Thermochemical Study of the Solid Complexes Ln[(CH₃)₂NCS₂)]₃(C₁₂H₈N₂) (Ln = Eu, Gd, Tb, Dy)

Four solid complexes Ln(Me2dtc)3(phen) (Ln = Eu, Gd, Tb, Dy) have been prepared from the reactions of hydrous lanthanide chloride, sodium dimethyldithiocarbamate (NaMe2dtc), and 1,10-phenanthroline (phen·H2O) in anhydrous ethanol. The title complexes were characterized by elemental analysis, IR spectroscopy, TG−DTG−DSC, and X-ray diffraction analysis. Their enthalpy changes of liquid-phase reactions of formation, ΔrHmθ(l), were determined at 298.15 K by a microcalorimeter, and the enthalpy changes of the solid-phase reactions of formation, ΔrHmθ(s), were calculated on the basis of a thermochemical cycle. The thermodynamics of reactions of formation of the complexes were studied via the reactions in solution. Combining the thermochemical data of the reactions and kinetic equations with the data of thermokinetic experiments, fundamental thermodynamic and kinetic parameters were achieved. The molar heat capacities of the title complexes were determined using an improved RD496-III type microcalorimeter at 298.15 K

Synthesis, Structure, and Thermophysical Properties of an Energetic Complex Co(3-(2-pyridyl)-5-(3′-pyridyl)-1<i>H</i>-1,2,4-triazole)₃·H₂O

A new energetic complex, Co(2,3′-bpt)3·H2O (1) (2,3′-Hbpt = 3-(2-pyridyl)-5-(3′-pyridyl)-1H-1,2,4-triazole), was synthesized and characterized by single crystal X-ray diffraction method. Crystallographic data are as follows: triclinic, P1̅ space group, a = 10.323(2) Å, b = 11.261(2) Å, c = 16.139(3) Å, α = 89.022(3)°, β = 71.794(2)°, γ = 66.990(2)°, Z = 2. In addition, the thermal analysis of Co(2,3′-bpt)3·H2O has been performed by thermogravimetric-differential thermogravimetric (TG-DTG) techniques. The thermal decomposition of ammonium perchlorate (AP) with complex 1 was explored by differential scanning calorimetry (DSC) over the temperature range from (323 to 773) K. AP is completely decomposed in a shorter time in the presence of complex 1, and the decomposition heat of the mixture is 2.034 kJ·g–1, significantly higher than pure AP. By Kissinger's method, the ratio of Ea/ln(A) is 12.66 for the mixture, which indicates that complex 1 shows good catalytic activity toward AP decomposition

Structure, Physicochemical Properties, and Density Functional Theory Calculation of High-Energy-Density Materials Constructed with Intermolecular Interaction: Nitro Group Charge Determines Sensitivity

Four nitro-containing energetic compounds, cocrystal of AT·DNBA (<b>1</b>), salt of MA·DNSA (<b>2</b>), salt of AG·DNBA·H₂O (<b>3</b>), and salt of DAT·DNSA H₂O (<b>4</b>), are synthesized and structurally characterized based on supramolecular interactions (AT, 4-amino-1,2,4-triazole; DNBA, 3,5-dinitrobenzoic acid; MA, melamine; DNSA, 3,5-dinitrosalicylic acid; AG, amino guanidine; DAT, 3,5-diamino-1,2,4-triazole). The physicochemical properties of the compounds are theoretically and experimentally investigated in detail. The optimized structures, molecular total energies, frontier orbit energies, and charge densities of <b>1</b>–<b>4</b> are calculated by theoretical methods. The experimental results indicate that all compounds exhibit good thermostability and low sensitivity. It is worth noting that the values of impact sensitivity are measured to be 30, >40, 38, and >40 J for <b>1</b>, <b>2</b>, <b>3</b>, and <b>4</b>, respectively, which correspond well to the order of nitro group charge (<i>Q</i>_Nitro) calculated by density functional theory. The detonation performances of <b>1</b>–<b>4</b> are discussed; in particular, <b>1</b> and <b>2</b> exhibit heats of detonation (2.191 kcal g^–1 for <b>1</b> and 2.214 kcal g^–1 for <b>2</b>) superior to those of classical nitro-rich compounds. In addition, the nonisothermal thermokinetic parameters are obtained by Kissinger and Ozawa methods, and the standard molar enthalpies of formation are calculated from the determination of constant volume combustion energies

Copper-Based Energetic Coordination Polymers Regulated by CN^– and NO₃^– for the Combustion Decomposition of Ammonium Perchlorate

Energetic coordination polymers (ECPs) have good application prospects as combustion promoters of solid propellants. In this work, based on a rigid proton-free nitrogen-rich ligand 1,3,5-tri­(1H-1,2,4-triazol-1-yl)­benzene (TTB) and an environmentally friendly copper ion, two ECPs, {[Cu6(TTB)2(CN)6]·CH3CN}n (1) and {[Cu­(TTB)­(NO3)2]·CH3CN}n (2), were prepared by the solvothermal method using an anion regulation strategy. X-ray crystallographic analyses, thermal stability, kinetic parameters of exothermic decomposition process, thermal safety performances, mechanical sensitivity, and theoretical detonation characteristics of two ECPs were, respectively, explored. Meanwhile, their promoting effects on the combustion decomposition of ammonium perchlorate were investigated by differential scanning calorimetry tests, thermal decomposition kinetics, and surface morphology analyses. Experimental results indicated that ECP 2 has good application potential in the solid propellant field

Copper-Based Energetic Coordination Polymers Regulated by CN^– and NO₃^– for the Combustion Decomposition of Ammonium Perchlorate

Energetic coordination polymers (ECPs) have good application prospects as combustion promoters of solid propellants. In this work, based on a rigid proton-free nitrogen-rich ligand 1,3,5-tri­(1H-1,2,4-triazol-1-yl)­benzene (TTB) and an environmentally friendly copper ion, two ECPs, {[Cu6(TTB)2(CN)6]·CH3CN}n (1) and {[Cu­(TTB)­(NO3)2]·CH3CN}n (2), were prepared by the solvothermal method using an anion regulation strategy. X-ray crystallographic analyses, thermal stability, kinetic parameters of exothermic decomposition process, thermal safety performances, mechanical sensitivity, and theoretical detonation characteristics of two ECPs were, respectively, explored. Meanwhile, their promoting effects on the combustion decomposition of ammonium perchlorate were investigated by differential scanning calorimetry tests, thermal decomposition kinetics, and surface morphology analyses. Experimental results indicated that ECP 2 has good application potential in the solid propellant field

Enhancing Energetic Performance of Multinuclear Ag(I)-Cluster MOF-Based High-Energy-Density Materials by Thermal Dehydration

It is an enormous challenge to construct high-energy-density materials meeting simultaneously requirements of high energy and excellent stability. In this work, the reaction of a Ag­(I) ion with a nitrogen-rich ligand, 1H-tetrazole-5-acetic acid (H2tza), leads to a novel Ag7-cluster metal–organic framework, [Ag7(tza)3(Htza)2(H2tza)­(H2O)] (1), with remarkable high-energy content, stability, and insensitivity. Dramatically, the heating-dehydrated process of 1 produces a new stable energetic material, [Ag7(tza)3(Htza)2(H2tza)] (1a), which features superior energy and undiminished safety performance compared to those of 1

Dynamic Metal–Iodide Bonds in a Tetracoordinated Cadmium-Based Metal–Organic Framework Boosting Efficient CO₂ Cycloaddition under Solvent- and Cocatalyst-Free Conditions

Due to the inherent thermodynamic stability and kinetic inertness of CO2, heterogeneous catalytic conversion of CO2 to cyclic carbonates often requires harsh operating conditions, high temperature and high pressure, and the addition of cocatalysts. Therefore, the development of efficient heterogeneous catalysts under cocatalyst-free and mild conditions for CO2 conversion has always been a challenge. Herein, an infrequent tetracoordinated Cd-MOF was synthesized and used to catalyze CO2 cycloaddition reactions efficiently without the addition of any cocatalyst, and its catalytic mechanism was systematically investigated through a series of experiments, including fluorescence analysis, X-ray photoelectron spectroscopy, microcalorimetry, and density functional theory (DFT) calculation. Cd-MOF features a 3D supermolecule structure with 1D 11.6 × 7.7 Å2 channels, and the abundant Lewis acid/base and I– sites located in the confined channel boost efficient CO2 conversion with a maximum yield of 98.2% and a turnover number value of 1080.11 at 60 °C and 0.5 MPa, far surpassing most pristine MOF-based catalytic systems. A combined experimental and DFT calculation demonstrates that the exposed Cd­(II) Lewis acid sites rapidly participate in coordination to activate the epoxides, and the resulting large steric hindrance facilitates leaving of the coordinated iodide ions in a reversibly dynamic fashion convenient for the rate-determining step ring-opening as a strong nucleophile. Such a pristine MOF catalyst with self-independent catalytic ring-opening overcomes the complicated operation limitation of the traditional cocatalyst-free MOF systems based on encapsulating/postmodifying cocatalysts, providing a whole new strategy for the development of simple, green, and efficient heterogeneous catalysts for CO2 cycloaddition

Copper-Based Energetic Coordination Polymers Regulated by CN^– and NO₃^– for the Combustion Decomposition of Ammonium Perchlorate

Energetic coordination polymers (ECPs) have good application prospects as combustion promoters of solid propellants. In this work, based on a rigid proton-free nitrogen-rich ligand 1,3,5-tri­(1H-1,2,4-triazol-1-yl)­benzene (TTB) and an environmentally friendly copper ion, two ECPs, {[Cu6(TTB)2(CN)6]·CH3CN}n (1) and {[Cu­(TTB)­(NO3)2]·CH3CN}n (2), were prepared by the solvothermal method using an anion regulation strategy. X-ray crystallographic analyses, thermal stability, kinetic parameters of exothermic decomposition process, thermal safety performances, mechanical sensitivity, and theoretical detonation characteristics of two ECPs were, respectively, explored. Meanwhile, their promoting effects on the combustion decomposition of ammonium perchlorate were investigated by differential scanning calorimetry tests, thermal decomposition kinetics, and surface morphology analyses. Experimental results indicated that ECP 2 has good application potential in the solid propellant field

Copper-Based Energetic Coordination Polymers Regulated by CN^– and NO₃^– for the Combustion Decomposition of Ammonium Perchlorate

Energetic coordination polymers (ECPs) have good application prospects as combustion promoters of solid propellants. In this work, based on a rigid proton-free nitrogen-rich ligand 1,3,5-tri­(1H-1,2,4-triazol-1-yl)­benzene (TTB) and an environmentally friendly copper ion, two ECPs, {[Cu6(TTB)2(CN)6]·CH3CN}n (1) and {[Cu­(TTB)­(NO3)2]·CH3CN}n (2), were prepared by the solvothermal method using an anion regulation strategy. X-ray crystallographic analyses, thermal stability, kinetic parameters of exothermic decomposition process, thermal safety performances, mechanical sensitivity, and theoretical detonation characteristics of two ECPs were, respectively, explored. Meanwhile, their promoting effects on the combustion decomposition of ammonium perchlorate were investigated by differential scanning calorimetry tests, thermal decomposition kinetics, and surface morphology analyses. Experimental results indicated that ECP 2 has good application potential in the solid propellant field

Copper-Based Energetic Coordination Polymers Regulated by CN^– and NO₃^– for the Combustion Decomposition of Ammonium Perchlorate

Energetic coordination polymers (ECPs) have good application prospects as combustion promoters of solid propellants. In this work, based on a rigid proton-free nitrogen-rich ligand 1,3,5-tri­(1H-1,2,4-triazol-1-yl)­benzene (TTB) and an environmentally friendly copper ion, two ECPs, {[Cu6(TTB)2(CN)6]·CH3CN}n (1) and {[Cu­(TTB)­(NO3)2]·CH3CN}n (2), were prepared by the solvothermal method using an anion regulation strategy. X-ray crystallographic analyses, thermal stability, kinetic parameters of exothermic decomposition process, thermal safety performances, mechanical sensitivity, and theoretical detonation characteristics of two ECPs were, respectively, explored. Meanwhile, their promoting effects on the combustion decomposition of ammonium perchlorate were investigated by differential scanning calorimetry tests, thermal decomposition kinetics, and surface morphology analyses. Experimental results indicated that ECP 2 has good application potential in the solid propellant field