Synthesis, growth, structural and comprehensive analysis of a potential single crystal for third-order NLO applications: Experimental and theoretical insights

Semi-organic nonlinear optical single crystals are vital to current photonic technologies because they combine
the organic flexibility and inorganic stability. The third-order semi-organic NLO single crystal, -Phenyl
glycinium bromide (DPGBr), was successfully synthesised by slow evaporation from an aqueous solution. The
structural refinement of the crystal was elucidated with the SHELX-97, which concluded that it crystallises in the
orthorhombic system with space group P212121.Extensive structural, spectroscopic, optical, thermal, and
theoretical analyses were conducted. The molecular geometry has been optimised and is consistent with the
experimental data, validating the theoretical model. FT-IR and FT-Raman spectra are consistent with compu
tational vibrational frequencies, allowing functional group assignments. Optical properties were evaluated using
UV–visible-NIR and photoluminescence spectroscopy. The energy difference between HOMO and LUMO is 4.415
eV, indicating high stability in kinetic properties and charge transfer. The molecular electrostatic potential map
shows that intermolecular interactions influence both bromide and heteroatom sites, which exhibit large
negative potentials. The Hirshfeld surface analysis reveals that Van der Waals forces and hydrogen bonding affect
molecular packing. The material's hyperpolarizability (α0) demonstrates a strong NLO response. EDAX verified
the elemental composition, and thermal stability (TG-TA/DSC) testing showed it is stable up to 235◦surements of reverse saturable absorption with a nonlinear absorption coefficient of 0.48 × 10–10 C. Meam/W and an optical limiting threshold of 6.24 × 10 limiting applications. 12 W/m2 indicated that it is a promising material for photonic and optical limiting applications.