Crystal structure, molecular structural analysis, optical absorption and thermal analysis of 2-amino-6-methyl pyridine-1-ium 2-carboxy-6-nitro benzoate – A third harmonic nonlinear optical organic single crystal

Abstract

Single crystals of the newly concocted 2-amino-6-methyl pyridine-1-ium 2-carboxy-6-nitro benzoate (MPNP) were grown by slow evaporation approach using an equimolar ethanol-water mixed solvent. The crystal structure of MPNP with the single-crystal X-ray diffraction technique revealed a centrosymmetric triclinic molecular arrangement. A robust hydrogen bond network with a cloud of supramolecular assemblies, S (4), S (8), S (10) and S (11), ring graph set motifs, R22 (8), R44 (18) and R (10) and π – π linkages establish molecular packing. Hirshfeld surface analysis substantiated non-bonded interactions in the structure. Experimental FT-IR and Raman vibration modes were analyzed in order to establish the presence of functional groups and the amine-imine tautomeric form. Molecular structure confirmation was corroborated with experimental NMR spectra. UV–Visible spectral profiling with Tauc, Urbach, and dispersion plots for refractive index variations were performed to understand the origin of optical band in the material. TCSPC lifetime studies envisaged the immense scintillating efficacy of MPNP. The experimental Z-scan data of MPNP in the closed and open aperture modes were deployed to estimate the magnitude of the nonlinear optical properties of MPNP, thereby establishing a good scope for optical applications. Thermogravimetry coupled with Differential Scanning Calorimetry (DSC) declares high thermal stability of the material till 177.6 °C.