Growth and combined experimental and quantum chemical study of glycyl-L-Valine crystal

Glycyl-L-Valine (GLV) crystals were grown using distilled water as the solvent at room temperature by solution growth technique. Powder X-ray diffraction confirms the crystalline quality of GLV crystal. The molecular structure of GLV crystal was identified by ¹³C NMR spectral studies. The nonlinear optical (NLO) behavior of the crystal was found to be ∼4.3 times greater than that of potassium dihydrogen orthophosphate. FT-Raman and FT-IR spectra of the GLV were recorded and complete functional group assignment of the determined vibrational bands of GLV have been reported. Density functional theoretical method (DFT) was performed using B3LYP with the 6-311+G (d, p) basis set and the results were compared with the experimental values which confirm the intermolecular interactions responsible for the enhanced NLO activity of the molecule, as evident from NBO and Hirshfeld analyses. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. In addition, the molecular electrostatic potential (MEP) analysis, Mulliken atomic charges of the GLV molecule has been investigated using theoretical calculations.