Synthesis, growth and characterization of a new hydrogen bonded organic tosylate crystal: l-alaninium p-toluenesulfonate for second order nonlinear optical applications

An organic hydrogen bonded NLO material, l-alaninium p-toluenesulfonate (LAPT), was successfully synthesized and crystallized by slow evaporation solution growth technique with the dimension of 40 × 27 × 3 mm³. The crystal and molecular structures of LAPT were elucidated by single crystal X-ray diffraction technique. It reveals that the compound crystallized in a non-centrosymmetric orthorhombic space group P2₁2₁2₁. The crystal packing features intricate three dimensional hydrogen bonding network which are observed at z = 1/4 and 3/4 and aromatic rings of the anions are stacked at x = 0 and 1/2. The molecular structure of the compound and its vibrational behaviour were analyzed by FTIR and FT-RAMAN spectral studies. UV–Vis–NIR spectral study revealed that the LAPT crystal has a wide transmission window in the entire visible region with the lower cutoff wavelength 282 nm. The luminescence study showed an ultraviolet emission of LAPT compound. TGA/DTA revealed the thermal stability of LAPT compound. The mechanical property of the title compound was analyzed by Vicker’s hardness test. The dielectric constant and dielectric loss of the crystal were measured as function of frequency at room temperature, and the results are discussed. The nonlinear optical property was confirmed by the Kurtz Perry powder technique and it was found to be two times higher than the pure potassium dihydrogen phosphate.