High‐Pressure Characterization of Melt‐Castable Biisoxazole Energetics: 3,3′‐Biisoxazole‐5,5′‐bis‐(Methylene) Dinitrate and 3,3′‐Biisoxazole‐4,4′,5,5′‐Tetrakis‐(Methylene Nitrate)

Abstract

The high‐pressure behavior of 3,3′‐biisoxazole‐5,5′‐bis‐(methylene) dinitrate (BIDN) and 3,3′‐biisoxazole‐4,4′,5,5′‐tetrakis‐(methylene nitrate) (BITN) have been studied at room temperature to 25 GPa by Raman spectroscopy and powder X‐ray diffraction. The Raman spectra, powder patterns, and calculated unit‐cell volumes at select pressures show qualitative agreement with first‐principles density function theory calculations. Over this pressure range, no evidence of polymorphism was observed. The lack of observed phase changes can be partially attributed to the strengthening of hydrogen bonding observed with pressure increase. These insights point to the potential importance of hydrogen bonding in potential melt‐castable materials.

High‐Pressure Characterization of Two Stereoisomers of Tetranitroester Cyclobutane

“…From the analysis of the P−V data, the following values for the bulk modulus ( B 0 ) and pressure derivative of ( B’ ) were derived: [cis‐trans‐cis] – B 0 =15.50±1.02 GPa and B’ =5.63±0.67, [all‐cis] – B 0 =11.65±0.26 GPa and B’ =6.22±0.18. These bulk modulus values are consistent with similar cyclic energetic molecules: BIDN (16.1±0.5/7.2), LLM‐105 (15±4/9±3), LLM‐172 (18.5±1.4/8.1), and DNDIF (14.9±0.9/6.7±0.6), respectively, for B 0 and B’ [7e, 8b–d]. The total volume compression upon increasing the pressure from ambient conditions to near 25.0 GPa was observed to be 32.9 % for [cis‐trans‐cis] and 38.9 % for [all‐cis].…”

“…The average peak shift value was 3.4 and 3.5 cm −1 GPa −1 for [cis‐trans‐cis] and [all‐cis], with ranges between 0.5 to 8.3 and 0.4 to 14.1 cm −1 GPa −1 , respectively for the two materials. These peak shift values are within the expected range for soft organic materials with applied pressure [7d, e, 8d, 13]. The largest frequency shift in [cis‐trans‐cis] (8.3 cm −1 GPa −1 ) and [all‐cis] (14.1 cm −1 GPa −1 ) occurs for the symmetric/asymmetric stretching of the C−H groups around 3050 cm −1 and may indicate a deformation of the methyl linkages.…”