Energetic norbornenes are promising candidates toward the development of new energetic polymers due to the synthetic versatility of norbornene ring-opening metathesis polymerizations used in commercial applications. We report the synthesis of two energetic norbornene materials that can be made in two steps with modest yields, containing either trinitroethanol or fluorodinitroethanol substituents. The norbornene monomers were then polymerized, and the polymers were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), contact angle measurements, and proton and carbon nuclear magnetic resonance spectroscopies (1H and 13C-{1H} NMR). Additionally, small-scale safety data consisting of electrostatic discharge (ESD), friction (FS), and impact (IS) sensitivities were measured for the norbornene monomers and their resulting polymers. These analyses revealed that energetic norbornene materials are relatively insensitive and have densities comparable to that of TNT (1.47-1.81 g·cm-3).

The synthesis and characterization of several TATB-inspired energetic materials was explored. Despite their structural similarity to TATB, their behavior toward traditional synthetic pathways deviates significantly from that of the parent material. This change in expected reactivity is discussed and an efficient alternative synthesis is reported. The development of a simple and effective route to these TATB-type compounds opens the door to a potential new class of insensitive high explosives.

Energetic plasticizers are being sought for their use in energetic formulations when combined with explosives. An energetic plasticizer based on the insensitive highly explosive 3-amino-5-nitro-l,2,4-triazole (ANTA) was synthesized and characterized by spectroscopy, X-ray crystallography, thermal analyses, and safety testing. Lastly, density functional theory calculations were employed to examine the observed selectivity among the three nucleophilic ring nitrogen atoms of ANTA toward electrophiles such as ANTA acrylate; this selectivity was found to be a combination of steric, electronic, and hydrogen bonding effects.

3,4- and 3,5-Dinitropyrazoles (DNPs) were substituted with acryl and allyl groups on the N1 nitrogen atom, resulting in three novel energetic materials. These compounds are all liquids at room temperature with melting points ranging from -60.2 to -38.6 °C and were fully characterized by high-resolution mass spectrometry, elemental analysis, proton and carbon nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. These materials were also tested for electrostatic discharge, friction, and impact sensitivities and then compared to DNP starting materials and to the explosive nitroglycerin (NG). These results indicate that the synthesized compounds are less sensitive to impact compared to NG and have higher thermal stabilities to decomposition.

An energetic nitrate ester acrylate monomer (4) was synthesized in a total yield of 68% and polymerized to form the energetic nitrate ester acrylate polymer (NEAP). Compound 4 is a liquid at room temperature with a melting point of -8.6 °C and NEAP is a solid with a glass-transition temperature of -8.8 °C. Intermediates leading to 4 and NEAP were characterized by high-resolution mass spectrometry, elemental analysis, Fourier transform infrared spectroscopy, and proton and carbon nuclear magnetic resonance spectroscopies (1H and 13C{1H} NMR). Both 4 and NEAP have electrostatic discharge, friction, and impact sensitivities comparable to those of trinitrotoluene, making NEAP a potential candidate for advanced energetic formulations.

High nitrogen compounds find wide use in the development of new propellants and explosives as well as pharmaceutical chemistry as bioisosteres, bacterial stains, and antifungal agents. A class of underexplored high-nitrogen materials includes azidoximes and their 1-hydroxytetrazole isomers. Azidoximes possess an energetic azide group and are quite sensitive to impact, spark, and friction. Therefore, these materials are generated in situ and cyclized under mild acidic conditions to their 1-hydroxytetrazole isomers. Recently, we synthesized a novel 1,2,4-triazine-derived azidoxime; however, upon subjecting this material to established cyclization conditions, no reaction was observed, even after prolonged reaction times with heating. Additional 1,2,4-triazine-derived azidoximes also displayed a similar lack of reactivities. This observation led us to probe the reactivity of these materials with both a DFT investigation and crystallographically based electrostatic potential mapping. In all, the lack of reactivity toward cyclization was found to be due to an inability of 1,2,4-triazine-based azidoximes to isomerize into the reactive (E)-conformation, requiring an activation energy of 26.4 kcal mol-1.

We report a [3+2] cycloaddition using 3,6-bis-propargyloxy-1,2,4,5-tetrazine and azides to synthesize energetic polymers containing 1,2,4,5-tetrazine within the scaffold. This work also includes [3+2] cycloaddition to crosslink azide containing glycidyl azide polymer (GAP). These reactions provide pathways for incorporation of 1,2,4,5-tetrazine into novel energetic materials using click-chemistry and provide an alternative polymer curing approach.

A 1,2,4-triazine based azidoxime was formed via the substitution of a chloroxime (3) with sodium azide in ethanol. This compound was characterized via single-crystal X-ray diffraction. This material has a calculated density of 1.746 g.cm(-3) and is less sensitive to impact, spark, and friction, as compared to PETN and RDX. The dehydrated material has a calculated density of 1.823 g.cm(-3) and the detonation pressure and velocity of 4 are calculated to be 29.1 GPa and 8.67 km.s(-1), respectively.

A 1:2 cocrystal of 4H,8H-difurazano[3,4-b:3',4'-e]pyrazine and hydroxylamine has been prepared that displays 1,3,5-triamino-2,4,6-trinitrobenzene-like sensitivity and performance. Most notably, the detonation properties of the cocrystal are better than that of the hypothetical 1:2 physical mixture and also higher than the theoretically predicted salt, making this a rare example of a cocrystal in which the detonation properties are synergistic. This was achieved through maximizing the intermolecular interactions through several hydrogen bonding and pi-stacking.

Spin crossover complexes are known to undergo bond length, volume, and enthalpy changes during spin transition. In an explosive spin crossover complex, these changes could affect the mechanical and initiation sensitivity of the explosive and lead to the development of a new class of sensitivity switchable materials. To explore this relationship, the well-known spin crossover compound [Fe(Htrz)(3)](n)[ClO4](2n) (1) was re-evaluated for its explosive properties, and its mechanical impact sensitivity was correlated to spin transition. A variable temperature impact test was developed and used to evaluate the impact sensitivity of 1 in the low spin (LS, S = 0), thermally accessed high spin (HS, S = 2), and mixed LS and HS states. For comparison, the structurally similar Ni compound, [Ni(Htrz)(3)](n)[ClO4](2n) (2), which does not undergo a spin transition at accessible temperatures, was synthesized and characterized, and its explosive properties and variable temperature impact sensitivity measured. These results reveal a correlation between impact sensitivity and spin transition, where 1 exhibits lower impact sensitivity in the LS state and increases in sensitivity upon transition to the HS state. Density functional theory was used to predict structural changes that occur upon spin transition that correlate to the change in sensitivity. This demonstrates, for the first time, an explosive spin crossover compound (ExSCO) that exhibits switchable impact sensitivity with a fully reversible internal switching mechanism.

The synthesis and crystal structure of the heterocyclic explosive bis(nitroxymethylisoxazolyl) furoxan, C10 H6 N6 O10 , are described. In addition, we report its physical properties and theoretical performance. This material was found to exhibit standalone melt-castable explosive properties, with a melting point of 89.8 °C and an onset decomposition temperature of 193.8 °C. Bis(nitroxymethylisoxazolyl) furoxan features an insensitive behavior to impact, friction, and electrostatic discharge, with a calculated detonation pressure about 25 % higher than the state-of-the-art melt-castable explosive TNT.

Enhanced safety, with the ability to control detonation behavior, while maintaining energy output are highly desirable characteristics for new high explosive (HE) materials. The use of switchable explosive spin crossover (ExSCO) compounds is a potentially powerful strategy to access on-demand mechanical sensitivity. Spin crossover is a transition between the low spin (LS) and high spin (HS) state electron configurations in a metal complex. We present our variable temperature impact sensitivity results on [Fe(Htrz)3]n[ClO4]2n, a high nitrogen Fe(II) ExSCO compound, and compare its mechanical sensitivity in the LS vs HS states. In addition, we describe the synthesis and properties of energetic acrylate monomers that will be used to develop custom materials for use in the additive manufacturing of explosives.

Understanding the factors that affect explosive sensitivity is paramount to the safe handling and development of new explosives molecules. Erythritol tetranitrate (ETN) is an explosive that recently has attracted significant attention in the explosives community because of its ease of synthesis and physical properties. Herein, we report the synthesis of ETN derivatives using azide, nitramine, and nitrate ester functional groups. Impact, spark, and friction sensitivity measurements, computationally calculated explosive properties, and the crystal structure analysis of the ETN derivatives are reported. Mixing explosive functional groups led to changes in the explosive sensitivity, explosive performance as well as physical properties including melting point and physical state at room temperature. Overall, we have demonstrated that combining functional groups can enable the tuning of explosive and physical properties of a molecule. This tunability can potentially aid in the development of new explosives in which characteristics are varied to meet certain specifications.

Understanding the factors that contribute to explosive sensitivity is key to developing new explosives. Explosive sensitivity is controlled by multiple factors some of which include crystal packing, hydrogen bonding and co- crystallization. Explosive functional groups impart a chemical effect towards explosive sensitivity due to different functional groups having different thermodynamic stabilities and decomposition methods. Herein we report the synthesis of erythritol and pentaerythritol complexes functionalized with nitrate esters, nitramines and azides. Six molecules were synthesized (two literature reported, four new complexes) and their explosive sensitivity was compared to ETN and PETN using impact, spark and friction sensitivity measurements. The molecules synthesized were a mixture of solids and liquids leading to questions about the effects of physical state on explosive sensitivity. These molecules were compared to our recent study on the impact sensitivity of molten ETN. Stereoisomers of ETN were synthesized to compare with liquid samples at room temperature. We observed that by mixing functional groups of varying sensitivity we were able to tune the explosive sensitivity of the molecule. Additionally, we observed liquid explosives with higher sensitivities than solid explosives, as to be expected due to their differing modes of initiation for liquid vs. solid explosives. These results suggest functionalization of known explosive frameworks can be used to tune explosive sensitivity due to changes in both chemical and physical properties of the molecules.

Metal nitrides are strong refractory ceramic materials known for applications in the coatings, catalysis, and semiconductor industries. Lanthanide nitrides are difficult to prepare in high purity and often require high temperatures and sophisticated equipment. In this work, we present an approach to the synthesis of high-purity f-element nitrides through the use of simple lanthanide salts and the nitrogen-rich ligand 5,5'-bis(1H-tetrazolyl)amine (H(2)BTA) to form lanthanide complexes of 5,5'-bis(tetrazolato)amine (BTA(2-)). We have demonstrated that, when dehydrated, these types of complexes undergo a self-sustained combustion reaction under an inert atmosphere to yield nanostructured f-element nitride foams for lanthanum and cerium. The synthesis, characterization, and single-crystal X-ray crystallography of the BTA(2-) complexes of lanthanum, cerium, praseodymium, neodymium, and europium are also discussed.

Understanding explosive sensitivity is key to the safe handling and development of new explosives. Macro- and microscale studies have concluded that multiple physical and chemical factors affect sensitivity, both intermolecular and intramolecular. Stereoisomers are molecular pairs with the same bond connectivity but differing spatial arrangement of those bonds, and in certain cases can exhibit vastly different chemical and physical properties. Herein we report the synthesis of stereoisomers of erythritol tetranitrate (ETN) and the reported stereoisomers mannitol hexanitrate (MHN) and sorbitol hexanitrate (SHN). Isomers of ETN and MHN had altered physical properties such as melting point, state of matter, and crystal structure. These different physical properties caused changes in the impact sensitivity of the isomers. The melting point of the explosive was determined to be a key factor in the impact sensitivity measurements, altering the physical state of the explosive at room temperature or by potentially facilitating access to the more sensitive liquid state of the explosive.