Synthesis, growth and characterization of new organic crystal: 2-Aminopyridinium p-Toluenesulfonate for third order nonlinear optical applications

2-Aminopyridinium p-Toluenesulfonate (2APPTS), an organic NLO crystal, was grown for the first time by the slow evaporation solution technique. Single crystal X-ray diffraction analysis reveals that 2APPTS belongs to monoclinic crystal system with centrosymmetric space group P21/n. The determined lattice parameters are a=8.580(7) Å, b=6.419(5) Å, c=23.277(18) Å, β=100.016(3)° and volume=1262.58(3) Å3. Powder XRD study reveals the crystalline nature of the grown sample. FT-IR and FT-Raman studies were carried out to identify the functional groups present in 2APPTS. FT-NMR spectral study confirms the number of protons and carbon present in the molecular structure of the title compound. Thermal behavior and stability of 2APPTS were investigated by thermogravimetric (TG) and differential thermal analyses (DTA). Transparency of the title crystal in UV-vis-NIR region was analyzed and the optical band gap energy was found to be 3.6 eV. The mechanical properties of the grown crystals have been analyzed by the Vickers microhardness method. The etching studies reveal the growth pattern and dislocations present in the grown 2APPTS crystal. The negative third order nonlinear optical parameters like refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) were estimated by Z-scan studies.