Their geometric parameters (bond distances, angles, and torsion angles), dipole moments, vertical transition energies, and thermochemical properties (ionization potentials and electron affinities) were computed. In the absence of experimental data, the DFT results were benchmarked against high-level DLPNO-CCSD-(T)/cc-pVTZ calculations. The analysis reveals that molecule 8 is the most stable (HOMO-LUMO gap = 4.358 eV), whereas molecule 1 exhibits the highest electrophilicity (6.931 eV). For dipole moment calculations, B1LYP emerges as the most accurate functional (MAE = 0.246 D), closely followed by B3LYP (MAE = 0.262 D). In contrast, the TPSSh (MAE ≈ 0.20 eV) and B3PW91 (MAE ≈ 0.17 eV) functionals are recommended for exploratory studies requiring reliable vertical transition energies.