Search

Seven energetic salts of 3,6-dinitramino-1,2,4,5-tetrazine (DNAT), named as (NH4)2(DNAT) (1), (NH2NH3)2(DNAT) (2), (NH3OH)2(DNAT) (3), G2(DNAT) (4) (G = guanidine), (AG)2(DNAT) (5) (AG = aminoguani...

3-Nitramino-6-hydroxy-1,2,4,5-tetrazine (NHTZ) and its alkaline earth metal salts (Mg2+(1), Ca2+(2), Sr2+(3), Ba2+(4)) were prepared via 3,6-dinitramino-1,2,4,5-tetrazine for the first time. The electrostatic potentials and HOMO-LUMO orbitals of them were computed to better understand the electronic structure of NHTZ. Structures of the four alkaline earth metal salts were confirmed by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analysis revealed that all compounds have differently dimensional structures, increasing with the radius of metal atoms. Compounds 3 and 4 can be classified as coordination polymers due to their structural features. As the only 3D polymeric structure in this series, compound 4 possesses the highest density and best thermal stability in these compounds. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurement shows the excellent thermal stability of these salts, with the thermal decomposition temperatures of 291.1°C (1), 294.1°C (2), 294.9°C (3) and 324.7°C (4). Heat of formation and sensitivity of the four salts were investigated, which suggest 4 as a potential heat-resistant energetic compound instructions for authors.

The alkali metal salts of 3,6-dinitramino-1,2,4,5-tetrazine (DNAT, 1), Li2(H2O)4(DNAT) (2), Na2(H2O)3(DNAT) (3), K2(H2O)(DNAT) (4), Rb2(DNAT) (5) and Cs2(DNAT) (6) were synthesized and characterized by elemental analysis, IR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and single-crystal X-ray diffraction. All of these alkali metal salts possess higher thermal stability (from 240.9 °C to 260.0 °C) than that of DNAT substrate (108.3 °C) due to their numerous coordination bonds and the three-dimensional network structures of the complexes. The number of coordination water molecules, the atomic radius of metal and the different packing forms of the crystal structure contribute to the different thermal stabilities of the alkali metal salts. The experimental (constant-volume) energy of combustion values range from 1331 to 1531 kJ mol−1. The compounds 1, 4, 5, and 6 are sensitive to impact and friction.

Two energetic complexes, Fe2II(DTMone)2(H2O)6 (1) and Fe2IIIO(DTMone)2(H2O)12 (2) [H2DTMone = di(1H-tetrazol-5-yl) methanone] were synthesized and characterized by FT-IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The coordination complex (1) and (2) belong to the P21/n and P1 space group, respectively. Both Iron cations are six-coordinated in octahedral fashion, by N atoms and O atoms. However, the O atoms of (2) have one free atom which is different from (1). The structure of complex (2) is analogous to two dimension structure due to the oxygen ligands participating in the coordination. Their thermal stabilities were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Additionally, the DSC measurements display that the dehydrated polymers possess excellent thermal stability, and the thermal decomposition peak temperature is as high as 285 °C. The sensitivities to external stimuli were determined with BAM standard methods as for impact >40 J (TNT,15J) and for friction >360 N.

Background Kilohertz-frequency electric field stimulation (kEFS) applied to the spinal cord can reduce chronic pain without causing the buzzing sensation (paresthesia) associated with activation of dorsal column fibers. This suggests that high-rate spinal cord stimulation (SCS) has a mode of action distinct from conventional, parasthesia-based SCS. A recent study reported that kEFS hyperpolarizes spinal neurons, yet this potentially transformative mode of action contradicts previous evidence that kEFS induces depolarization and was based on patch clamp recordings whose accuracy in the presence of kEFS has not been verified. Objectives We sought to elucidate the basis for kEFS-induced hyperpolarization and to validate the effects of kEFS observed in patch clamp recordings by comparing with independent optical methods. Methods Using patch clamp electrophysiology and voltage-sensitive dye (VSD) imaging, we measured the response to kEFS applied in vitro to hippocampal and spinal neurons. Results The kEFS-induced hyperpolarization observed with current clamp recordings was corroborated by VSD imaging and rheobase measurements in patched neurons. However, no hyperpolarization was observed when imaging unpatched neurons or when recording with a voltage-follower amplifier rather than with a patch clamp amplifier (PCA). We found that EFS induced an artifactual current in PCAs that was injected back into current clamped neurons. The artifactual current induced by single, charge-balanced EFS pulses caused modest hyperpolarization, but these unitary hyperpolarizations accumulated when EFS pulses were repeated at kilohertz frequencies. Conclusion Our results rule out hyperpolarization as the mechanism underlying kEFS-mediated analgesia and highlight the risk of recording artifacts caused by extracellular electrical stimulation.

Two nitrogen-rich energetic salts (NH4)2(bto) (1) and (NH3OH)2(bto)·H2O (2) [H2bto = Bis (1H-tetrazol-5-yl) methanone oxime] were synthesized by an improved method in which water was used as solvent. These compounds were characterized by FT-IR spectroscopy, elemental analysis and single crystal X-ray diffraction. Their crystal structures were confirmed to belong to monoclinic system with space group P21 for 1 and Pc for 2, respectively. The detailed thermal behaviours were investigated by using differential scanning calorimetry (DSC) and thermogravimetric method (TG) (decomposition temperature >250 °C). The enthalpies of formation were calculated through the experimental values of combustion enthalpy. In addition, the sensitivities toward impact and friction were tested with standard methods, and those results indicated that two compounds are all insensitive (impact >40 J and friction >360 N). In short, both of the compounds show potential usages as energetic materials. The improved process opens a door for exploring nitrogen-rich salts based on Bis (1H-tetrazol-5-yl) methanone oxime.

Nitrogen-rich energetic salts and cocrystal have attracted considerable attention in recent years. To assess the formation of cocrystal or salt, acid dissociation constant (pKa) values of the isomeric co-formers were calculated in this work and significant differences were observed. Two salts and one cocrystal based on H2BT (1H, 1′H-5,5′-bitetrazole), DATr (4,5-diamino-4H-1,2,4-triazole), 1MAT (1-methyl-5-aminotetrazole) and 2MAT (2-methyl-5-aminotetrazole) were synthesized, which corresponding to the different pKa values of three isomeric coformers. Single crystal structure analysis reveals that all compounds are formed by layered stacking structure with π-π stacking and rich hydrogen bonds, resulting in the insensitivity towards impact and friction (impact sensitivity > 40 J, friction sensitivity > 360 N). To the best of our knowledge, it is the first time to report the cocrystal of H2BT. The study results provide a utility method to seek for suitable coformers and design energetic cocrystal through the calculation of pKa.

Four alkaline earth metal salts (Mg2+(1), Ca2+(2), Sr2+(3), Ba2+(4)) of 3,6-dinitramino-1,2,4,5-tetrazine were synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analysis revealed that all compounds have differently reticular structures, where each metal is bound in a specific and characteristic fashion. Thermal behaviors investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) show that all of these salts possess better thermal stability compared to neutral 3,6-dinitramino-1,2,4,5-tetrazine, with the thermal decomposition temperatures of 162 °C (1), 262.1 °C (2), 268 °C (3) and 267 °C (4), respectively, due to their plenty of coordinate bonds and intermolecular H-bonds. Besides, the kinetic parameters have been determined by non-isothermal kinetics at various heating rates. All these salts are insensitive to the stimulation of impact and friction (impact sensitivity > 40 J, friction sensitivity > 360 N), which can be considered as potential eco-friendly insensitive energetic compounds.

Lysophosphatidic acid (LPA), which is one of the intermediate products of membrane phospholipid metabolism, is a bioactive phospholipid that possesses diverse activities. In the present study, the effects of LPA on neointimal formation following vascular injury were investigated. A carotid artery balloon injury model was employed in the present study, and following vascular injury, rats received an intraperitoneal injection of 1 mg/kg LPA. Subsequently, histopathological alterations were assessed by hematoxylin and eosin staining, the expression levels of proliferating cell nuclear antigen (PCNA) were detected by immunohistochemistry, apoptosis was assessed via a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and the expression levels of apoptosis-associated and autophagy-associated proteins were detected by western blotting. In addition, inflammatory and oxidative stress-associated factors were assessed by reverse transcription-quantitative polymerase chain reaction or corresponding kits. The results of the present study demonstrated that LPA enhanced vascular injury-induced neointimal hyperplasia. LPA further elevated the expression levels of PCNA in the injured carotid artery tissues. LPA exhibited no effect on apoptosis in carotid artery tissues, whereas it modulated autophagy in the injured carotid artery tissues. Furthermore, LPA enhanced vascular injury-induced inflammation and oxidative stress. The present study demonstrated that LPA may enhance neointimal hyperplasia following vascular injury by modulating proliferation, autophagy, inflammation and oxidative stress, but not apoptosis. Furthermore LPA may contribute to the pathology of atherosclerosis and may be considered a promising therapeutic target for the treatment of atherosclerosis.