Impact of Positional Isomerism on Melting Point and Stability in New Energetic Melt-Castable Materials

Abstract

For an energetic material with a definite composition, the substituent position is the most crucial factor to influence its physicochemical properties. Thus, it is becoming increasingly important to understand the impact of positional isomerism on multidimensional properties differences. Herein, we reported two new potential energetic melt-castable molecules, a pair of positional isomers (4-MMDNP and 5-MMDNP). These two explosives exhibit obviously different properties, including densities (Δρ = 0.03 g cm −3 ), melting point (ΔT m = 47.2 °C), decomposition temperature (ΔT d = 27.3 °C), stability (IS = 20 J, FS = 160 N vs IS = 10 J, FS = 40 N), etc., even though they share similar compositions and structures. Simultaneously, by analyzing crystal packing, intermolecular interactions, and monomolecular parameters, we were able to uncover the roots of property differences. Altogether, our results provide comprehensive molecular and crystal level insight into the effect of positional isomerism, which may be useful for new molecular design.

Insight into melting point differences of dinitroimidazoles and dinitropyrazoles from the perspective of intermolecular interactions

“…Building upon this approach, in our previous works, 17–20 we introduced a method known as binding energy in clusters (BEC). This approach involves using home-made scripts to decompose periodic crystals into molecular dimers and utilizes the SAPT method for calculating the interactions between these dimers (Fig.…”

Computational Manifestation of Nitro-Substituted Tris(triazole): Understanding the Impact of Isomerism on Performance-Stability Parameters

“…Shifting the −NO 2 and −CF 3 groups' position on the benzene ring resulted in a significant change in decomposition temperatures, energy content, and detonation properties (Figure 1j). Recently, Chen et al 33 reported 4methylnitramino-1-methyl-3,5-dinitropyrazole and 5-methylnitramino-1-methyl-3,4-dinitropyrazole melt-castable positional isomers. These isomers decompose at 187.8 and 160.5 °C, respectively.…”

Energetic bi-diazole ‘transformers’ toward high-energy thermostable energetic compounds

“…18–20 Recently, the tuning of the thermal stability and mechanic sensitivities of energetic compounds by isomerization through structural transformation has gained increasing attention in the field of energetic materials. 21–26 Various energetic compounds with improved properties have been designed and synthesized, in which alternative hydrogen bonding and crystal structure stacking could be obtained by group or skeleton transformation. As shown in Fig.…”