Xiao-Jing Qiao

Crystal Structure and Thermal Decomposition of 5-Aminotetrazole Trinitrophloroglucinolate

Abstract 5-Aminotetrazole trinitrophloroglucinolate ((ATZ)TNPG) was prepared and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray diffraction analysis and it belonged to orthorhombic system and Pbca space group with a=0.6624(2) nm, b=1.7933(4) nm, c=2.3117(5) nm, V=2.7458(9) nm3, Z=4, and Dc=1.849 g·cm−3. The molecular formula was confirmed to be (ATZ)TNPG·2H2O. 5-Aminotetrazole cation (ATZ+) and trinitrophloroglucinol anion (TNPG−) were linked into 2-D layers along b-axis and c-axis by hydrogen bonds. Then the layers were linked along a-axis by hydrogen bonds between the water molecules belonging to different layers. The thermal decomposition mechanism of the compound was studied by differential scanning calorimetry (DSC), thermogravimetry-thermogravimetric analysis (TG-DTG), and Fourier transform-infrared (FT-IR) spectroscopy techniques. Under nitrogen atmosphere with a heating rate of 10 °C·min−1, the compound experienced one endothermic process with peak temperature of 76 °C and one exothermal process with peak temperature of 203 °C. The former was confirmed to be a dehydrate process. The latter was the decomposition of TNPG− and ATZ+ in the compound. The exothermic enthalpy change of this process was −212.10 kJ·mol−1. The kinetic parameter calculation from Kissingers method were, E=132.1 kJ·mol−1, ln(A/s−1)=12.54 with r=0.9990, and the calculation results from Ozawa-Doyles method were, E=133.1 kJ·mol−1 with r=0.9992.

Structurally different cadmium(II) and lead(II) supramolecular polymers with the same benzene-1,2,3,4-tetracarboxylate dianion as bridging ligands from hydrothermal reactions

Two crystalline metal-organic frameworks, [Cd2(o-BTC)(H2O)2] n (1) and [Pb2(o-BTC)] n (2) (o-BTC = benzene-1,2,3,4-tetracarboxylic), were synthesized under hydrothermal conditions and characterized by analytical, spectroscopic and single crystal X-ray diffraction studies, which reveal three-dimensional reticular structures via M2+ and carboxylate ligands. All carboxyl groups of o-BTC are deprotonated, in agreement with the IR data. The Cd2+ centers of 1 have one coordination environment, while Pb2+ centers of 2 have two coordination environments. Both 1 and 2 form 3D interpenetrated grid structures along the b and c axes, respectively.

Preparation, Crystal Structure, and Thermal Analysis of Carbohydrazide Trinitrophloroglucinolate

A new compound (CHZ)(HTNPG)·0.5H2O was synthesized by mixing carbohydrazide(CHZ) and trinilrophloroglucinol(TNPG) and characterized by elemental analysis and Fourier transform infrared (FTIR) spectrum. Its crystal structure was determined by single crystal X-ray diffraction analysis. The crystal belongs to triclinic system, P space group, with a=0.45578(9) nm, b=1.0142(2) nm, c=1.3041(3) nm, α=86.53(3)°, β=99.56(3)°, γ=81.94(3)°, V= 0.5958(2) nm3, Z=2, Dc=2.008 g/cm3, R1,=0.0476, and wR2=0.1139. The compound is a di-substituted salt of TNPG, which consists of a cation (CHZ)2+ and an anion (HTNPG)2+. The thermal analysis of the compound was studied by means of differential scanning calorimetry(DSC) and thermogravimetry-derivative thermogravimetry(TG-DTG). Under nitrogen atmosphere at a heating rate of 10 °C/min, the thermal decomposition of the compound contained one endothermic process of dehydrating stage and two intense exothermic decomposition processes in a temperature range of 140—232 °C on the DSC trace. The decomposition products of the title compound are nearly gaseous products. The existing complicated hydrogen bond networks and electrostatic attraction between (CHZ)2+ and (HTNPG)2- enhance the thermal stability of the title compound.