It is of current development to construct high–performance energetic compounds by aggregation of energetic groups with dense arrangement. In this study, a hydrogen-free high-density energetic 3,4-bis(3-nitrofuroxan-4-yl)furoxan (BNTFO-I) was designed and synthesized in a simple, and straightforward manner. Its isomer, 3,4-bis(4-nitrofuroxan-3-yl)furoxan (BNTFO-IV), was also obtained by isomerization. The structures of BNTFO-I and BNTFO-IV were confirmed by single-crystal X-ray analysis for the first time. Surprisingly, BNTFO-I has a remarkable calculated crystal density of 1983 g cm⁻³ at 296 K, which is distinctly higher than BNTFO-IV (1.936 g cm⁻³, 296 K), and ranks highest among azole-based CNO compounds yet reported. It is noteworthy that BNTFO-I exhibits excellent calculated detonation properties (v_D, 9867 m s⁻¹, P, 45.0 GPa). The interesting configuration differences of BNTFO-I and BNTFO-IV provide insight into the design of new advanced energetic materials.

The crystal morphology of FOX-7 in different solvents was investigated via molecular dynamics simulations. A modified attachment energy (MEA) model was constructed by introducing surface chemistry terms and the associated topography of the habit crystal plane. Solvent has a large effect on the crystal morphology of FOX-7. The calculated results show that the crystal morphology of FOX-7 in vacuum is dominated by six faces, (0 1 1), (1 0 −1), (1 0 1), (1 1 −1), (0 0 2) and (1 10), while that in acetic acid is dominated by three faces, (1 1 −1), (0 1 1) and (1 0 1). The applicability of the model was successfully validated by the study of FOX-7 crystals grown from cyclohexanone, acetonitrile, H₂O/DMF, and H₂O/DMSO. All the predicted results are in good agreement with the experimental results. The crystal morphology of FOX-7 is variable in different crystallization solvents. H₂O/DMF and H₂O/DMSO are good choices for the solvent recrystallization of FOX-7. The results are useful for the formulation design of FOX-7.