Multifaceted exploration of p-toluic acid single crystals: Structure, optics and nonlinear photonic potential

This research explores the structural, optical, mechanical and nonlinear optical (NLO) properties of p-toluic acid single crystals obtained by slow evaporation. SXRD and PXRD ascertained phase purity, FTIR determined functional groups, and UV–Visible spectroscopy ascertained transparency and band gap. SEM, LDT, contact angle, chemical etching and microhardness tests evaluated morphology, stability, wettability, defects and strength. Z-scan measurements established third-order susceptibility and nonlinear refractive index. Hirshfeld and 2D fingerprint investigations revealed [Formula: see text] (38.9%), [Formula: see text]/[Formula: see text] (31.8%) and [Formula: see text] (8.5%) contacts, i.e., hydrogen bonding and [Formula: see text]–[Formula: see text] stacking. Energy framework calculations presented major dispersion forces ([Formula: see text] [Formula: see text]kJ/mol at 3.62[Formula: see text]Å) supplemented by electrostatics and polarization effects, improving mechanical strength and NLO activity.