Metal Salts of 4-Chloro-3,5-dinitropyrazole for Promising Eco-Friendly Primary Colors Pyrotechnics.

The construction and design of pyrotechnics with superior performance is not only a task of great significance but also a tremendous challenge. In this regard, we present the syntheses of novel green primary colors pyrotechnics (red, green, and blue light-generating pyrotechnics) by employing 4-chloro-3,5-dinitropyrazole (CDNP) as a multifunctional raw material. CDNP contains a flame enhancer, oxygen-rich functional group, and nitrogen heterocyclic combustibles, which contribute to the high performance of the pyrotechnics. The characteristic elements (strontium, barium, and copper) that impart color to the flame are combined with the CDNP to synthesize the primary colors pyrotechnics by an "all-in-one" strategy. The structures of three energetic metal salts (EMS-1, EMS-2, and EMS-3) are completely characterized, and their thermal stability, sensitivity, ignition performance, and color purity are systematically evaluated. All EMSs show excellent thermal stability and low mechanical sensitivities (>330 °C, >40 J, >360 N). Moreover, the EMSs demonstrate successful ignition and combustion under laser conditions and roasting test conditions, producing bright characteristic flames. Chromaticity analysis reveals that the three EMSs possess good color purities of 91, 80, and 70%, respectively. Consequently, the three integrated pyrotechnics exhibit exceptional combustion properties, highlighting their potential for use in various pyrotechnic applications.

Synthesis, Crystal Structure, and Characterization of Energetic Salts Based on 3,5-Diamino-4H-Pyrazol-4-One Oxime.

In order to broaden the study of energetic cations, a cation 3,5-diamino-4H-pyrazol-4-one oxime (DAPO) with good thermal stability was proposed, and its three salts were synthesized by a simple and efficient method. The structures of the three salts were verified by infrared spectroscopy, mass spectrometry, elemental analysis, and single crystal X-ray diffraction. The thermal stabilities of the three salts were verified by differential scanning calorimetry and thermos-gravimetric analysis. DAPO-based energetic salts are analysed using a variety of theoretical techniques, such as 2D fingerprint, Hirshfeld surface, and non-covalent interaction. Among them, the energy properties of perchlorate (DAPOP) and picrate (DAPOT) were determined by EXPLO5 program combined with the measured density and enthalpy of formation. These compounds have high density, acceptable detonation performance, good thermal stability, and satisfactory sensitivity. The intermolecular interactions of the four compounds were studied by Hirshfeld surface and non-covalent interactions, indicating that hydrogen bonds and π-π stacking interactions are the reasons for the extracellular properties of perchlorate (DAPOP) and picrate (DAPOT), indicating that DAPO is an optional nitrogen-rich cation for the design and synthesis of novel energetic materials with excellent properties.

Structure and performance regulation of energetic complexes through multifunctional molecular self-assembly.

The design of novel energetic compounds constitutes a pivotal research direction within the field of energetic materials. However, exploring the intricate relationship between their molecular structure and properties, in order to uncover their potential applications, remains a challenging endeavor. Therefore, employing multi-molecule assembly techniques to modulate the structure and performance of energetic materials holds immense significance. This approach enables the creation of a new generation of energetic materials, fueling research and development efforts in this field. In this study, a series of coordination compounds are synthesized by utilizing tetranitroethide (TNE) as an anion, which possesses a high nitrogen and oxygen content. The synthesis involves the synergistic modification between metal ions and small molecule ligands. Characterization of the obtained compounds is carried out using various techniques, including single crystal X-ray diffraction, IR spectroscopy, elemental analysis, and simultaneous TG-DSC analysis. Additionally, the energy of formation for these compounds is calculated using bomb calorimetry, based on the heat of combustion. The detonation performances of the compounds are determined through calculations using the EXPLO 5 software, and their sensitivities to external stimuli are evaluated.

A multi-fused heat-resistant energetic compound constructed by hydrogen bonds.

The design of heat-resistant energetic compounds generally employs symmetry, planarity, and multi-hydrogen bonds to obtain compounds with high density, good thermal stability, and low sensitivity. In this paper, a heat-resistant hydrazine-bridged compound, 6,6'-(hydrazine-1,2-diyl)bis(5-nitropyrimidine-2,4-diamine) (PHP), was designed and synthesized with the strategy of multi-fused conjugated structure constructed by hydrogen bonds. The compound featured high symmetry, high planarity, and strong conjugation with good thermal stability (364 °C). This strategy provides a basis for the design of heat-resistant energetic compounds.

Splicing oxygen-rich multidentate ligands and characteristic metals to construct flame colorants: abundant structures and attractive colors.

Tetranitroethane (TNE), an energetic compound with high-nitrogen (N%, 26.7%) and oxygen (O%, 60.9%) content, is deprotonated by alkali and alkaline earth metal bases to form the corresponding metal salts of TNE which are characterized by FT-IR spectroscopy, elemental analysis, and single crystal X-ray diffraction. All the prepared energetic metal salts show excellent thermal stabilities, and the decomposition temperatures of EP-3, EP-4, and EP-5 are higher than 250 °C, due to the numerous coordination bonds of the complexes. Furthermore, the energy of formation of the nitrogen-rich salts were calculated utilizing heat of combustion. The detonation performances were calculated with the EXPLO5 software, and the impact and friction sensitivities were determined. EP-7 shows excellent energy performance (P = 30.0 GPa, VD = 8436 m s-1). EP-3, EP-4, EP-5, and EP-8 are more sensitive to mechanical stimulation. These alkali and alkaline earth metal salts of TNE show good monochromaticity by atomic emission spectroscopy (visible light), and may be used as potential flame colorants in pyrotechnics.

Combining the advantages of 1,3,4-oxadiazole and tetrazole enables achieving high-energy insensitive materials.

Combining the advantages of energetic heterocycles to achieve high-energy insensitive explosives is a significant challenge. Herein, based on high-energy tetrazole rings and highly stable 1,3,4-oxadiazole rings, a series of novel nitrogen rich energetic compounds 5-9 were successfully constructed. The related compounds were fully characterized by EA, FT-IR, NMR, DSC, and MS, and compounds 6-9 were further confirmed by X-ray single crystal diffraction. Among them, the energetic ion salts 6-8 show high thermal stability (Tdec > 250 °C) and low mechanical sensitivity (IS > 40 J, FS > 360 N), as well as good energy properties (7552-8050 m s-1, 19.4-23.3 GPa). In particular, the azo compound 9 exhibits competent comprehensive performances (Tdec = 226.2 °C, D = 8502 m s-1, P = 28.9 GPa, IS = 32 J, FS = 320 N). These results suggest that the strategy of integrating tetrazole and 1,3,4-oxadiazole and employing an azo structure as a bridging unit are effective approaches to construct high-energy insensitive materials.

Energetic bimetallic complexes as catalysts affect the thermal decomposition of ammonium perchlorate.

Two bimetallic complexes of 4-hydroxy-3,5-dinitropyrazole, [K2Mn(DNPO)2(H2O)4]n·2H2O (BMEP-1) and [K2Zn(DNPO)2(H2O)6]n (BMEP-2), were synthesized and characterized by IR spectroscopy and elemental analysis. The crystal structures of BMEP-1 and BMEP-2 were determined by single-crystal X-ray diffraction. It is noteworthy that these complexes presented different metal-organic frameworks. The thermal behaviors of BMEP-1 and BMEP-2 were investigated by differential scanning calorimetry and thermogravimetric analysis measurements. These bimetallic complexes exhibited high thermal stability (348.0 °C and 331.0 °C) due to their large coordination bonds and three-dimensional interconnected structure. The catalytic performances of BMEP-1 and BMEP-2 on the thermal decomposition of ammonium perchlorate were investigated by TGA-DSC, TGA-FTIR, and non-isothermal kinetic analyses. The results showed that BMEP-1 and BMEP-2 exhibited excellent catalytic performance in the thermal decomposition of ammonium perchlorate. Notably, there was only a single exothermic peak at 302.6 °C and 318.6 °C, and the activation energy values of ammonium perchlorate decreased to 123.88 kJ mol-1 and 128.43 kJ mol-1, respectively. TGA-FTIR results showed that BMEP-1 and BMEP-2, as effective components of catalysis, will promote the production of H2O, N2O, NO2, and HCl in advance, during the thermal decomposition of ammonium perchlorate. BMEP-1 and BMEP-2 are expected to be two candidate additives for the catalytic decomposition of ammonium perchlorate in composite solid propellants.

Effects of Home-based Telesupervising Rehabilitation on Physical Function for Stroke Survivors with Hemiplegia: A Randomized Controlled Trial.

OBJECTIVE: The aims of this work were to evaluate the effects of home-based telesupervising rehabilitation on physical function for stroke survivors with hemiplegia and to determine if the rehabilitation therapy can relieve the burden on caregivers. DESIGN: This study is a randomized, controlled, assessor-blinded trial. Stroke survivors were randomly assigned to either home-based telesupervising rehabilitation group or conventional rehabilitation group to receive physical exercise and electromyography-triggered neuromuscular stimulation. Modified Barthel Index, Berg Balance Scale, modified Rankin Scale, Caregiver Strain Index, root mean square of extensor carpi radialis longus and tibialis anterior muscle were measured at 3 time points: baseline, postintervention (12 weeks), and 12-week follow-up (24 weeks). RESULTS: Both the home-based telerehabilitation and conventional rehabilitation groups demonstrated significant effects within groups over the 3 time points in increasing Modified Barthel Index, Berg Balance Scale, and root mean square value of extensor carpi radialis longus and tibialis anterior, as well as decreasing Caregiver Strain Index (P < 0.001), but none of the between-group differences was significant. For modified Rankin Scale, the percentage of participants of grades 0 and 1 in 2 groups increased over time without significant difference between the groups. CONCLUSIONS: Home-based telesupervising rehabilitation is most likely as effective as the conventional outpatient rehabilitation for improving functional recovery in stroke survivors and could ease the burden of caregivers as conventional rehabilitation.