Nitrogen‐Rich Energetic Ionic Liquids Based on the N , N ‐Bis(1 H ‐tetrazol‐5‐yl)amine Anion – Syntheses, Structures, and Properties

π-Electronic ion pairs: building blocks for supramolecular nanoarchitectonics viaiπ-iπ interactions

The pairing of charged π-electronic systems and their ordered arrangement have been achieved by iπ-iπ interactions that are derived from synergetically worked electrostatic and dispersion forces. Charged π-electronic systems that provide ion pairs as building blocks for assemblies have been prepared by diverse strategies for introducing charge in the core π-electronic systems. One method to prepare charged π-electronic systems is the use of covalent bonding that makes π-electronic ions and valence-mismatched metal complexes as well as protonated and deprotonated states. Noncovalent ion complexation is another method used to create π-electronic ions, particularly for anion binding, producing negatively charged π-electronic systems. Charged π-electronic systems afford various ion pairs, consisting of both cationic and anionic π-systems, depending on their combinations. Geometries and electronic states of the constituents in π-electronic ion pairs affect the photophysical properties and assembling modes. Recent progress in π-electronic ion pairs has revealed intriguing characteristics, including the transformation into radical pairs through electron transfer and the magnetic properties influenced by the countercations. Furthermore, the assembly states exhibit diversity as observed in crystals and soft materials including liquid-crystal mesophases. While the chemistry of ion pairs (salts) is well-established, the field of π-electronic ion pairs is relatively new; however, it holds great promise for future applications in novel materials and devices.

Designing high-performance hypergolic propellants based on materials genome

A new generation of rocket propellants for deep space exploration, ionic liquid propellants, with long endurance and high stability, is attracting more and more attention. However, a major defect of ionic liquid propellants that restricts their application is the inadequate hypergolic reactivity between the fuel and the oxidant, and this defect results in local burnout and accidental explosions during the launch process. We propose a visualization model to show the features of structure, density, thermal stability, and hypergolic activity for estimating propellant performances and their application abilities. This propellant materials genome and visualization model greatly improves the efficiency and quality of developing high-performance propellants, which benefits the discovery of new advanced functional molecules in the field of energetic materials.

Insensitive ionic bio-energetic materials derived from amino acids

Energetic salts/ionic liquids have received increasing attention as fascinating energetic materials, and the use of renewable compounds is a promising approach to developing energetic materials. Until recently, biomolecules have been used as raw materials to develop neutral energetic compounds, whereas research focused on ionic energetic materials obtained from natural bio-renewable frameworks is scarce. This work systematically investigates ionic bio-energetic materials (IBEMs) derived from sustainable natural amino acids. In addition to combustibility, high density, good thermal stability, and one-step preparation, these IBEMs demonstrated apparent hypotoxicity and insensitivity. Moreover, a theoretical examination was performed to explore their appropriate properties. The intriguing results of this study indicates that IBEMs are potential bio-based energetic materials.

Compounds based on 3-amino-4-(5-methyl-1,2,4-oxadiazol-3-yl)furazan as insensitive energetic materials

Insensitivity: Derivatives based on 3-amino-4-(5-methyl-1,2,4-oxadiazol-3-yl)furazan were synthesized and characterized. Most of these compounds are thermally stable and insensitive which make them competitive replacement as insensitive energetic materials.

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 (T_dec = 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.

Long-lived luminescent soft materials of hexanitratosamarate(III) complexes with orange visible emission

Sm(III)-based ionic liquids incorporating hexanitratosamarate(III) anions were obtained and fully characterized as novel Sm(III)-containing organic complexes. The structure of the ionic liquids was determined by single-crystal X-ray diffraction (1: monoclinic system C2/c space group with cell parameters: a = 19.5624(4) Å, b = 10.11895(18) Å, c = 33.2256(6) Å, β = 101.2912(18)°, Z = 8). The central Sm(III) ion is 12-coordinated by six bidentate nitrate ligands with twelve oxygen donors to form a [Sm(NO3)6](3-) anion. The low melting point, high thermostability and wide liquid range of these ionic liquids were determined in detail. All the complexes 1-5 display orange luminescence, rather than red luminescence as in most Sm(III)-containing organic complexes. Three characteristic monochromatic bands and an intense emission, derived from (4)G5/2→(6)HJ (J = 5/2, 7/2, and 9/2) intraconfigurational f-f transitions, were revealed. All these complexes exhibit long luminescence lifetimes.

Synthesis, structure and near-infrared photoluminescence of hexanitratoneodymate ionic liquids

Five hexanitratoneodymate-based rare earth complexes () were synthesized using a straightforward method. Purple plate crystals of were isolated and the crystal structure was determined by single-crystal X-ray diffraction with respect to the coordination mode of the nitrate anion to the central Nd(iii) ion. (: monoclinic system P21/c, a = 15.9460(3) Å, b = 10.2457(6) Å, c = 33.323(3) Å, β = 91.8108(17)°, V = 3109.11(11) Å(3), Z = 4). The central Nd(iii) ion is surrounded by six bidentate nitrate ligands, with a major trend towards high symmetry of the [Nd(NO3)6](3-) anion as an icosahedron. Thermal properties were determined from differential scanning calorimetry (DSC) combined with thermogravimetric analysis (TGA) tests. Complexes are found to be room temperature liquids, and their excitation and emission spectra were recorded. These complexes exhibit intense near-infrared (NIR) luminescence emission, which originates from interconfigurational f-f transitions (4)F3/2→(4)IJ multiplet (J = 9/2-13/2). These liquid Nd(iii) complexes are of interest as potential NIR luminescent soft materials with high thermal stability.

Insensitive energetic 5-nitroaminotetrazolate ionic liquids

Combustible 5-nitroaminotetrazolate-based energetic ionic liquids with high stability as well as environmentally friendly decomposition gases were prepared and fully characterized.

Electrochemical and thermodynamic properties of Ln(III) (Ln = Eu, Sm, Dy, Nd) in 1-butyl-3-methylimidazolium bromide ionic liquid

The electrochemical behavior and thermodynamic properties of Ln(III) (Ln = Eu, Sm, Dy, Nd) were studied in 1-butyl-3-methylimidazolium bromide ionic liquid (BmimBr) at a glassy carbon (GC) electrode in the range of 293–338 K. The electrode reaction of Eu(III) was found to be quasi-reversible by the cyclic voltammetry, the reactions of the other three lanthanide ions were regarded as irreversible systems. An increase of the current intensity was obtained with the temperature increase. At 293 K, the cathodic peak potentials of −0.893 V (Eu(III)), −0.596 V (Sm(III)), −0.637 V (Dy(III)) and −0.641 V (Nd(III)) were found, respectively, to be assigned to the reduction of Ln(III) to Ln(II). The diffusion coefficients (D_o), the transfer coefficients (α) of Ln(III) (Ln = Eu, Sm, Dy, Nd) and the charge transfer rate constants (k_s) of Eu(III) were estimated. The apparent standard potential (E⁰*) and the thermodynamic properties of the reduction of Eu(III) to Eu(II) were also investigated.