Qingchun Zhang

Synthesis, characterization and properties of nitrogen-rich compounds based on cyanuric acid: a promising design in the development of new energetic materials

Nitrogen-rich compounds such as ammonium (1), hydrazinium (2), aminoguanidinium (3), diaminoguanidinium (4), triaminoguanidinium (5), aminonitroguanidinium (6), aminocarbonylguanidinium (7), and metforminium (8), based on a nitrogen-rich anion [CA− (N% = 32.55%, CA = cyanuric acid) and co-crystal 5-amino-1H-tetrazole based on CA (9) were synthesized by means of metathesis reactions. The crystal structures of compounds 2, 4, and 9·H2O were determined by single-crystal X-ray diffraction and fully characterized by UV-vis, FT-IR, 1H NMR, MS and elemental analysis. The thermal stabilities were investigated by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The DTA results show that all compounds exhibit high thermal stabilities. Additionally, the heats of formation were calculated by using the B3LYP functional with the 6-311++G** basis set and a Born–Haber energy cycle. Theoretical calculations provided detonation pressures and velocities of the energetic salts within the range of 16.88–30.71 GPa and 6276.5–8392.1 m s−1, respectively. Impact sensitivities of the compounds were determined by the Fall hammer test. All compounds show insensitive impact sensitivities of >60 J, which are better than those of TATB (50 J).

Nitrogen-Rich Energetic Metal-Organic Framework: Synthesis, Structure, Properties, and Thermal Behaviors of Pb(II) Complex Based on N,N-Bis(1H-tetrazole-5-yl)-Amine

The focus of energetic materials is on searching for a high-energy, high-density, insensitive material. Previous investigations have shown that 3D energetic metal–organic frameworks (E-MOFs) have great potential and advantages in this field. A nitrogen-rich E-MOF, Pb(bta)·2H2O [N% = 31.98%, H2bta = N,N-Bis(1H-tetrazole-5-yl)-amine], was prepared through a one-step hydrothermal reaction in this study. Its crystal structure was determined through single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, and elemental analysis. The complex has high heat denotation (16.142 kJ·cm−3), high density (3.250 g·cm−3), and good thermostability (Tdec = 614.9 K, 5 K·min−1). The detonation pressure and velocity obtained through theoretical calculations were 43.47 GPa and 8.963 km·s−1, respectively. The sensitivity test showed that the complex is an impact-insensitive material (IS > 40 J). The thermal decomposition process and kinetic parameters of the complex were also investigated through thermogravimetry and differential scanning calorimetry. Non-isothermal kinetic parameters were calculated through the methods of Kissinger and Ozawa-Doyle. Results highlighted the nitrogen-rich MOF as a potential energetic material.

Nitrogen-rich energetic salts of 1H,1′H-5,5′-bistetrazole-1,1′-diolate: synthesis, characterization, and thermal behaviors

A series of nitrogen-rich heterocyclic 1H,1′H-5,5′-bistetrazole-1,1′-diolate salts, namely, 1,2,4-triazolium (2), 3-amino-1,2,4-triazolium (3), 4-amino-1,2,4-triazolium (4), 3,5-diamino-1,2,4-triazolium (5), 2-methylimidazolium (6), imidazolium (7), pyrazolium (8), 3-amino-5-hydroxypyrazolium (9), dicyandiamidine (10), and 2,4-diamino-6-methyl-1,3,5-triazin (11), was synthesized with cations. These energetic salts were fully characterized through FT-IR, 1H NMR, 13C NMR, and elemental analysis. The structures of 2, 3·7H2O, 6·2H2O, 8, and 10·4H2O were further confirmed through single crystal X-ray diffraction. Their thermal stabilities were investigated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated that all of the salts possess excellent thermal stabilities with decomposition temperatures ranging from 225.7 °C to 314.0 °C. On the basis of the Kamlet–Jacobs formula, we carefully calculated their detonation velocities and detonation pressures. All of the salts, except 11, exhibit promising detonation performances with a detonation pressure of 20.23–28.69 GPa and a detonation velocity of 7050–8218 m s−1. These values are much higher than those of TNT. The impact sensitivities of the compounds were determined via a Fall hammer test. All of the compounds show excellent impact sensitivities of >50 J, and this finding is higher than that of TATB (50 J). Therefore, these ionic salts with excellent energetic properties could be applied as new energetic materials.

Large-area snow-like MoSe2 monolayers: synthesis, growth mechanism, and efficient electrocatalyst application

This study explores the large-area synthesis of controllable morphology, uniform, and high-quality monolayer. MoSe2 is essential for its potential application in optoelectronics, photocatalysis, and renewable energy sources. In this study, we successfully synthesized snow-like MoSe2 monolayers using a simple chemical vapor deposition method. Results reveal that snow-like MoSe2 is a single crystal with a hexagonal structure, a thickness of ∼0.9 nm, and a lateral dimension of up to 20 μm. The peak position of the photoluminescence spectra is ∼1.52 eV corresponding to MoSe2 monolayer. The growth mechanism of the snow-like MoSe2 monolayer was investigated and comprised a four-step process during growth. Finally, we demonstrate that the snow-like MoSe2 monolayers are ideal electrocatalysts for hydrogen evolution reactions (HERs), reflected by a low Tafel slope of ∼68 mV/decade. Compared with the triangular-shaped MoSe2 monolayer, the hexangular snow-like shape with plentiful edges is superior for perfect electrocatalysts for HERs or transmission devices of optoelectronic signals.

New tris(dopamine) derivative as an iron chelator. Synthesis, solution thermodynamic stability, and antioxidant research

A new tris(dopamine) derivative, containing three dopamine chelate moieties which were attached to a trimesic acid molecular scaffold, has been prepared and fully characterized by NMR, FTIR and HRMS. The solution thermodynamic stability of the chelator with Fe(III), Mg(II), Zn(II) and Fe(II) ions was investigated. Results demonstrated that the chelator exhibited effective binding ability and improved selectivity to Fe(III) ion. The chelator possessed affinity similar to that of diethylenetriaminepentaacetic acid chelator for Fe(III) ion. The high affinity could be attributed to the favorable geometric arrangement between the chelator and Fe(III) ion coordination preference. The chelator also exhibited high antioxidant activity and nontoxicity to neuron-like rat pheochromocytoma cells. Hence, the chelator could be used as chelating agent for iron overload situations without depleting essential metal ions, such as Mg(II) and Zn(II) ions.

The mono(catecholamine) derivatives as iron chelators: synthesis, solution thermodynamic stability and antioxidant properties research

There is a growing interest in the development of new iron chelators as novel promising therapeutic strategies for neurodegenerative disorders. In this article, a series of mono(catecholamine) derivatives, 2,3-bis(hydroxy)-N-(hydroxyacyl)benzamide, containing a pendant hydroxy, have been synthesized and fully characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy and mass spectrum. The thermodynamic stability of the chelators with FeIII, MgII and ZnII ions was then investigated. The chelators enable formation of (3 : 1) FeIII complexes with high thermodynamic stability and exhibited improved selectivity to FeIII ion. Meanwhile, the results of 1,1-diphenyl-2-picryl-hydrazyl assays of mono(catecholamine) derivatives indicated that they all possess excellent antioxidant properties. These results support the hypothesis that the mono(catecholamine) derivatives be used as high-affinity chelator for iron overload situations without depleting essential metal ions, such as MgII and ZnII ions.

Novel enterobactin analogues as potential therapeutic chelating agents: Synthesis, thermodynamic and antioxidant studies

A series of novel hexadentate enterobactin analogues, which contain three catechol chelating moieties attached to different molecular scaffolds with flexible alkyl chain lengths, were prepared. The solution thermodynamic stabilities of the complexes with uranyl, ferric(III), and zinc(II) ions were then investigated. The hexadentate ligands demonstrate effective binding ability to uranyl ion, and the average uranyl affinities are two orders of magnitude higher than 2,3-dihydroxy-N1,N4-bis[(1,2-hydroxypyridinone-6-carboxamide)ethyl]terephthalamide [TMA(2Li-1,2-HOPO)2] ligand with similar denticity. The high affinity of hexadentate ligands could be due to the presence of the flexible scaffold, which favors the geometric agreement between the ligand and the uranyl coordination preference. The hexadentate ligands also exhibit higher antiradical efficiency than butylated hydroxyanisole (BHA). These results provide a basis for further studies on the potential applications of hexadentate ligands as therapeutic chelating agents.

Water-soluble [60] fullerene derivatives as potential chelating agents of radionuclides via chlorofullerene (C60Cl6) as a precursor

ABSTRACT The reactions of catecholamide ligands with hexachlorofullerene via O-nucleophiles yielded new water-soluble [60] fullerene derivatives as chelators for radionuclides decorporation. The derivatives were characterized through 1H NMR spectroscopy, FT-IR spectroscopy, and X-ray photoelectron spectroscopy. The affinities of the chelators were investigated through the fluorescence quenching of simulated nuclide Ce(III) via a linear Stern–Volmer plot method. Conditional stability constant (K) could also be estimated with this method. The antioxidant capacities of the chelators with a solubility of more than 150 mg/mL in water were examined through UV-vis spectroscopy by determining their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activities. Results revealed that these chelators may be used for complexation, antioxidant activity, and radionuclide decorporation.

Controllable synthesis of flower-like MoSe2 3D microspheres for highly efficient visible-light photocatalytic degradation of nitro-aromatic explosives

Nitro-aromatic explosives existing on the surface of the Earth are difficult to degrade, and they greatly harm the ecological environment and human security. Herein, we successfully conducted the large-scale synthesis of novel flower-like MoSe2 3D microspheres and nanospheres by a simple hydrothermal method. The two types of MoSe2 3D spheres had a high crystal quality with abundant nanosheets, and their diameters were approximately 1.5 μm and 300–400 nm, respectively. The Brunauer–Emmett–Teller (BET) and UV-vis diffuse reflectance spectra (UV-vis DRS) analyses revealed that the specific surface area and the band gap of MoSe2 microspheres and nanospheres were 33.3 m2 g−1 and 1.68 eV and those of the nanostructures were 13.6 m2 g−1 and 1.52 eV, respectively. Moreover, two different morphologies of MoSe2 were used for the degradation of nitrobenzene (NB), p-nitrophenol (PNP) and 2,4-dinitrophenol (2,4-DNP) through a photocatalytic process. The results demonstrated that the three nitro-aromatic explosive solutions NB, PNP and 2,4-DNP (40 mg L−1) could be completely degraded by MoSe2 3D microspheres under visible-light irradiation in 3.5 h, 1.5 h and 2.5 h, and the degradation time for MoSe2 nanospheres was 4.5 h, 2.5 h and 4 h, respectively. The mechanism of the photocatalytic reaction was also investigated in detail, and the photocatalytic degradation process was found to follow the pseudo-first-order kinetics. Our study demonstrated the potential application of MoSe2 microspheres as a photocatalyst for the degradation of nitro-aromatic explosives and other organic contaminants.

Synthesis, Crystal Structure and Thermal Decomposition of Triaminoguanidinium 2, 4, 6-Trioxo-1, 3, 5-triazinan-1-ide Based on Cyanuric Acid

A nitrogen-rich energetic compound-triaminoguanidinium 2, 4, 6-trioxo-1, 3, 5-triazinan-1-ide (1) was prepared with a yield of 91% via one-step metathesis reaction using triaminoguanidinium hydrochloride (TAG-HCl) and sodium cyanurate (CANa) as raw materials. The structure of the product was characterized by X-ray single-crystal diffraction, UV-Vis, FT-IR, 1H NMR, mass spectrometry and elemental analysis. The enthalpy of formation and detonation parameters of the product were calculated. Its thermal stability, non-isothermal reaction kinetics and decomposition process were studied by differential scanning calorimetry(DSC) at a heating rate of 10 K·min-1 and thermogravimetric (TG) analysis coupled with Fourier transform infrared spectroscopy (FTIR). The impact sensitivity of the product was determined by the drop hammer test. Results show that the crystal of compound 1 is monoclinic, space group P21/n with a calculated density of 1.676 g·cm-3. Its enthalpy of formation is 327.9 kJ mol-1, the detonation velocity 7900 m·s-1, and the detonation pressure 26.5 GPa. Probable thermal decomposition mechanism of 1 under N2 atmosphere as shown in the text is proposed. Compound 1 is very insensitive to impact, and the impact sensitivity is greater than 60 J, which is better than that of TATB (50 J).