Synthesis, crystal structure and vibrational spectroscopy of a nonlinear optical crystal: l-arginine maleate dihydrate

From the aqueous solution containing l-arginine and maleic acid (C4H4O4), crystals of l-arginine maleate dihydrate were grown. The crystal structure was determined by single crystal X-ray diffraction. In the triclinic unit cell (space group P1), the molecule contains one l-arginine cation, one maleate anion and two water molecules. The crystal can be described as an inclusion complex from its layer structure. The basic unit in l-arginine layer is centrosymmetric and the maleate anions exist in coplanarity. Hydrogen bond plays a great role in the construction of the crystal and nonlinear optical properties. The crystal was characterized by infrared (IR) and Raman spectra. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder second harmonic generation (SHG) experiment was investigated to explore its NLO properties.