Spectral, thermal, structural and quantum chemical calculations of 3,5-dimethyl-1H-pyrazol-2-ium-3-hydroxy-2,4,6-trinitrophenolate - A new organic proton transfer crystal

Single crystals of a new proton transfer optical material, 3,5-dimethyl-1H-pyrazol-2-ium-3-hydroxy-2,4,6-trinitrophenolate (DPHTP), were obtained using slow evaporation of methanolic solution containing 1:1 M quantities of 3,5 dimethyl-1H-pyrazole and 3-hydroxy 2,4,6-trinitro phenol (styphnic acid). Asymmetric unit of DPHTP contains a univalent 3,5- dimethylpyrazolium cation with a univalent 3-hydroxy-2,4,6-trinitrophenolate anion. The various types of carbon atoms and protons in the compound were established using 1H and 13C NMR spectral studies. Thermal stability and decomposition pattern of DPHTP were studied by TG/DTA. The optical nonlinearities of DPHTP have been investigated by Z-scan technique with He-Ne laser radiation of wavelength 632.8 nm. The equilibrium optimized geometry, the first order hyperpolarizability calculations, molecular electrostatic interactions, frontier molecular orbital analysis, Mulliken population analysis have been calculated by density functional theoretical (DFT) method with (B3LYP)/6-311++G(d,p) level of basis set. First order hyperpolarizability (β) of DPHTP is 22 times greater than that of urea.