2,4,4,6,8,8-Hexanitro-2,6-diazaadamantane: A High-Energy Density Compound with High Stability

Synthesis of a 2,4,6,8-Tetraoxaadamantane-Based 3D Energetic Biocidal Agent via Stepwise Cyclization Strategy

A cage-like iodine-containing energetic biocidal agent 9,10-bis(nitratomethyl)-9,10-diiodo-2,4,6,8-tetraoxaadamantane was designed and synthesized through a stepwise cyclization strategy via only five steps with a total yield of 13%. It has a high density, perfect oxygen balance, and moderate detonation properties. Its decomposition products exhibit excellent antibacterial properties. These results imply that it has the potential to be used as an energetic biocidal agent.

Computational Access to 1,3,5,6,7-Pentanitro-3,6,7-Triazabicyclo-[3.1.1]-Heptane (UIX): A Powerful Potential Explosive with Zero Oxygen Balance

A novel cage nitramine, and potential explosive, 1,3,5,6,7-pentanitro-3,6,7-triazabicyclo-[3.1.1]-heptane (UIX) with a zero-oxygen balance was designed. It has a high crystal density (ρ = 1.978 g/cm3), and outstanding propulsive and detonation properties (Isp(s)neat = 269.61; ρIsp(g cm-3 s)neat = 533.29; P = 42.55 GPa, D = 9620 m/s), with good sensitivity (h50 = 9.06 cm) and promising kinetic stability as CL-20. Additionally, a synthesis route for UIX is proposed.

Construction of an All-Bridge Carbon-Oxidized 2-Azaadamantane Skeleton and Synthesis of Two Energetic Derivatives

The construction of an all-bridge-oxygenated (hetero)adamantane skeleton is a long-standing challenge. Herein, an all-bridge carbon-oxidized 2-azaadamantane skeleton, 6,9,10-trimethoxy-2-azaadamantane-4,8-diol, was constructed via an eight-step synthetic route from 9-hydroxybicyclo[3.3.1]nonane-2,6-dione with an overall yield of 45%. The obtained skeleton was derived into two novel high-performance energetic compounds. Among them, 2,9,9,10,10-pentanitro-2-azaadamantane-4,6,8-triyl trinitrate is the first example that possesses eight explosophoric groups on the adamantane skeleton.

Computational study of nitrogen-rich hexaazaadamantane cage compounds as potential energetic materials

CONTEXT

Nitrogen-rich carbocyclic cage compounds serve as versatile platforms for the design and development of explosives with tailored properties. Their compact and rigid structure due to efficient packing leads to high crystal density. Moreover, their structural characteristics and amenability to functionalization make them indispensable in the quest for more powerful and efficient energetic materials. Adamantane derivatives are promising candidates for high-energy materials due to their unique molecular structure and the ability to introduce explosophoric groups onto their scaffold. In this computational study, we investigated the effects of substitution of six different explosophoric groups on the hexaazaadamantane skeleton. We explore the incorporation of - N(O)- NNO2, - N(O)- NCN, - N3, - ONO2 - NO2, and - NH2 functionalities, renowned for their high-energy content and ability to enhance explosive properties. We predict the electronic structure, heat of formation, thermodynamic stability, impact sensitivity, and detonation performance of these azaadamantane derivatives. The results indicate that the nitrogen-rich adamantane-based cage structure, featuring - ONO2 functional groups along with - NH2 groups, exhibits excellent explosive properties and good impact sensitivity. Our computational approach enables the screening and design of novel energetic materials with superior explosive properties, offering insights into structural modifications that optimize energy release, sensitivity, and detonation characteristics.

METHODS

Density functional theory (DFT) using the Gaussian 16 software was used for all quantum chemical calculations. The optimization of the geometry of the designed compounds is performed at two different levels, e.g., B3LYP/6-311 + + G(d,p) and B3PW91/6-31G(d,p). Molecular surface and other properties are visualized using the Gaussview 6.0 software. The heat of formation (HOF) of the molecules is estimated using isodesmic reactions. The Multiwfn program was used for the calculation of molecular surface properties.

Unveiling the energetic potential of azahomocubane (AHC): a new class of potential propellants, explosives and oxidizers

Cage compounds are potential kinetic rocks and thermodynamic powerhouses. Their strain energy plays a crucial role. Hence, adamantane, cubane, homocubanes, and bishomocubane skeletons have become prominent recently. However, research on the design and development of azahomocubane-based energetic materials has yet to be explored. The aim of the present work is to illustrate the potential of azahomocubanes as next-generation propellants, explosives and oxidizers. The energetic potential of any new materials was determined using B3LYP/6-31+G**, G2, and MP2/6-311++G** levels at the Gaussian 03 suite of programs. The new azahomocubanes possess a density range of 1.33 g cm-3 to 2.14 g cm-3. Most of the azahomocubanes have significantly elevated high-positive heats of formation ( to 728.41 kJ mol-1). Compounds AHC-12-19 have superior potentials as solid propellants in rocket propulsion. Additionally, this study reveals that compounds AHC-20 and AHC-21 could be highly effective primary explosives (AHC-20, P = 44.46 GPa, D = 9706 m s-1; AHC-21, P = 45.64 GPa, D = 9708 m s-1) exceeding the performance of RDX, HMX and comparable to that of ONC and CL-20. Our finding suggests that azahomocubanes have great potential in the field of energetic materials.

Synthesis, Characterization and Energetic Properties of Hydroxymethyl-Bishomocubanone Derivatives

The present work reports synthesis, characterization and theoretical insights on novel hydroxymethyl-bishomocubanone derivatives. Twelve new bishomocubanes (BHCs) were synthesized and fully characterized by various spectroscopic techniques and single crystal X-ray analysis. The densities of the title compounds were in the range of 1.30-1.59 g/cm3. Density-functional theory (DFT) based calculations at B3LYP/6-311++G(d,p) level of theory were performed on ten selected BHC based cage compounds. Propulsive and ballistic properties of newly synthesized hydroxymethyl-bishomocubanone derivatives in solid and liquid propulsion systems were calculated, and the results suggested that these compounds are superior to conventional fuel RP1 and binder HTPB. The detonation parameters revealed that these compounds are not explosive in nature and safe to use as solid propellants. Furthermore, kinetic and thermal stabilities of the title compounds were determined by HOMO-LUMO energy gap, ESP maps, impact sensitivity (h50) and bond dissociation energies (BDEs) followed by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Three compounds, a dinitroazide (Isp,vac=310.98 s), a dinitrate (Isp,vac=309.51 s), and a dinitronitrate (Isp,vac=309.20s) were found to be excellent candidates for volume limited applications.

Approaches to 1,4-Disubstituted Cubane Derivatives as Energetic Materials: Design, Theoretical Studies and Synthesis

Novel 1,4-disubstituted cubane derivatives have been designed and selected ones have been successfully synthesized and characterized by various analytical and spectroscopic techniques, including single-crystal X-ray analysis. A detailed computational study at B3LYP/6-311++G(d,p) level of theory revealed that all newly designed 1,4-disubstituted cubane derivatives possess higher densities, higher density-specific impulse and superior ballistic properties when compared to conventional fuels, for example, RP-1. These compounds also exhibit acceptable kinetic and thermodynamic stabilities which were evaluated in terms of their HOMO-LUMO energy gap and bond dissociation energies, respectively, and are superior to TEX and many other compounds containing explosophoric groups. These results provide novel insights into the possible application of cubane-based energetic materials.

Facile construction of the all-bridge-position-functionalized 2,4,6,8-tetraazaadamantane skeleton and conversion of its N-functionalities

An unusual protocol of a “one-pot” three-step strategy to build the 2,4,6,8-tetraazaadamantane skeleton was developed. 17 products were obtained in 19–46% yields, and the N-benzyl groups were transferred to nitroso, acetyl, benzoyl and nitro groups.

Design and Computational Insight on Two Novel CL-20 Analogues, BNMTNIW and BNIMTNIW: High Performance Energetic Materials

In this study, a theoretical Insight into two newly designed novel CL-20-based high performance energetic compounds, namely bis(nitromethyl)-tetranitrohexaaza-isowurtzitane (BNMTNIW) and bis(nitratomethyl)-tetranitrohexaaza-isowurtzitane BNIMTNIW), is reported. The title compounds are expected to...

Accelerating Molecular Design of Cage Energetic Materials with Zero Oxygen Balance through Large-Scale Database Search

Domain-related knowledge promoted high-throughput cage scaffold screening from the ZINC15 database containing over 130 000 scaffolds and cooperated with combinatorial design to alleviate the lack of cage energetic materials. A dozen candidates were discovered that show excellent energy and safety performance, confirming the effectiveness of our strategy.

7-Meth-oxy-penta-cyclo-[5.4.0.02,6.03,10.05,9]undec-ane-8,11-dione

The structure of 7-meth-oxy-penta-cyclo-[5.4.0.02,6.03,10.05,9]undecane-8,11-dione, C12H12O3, at 150 K has monoclinic (P21/c) symmetry. The penta-cyclo-undecane cage compound is composed of four five-membered rings, a planar four-membered ring and a six-membered ring in a boat conformation fused into a closed strained-cage framework. All of the five-membered rings adopt an envelope conformation.

Supramolecular Approach to Electron Paramagnetic Resonance Distance Measurement of Spin-Labeled Proteins

We demonstrate a host-guest molecular recognition approach to advance double electron-electron resonance (DEER) distance measurements of spin-labeled proteins. We synthesized an iodoacetamide derivative of 2,6-diazaadamantane nitroxide (DZD) spin label that could be doubly incorporated into T4 Lysozyme (T4L) by site-directed spin labeling with efficiency up to 50% per cysteine. The rigidity of the fused ring structure and absence of mobile methyl groups increase the spin echo dephasing time (T_m) at temperatures above 80 K. This enables DEER measurements of distances >4 nm in DZD-labeled T4L in glycerol/water at temperatures up to 150 K with increased sensitivity compared to that of a common spin label such as MTSL. Addition of β-cyclodextrin reduces the rotational correlation time of the label, slightly increases T_m, and most importantly, narrows (and slightly lengthens) the interspin distance distributions. The distance distributions are in good agreement with simulated distance distributions obtained by rotamer libraries. These results provide a foundation for developing supramolecular recognition to facilitate long-distance DEER measurements at near physiological temperatures.

Energetic materials with fluorinated four-membered heterocyclic ring: 3,3′-difluoroazetidine (DFAZ) salts

Fluorine atoms and four-membered rings form 3,3′-difluoroazetidinium (DFAZ) salts, which have a better detonation property than ammonium dinitramide (ADN).