Synthesis, crystal growth and characterization of an efficient nonlinear optical D-π-A type single crystal: 2-Aminopyridinium 4-nitrophenolate 4-nitrophenol

2-Aminopyridinium 4-nitrophenolate 4-nitrophenol (2APNP), with molecular formula C17H16N4O6 having D-π-A type, has been synthesized. Single crystals 2APNP were grown by slow evaporation solution growth technique using acetone as solvent at constant temperature (32 deg. C). The 2APNP easily crystallizes in orthorhombic system with noncentrosymmetric space group, Pna21, and the cell parameters are a = 13.152(2) A, b = 10.921(3) A, c = 12.241(3) A and V = 1758.3(7) A3. The structural perfection of the grown crystals has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. FT-IR study was performed for analyzing and assigning the vibrations and to identify the functional groups. The optical transparency window in the visible and near IR (480-1200 nm) regions was found to be good for nonlinear applications. The transmittance of 2APNP has been used to calculate the refractive index (n) as functions of wavelength. Thermogravimetric analysis and differential thermal analysis showed that the compound decomposes beyond 135 deg. C. The relative second harmonic efficiency of the compound is found to be 17 times greater than that of KDP. The dielectric behavior of the specimen was also studied.