Unveiling the hidden potential of gallic acid: A multifaceted study of its physical and optical properties

With an eye toward its nonlinear optical (NLO) properties, this paper investigates the slow evaporation solution growth technique for generating fully formed organic gallic acid (GA) crystals. Single-crystal X-ray diffraction (SXRD) was utilized to study the structural characteristics, while powder X-ray diffraction (PXRD) confirmed the crystalline phase. FTIR spectroscopy found functional groups and chemical vibrations. The optical bandgap was measured and optical characteristics, including transparency in the 200–1200[Formula: see text]nm wavelength range, were investigated using UV–Vis spectroscopy. Energy dispersive X-ray (EDX) spectroscopy was used to assess the elemental composition of GA crystals; scanning electron microscopy (SEM) was used to analyze their morphology. Using thermogravimetric (TG) analysis and differential scanning calorimetry (DSC), thermal stability and degradation behavior were investigated, thereby uncovering notable transitions including gradual thermal deterioration, melting, and moisture loss. To improve understanding of the crystal formation process, theoretical models were used to calculate the nucleation parameters and controlled nucleation rate. A detailed characterization confirms the potential of GA crystals for NLO applications. The observed third-order NLO response of GA crystals is attributed to the synergistic effects of [Formula: see text]-electron delocalization, hydrogen-bonded networks, and donor–acceptor charge transfer interactions. These interactions enhance molecular polarizability, leading to a negative nonlinear refractive index (self-defocusing) and high third-order susceptibility. Such features demonstrate the suitability of GA crystals for advanced nonlinear photonic applications.