Crystal growth and characterization of 2-amino-6-methylpyridinium p-chlorobenzoate dihydrate single crystal: a novel third-order nonlinear optical material for optoelectronic applications

The organic single crystal of 2-amino-6-methylpyridinium p-chlorobenzoate dihydrate (2A6MP) single crystal was successfully grown by the slow evaporation method. The structural parameters of grown 2A6MP single crystal were confirmed by the single crystal X-ray diffraction technique. It revealed that 2A6MP crystal belongs to the centrosymmetric crystal structure with the space group of P121/c1. The crystallinity nature was confirmed by the powder XRD analysis. FT-IR spectroscopy was used to find out the presence of functional groups in the 2A6MP crystal. UV–Vis spectrometer analysis showed that 2A6MP crystal has a lower cut-off wavelength at 349 nm in the UV region and the 66% transmittance in the visible region ensured that the grown crystal is well suitable for nonlinear optical applications. From the photoluminescence spectrum, the emission peaks are at 378 nm in the violet region and 428, 478 nm in the blue region revealed the 2A6MP crystal is useful for violet and blue emitting diodes. The 2A6MP crystal was thermally stable upto the temperature rate of 106.8 °C was confirmed by the thermogravimetric/differential scanning calorimetric analysis. The mechanical properties of 2A6MP crystal were investigated using a Vickers microhardness tester, and the results revealed that the title compound has relates to the soft material category which is useful for optoelectronic applications. From the Z-scan technique, the third-order nonlinear properties such as nonlinear refractive index, nonlinear absorption co-efficient, and third-order susceptibility of the grown 2A6MP crystal was found to be − 4.25 × 10–09 m2/W and 3.16 × 10–04 m/W and 4.95 × 10–06 esu. All of these investigations were carried out for the first time, with the goal of determining the useful and safe range of thermal, optical, and mechanical properties in order to improve their usefulness for device production. Density functional theory (DFT) was carried out using Gaussian 09 program with the basis set of B3LYP/6-311 + + G (d, P), to find out the molecular geometry, frontier molecular orbital energies, molecular electrostatic potential, Mulliken, and natural bond orbital analysis of the grown 2A6MP crystal theoretically and it ensures the intermolecular charge transfer mechanism of 2A6MP crystal that induced the nonlinearity.