The crystal magnification, characterization, X-ray single crystal structure, thermal behavior, and computational studies of the 2,4,6-trimethylpyridinium picrate

Abstract

A crystal of organic salt, 2,4,6-trimethylpyridinium picrate (TMPPc), was synthesized and magnified by slow evaporation in a polar aprotic solvent and characterized by ¹H NMR, ¹³C NMR, and FT-IR spectroscopic methods. X-ray diffraction analysis of the crystal structure of the compound TMPPc showed the presence of a monoclinic space group with a = 4.0174(4) Å, b = 27.863(3) Å, c = 13.9247(17) Å, β = 95.741(4)°, V = 1550.9(3) Å³, Z = 4, T = 296 K, μ(MoKα) = 0.123 mm^-1, Dcalc = 1.500 g/cm³, 62749 reflections measured (5.88° ≤ 2Θ ≤ 57.058°), 3911 unique (R_int = 0.0536, R_sigma = 0.0226) which were used in all calculations. The final R₁ was 0.0569 (I > 2σ(I)) and wR₂ was 0.1710 (all data). Detailed investigation of molecular packing of the TMPPc molecule indicated the presence of intermolecular hydrogen bond between N4-H44···O1 and C13-H13B···O4 that generates C₂²(14) chain running parallel to the [001] direction. The infrared and Raman spectra of the prepared TMPPc compound were recorded and discussed. The thermal stability of the obtained TMPPc crystal was analysed by TGA/DTG technique and revealed that the crystal was stable up to 162 °C. Density functional theory calculations such as the value of the HOMO and LUMO energy gap, the parameters of the molecular electrostatic potential, the global reactivity and thermodynamic properties of the compound TMPPc were also performed using the DFT/B3LYP method with the level of the 6-311G (d, p) basis set.