l-Phenylalanine l-phenylalaninium bromide – a new nonlinear optical material

Abstract

L-Phenylalanine L-phenylalaninium bromide (LPLPB), an amino acid non-centrosymmetric crystal having a large second harmonic generation (SHG) efficiency, being 4.5 times that of KH₂PO₄ (KDP), has been successfully grown using a slow evaporation method employing a temperature gradient technique. The structure of the grown crystal was solved and refined by single-crystal X-ray diffraction, and this demonstrates that it belongs to a monoclinic system with the space group P2₁. The confirmation of its functional groups was recorded using Fourier transform infrared spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study its thermal properties. The optical behaviour was examined and its optical constants were determined by UV-vis analysis. Dielectric spectroscopy reveals the dielectric nature of the grown crystal. The mechanical strength of the grown LPLPB was estimated by microhardness studies, and the Young's modulus of the grown LPLPB was calculated to be 3.310 × 10¹⁰ N m⁻².