Structural and solid state properties of l-leucinium p-toluenesulfonate monohydrate: an amino acid tosylate NLO crystal

Abstract

An amino acid tosylate NLO crystal, l-leucinium p-toluenesulfonate monohydrate (LLPT) was synthesized and single crystal was grown by slow evaporation solution growth technique. The single crystal XRD study was employed to evaluate the structural properties and found good agreement with the reported values. The compound crystallized in the non-centrosymmetric orthorhombic cell setting with P2₁2₁2₁ space group. The crystal packing is dominated by N–H···O and O–H···O hydrogen bonds leading to number of chain and ring motifs. These motifs are arranged in tandem along ab-plane of the crystal leading to alternate hydrophilic and hydrophobic layers along c-axis of the unit cell. Vibrational spectral measurements (FTIR and FT-Raman) shows the different functional groups and strength of the hydrogen bonds. The optical cutoff wavelength and absorbance studies of the compound have been examined by UV–Vis–NIR absorbance spectrum. The material did not show any significance absorption in the entire visible region and cutoff wavelength at 283 nm. The emission property of the material was analyzed by Photoluminescence study and the material has ultraviolet emission. TGA/DTA studies show that the material became anhydrous around 73 °C and start melting at 169 °C. Vicker’s microhardness test show that LLPT belongs to soft category material. The dielectric behaviour and solid state parameters of the compound were analyzed at room temperature by dielectric studies with varying frequency. Kurtz and Perry SHG tests confirms the materials ability to green emission when exposed to a laser with wavelength of 1064 nm and the SHG efficiency of 0.5 times the KDP.