Synthesis, crystal growth, structural and physicochemical properties of an organic single crystal (C11H16N2O4) for fast scintillation and NLO applications

Abstract

2-Amino-4-methyl pyridinium glutaric acid (2A4MGA) was synthesized and single crystals were grown from solution for the first time. From the single crystal X-ray diffraction (SCXRD) measurements, it was confirmed that the title compound crystallizes as a triclinic system and has a centrosymmetric nature with the space group P. The calculated unit cell parameters are as follows: a = 7.1853(7) Å, b = 9.5314(9) Å, c = 11.0896(11) Å, α = γ = 90°, β = 105.665(3)° and volume = 731.27(12) ų. The crystal structure was connected by the protonated 2-amino-4-methylpyridinium cations and the H-atoms in the carboxylic groups of the glutaric acid anions. The presence of various functional groups was studied, wherein the in-plane/out-of-plane stretching and symmetric/asymmetric vibrations were investigated through Fourier transform infrared (FT-IR) spectral analysis. From the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements, the thermal properties of the sample were investigated. The lower absorption edge was observed at 340 nm through UV-vis (ultraviolet-visible) spectral analysis, and the optical band gap was calculated to be 3.6 eV. The third-order optical susceptibility (χ⁽³⁾) of the sample was studied through the Z-scan spectra. Photoluminescence (PL) spectra for the grown crystal were recorded at room temperature and the peak emission was observed at 364 nm upon an excitation of 340 nm. The X-ray-induced emission spectrum shows a maximum peak at 364 nm. It has a fast scintillation decay time of 12 ns under γ-ray excitation from a ¹³⁷Cs radiation source, which is comparable with that of currently available organic scintillators. The results suggest that this crystal can be used as an organic scintillator and in NLO applications.