A comprehensive evaluation of nonlinear optical materials: Synthesis, growth, spectral, photoluminescence, LDT, photoconductivity, thermal, antibacterial and second harmonic generation analysis

The low-temperature solution technique is an effective method for growing high-quality single crystals, such as Bis(D-phenylglycinium) sulfate monohydrate. This exceptional compound unequivocally crystallises within the monoclinic space group P2₁, as demonstrated by X-ray diffraction analysis. FT-IR and FT-Raman spectroscopy confirmed the presence of various functional groups and their corresponding vibrational modes. FT-NMR analyses verified the presence of hydrogen and carbon atoms in the synthesised material. The optical properties of the compound were characterised by the UV–Visible absorption spectrum, which revealed a cut-off wavelength of 230 nm and indicated a bandgap of 5.4 eV, suggesting superior optical quality for potential applications. The material's low Urbach energy implies minimal impurities, while photoluminescence testing revealed an extraordinary violet emission, a characteristic that underscores its suitability for NLO applications. HR-SEM and EDAX provided insightful images, illuminating the sample's surface structure, intricate morphology, and precise elemental composition with remarkable clarity and resolution. With an impressive laser damage threshold of 10.7 GW/cm², this material exhibits a notable resilience compared to its counterparts. Thermogravimetric analysis revealed a melting point of 273 °C, indicating commendable thermal stability. Investigations into the photoconductivity of the material revealed its positive photoconductive behaviour, a crucial trait for advanced applications. Remarkably, this compound has demonstrated significant antibacterial efficacy against gram-negative bacteria, and its SHG efficiency measured at 1.3 times that of the standard KDP, accentuates its promising potential in the fields of photonics and pharmaceutical chemistry.