Theoretical And Synthetic Study Of Bicyclic Furazan Energetic Compounds

Furazan compounds with high energy and high density are a hot research topic in the field of energetic materials.The interconnected bicyclic compounds are characterized by many derivative sites and highly conjugated structure,and the use of these compounds as the parent can promote the effective improvement of the overall energy of the molecule.In this paper,72 bicyclic furazan compounds were designed and their energetic properties and stability were investigated by using density functional theory（DFT）,focusing on the synthesis and performance study of C5 compounds and derivatives.A global search using molecular mechanics method（MM）was performed to predict the best crystal conformation of the compounds.The main studies are divided into three parts as follows:（1）Based on the bicyclic system of 4,4’-dinitroamino-3,3’-difurazan,four bicyclic interconnected structures were designed as energetic skeletons with furazan as the skeleton and subjected to primary screening.Using DFT theory at the level of B3LYP/6-311G**,two excellent backbones were screened for site-modification using HOF and detonation performance as the main evaluation criteria,and 72 titled compounds were constructed and their energetic properties and stability were examined.Among these compounds,B4,C2 and L4 have the optimal detonation velocity and detonation pressure and BDE,and five titled compounds were selected by considering the detonation performance and stability of the compounds.（2）For the screened compound C5,the target compounds and their energetic salts（A～K）were synthesized by dehydration off-ring,nitration and neutralization reactions using malononitrile as raw material,their structures were characterized by IR and NMR,and their thermal stability were investigated by using DSC.The synthesized nitrogen-rich heterocyclic energetic salts（G～J）were focused on single-crystal incubation and structural confirmation,and the sensitivity of C5 and G～K,both of which belong to blunt explosives（IS>40 J）,were tested using drop hammer experiments.The intermolecular interactions of G～J were illustrated in combination with Hirshfeld surface analysis and other means,and the results showed that all four energetic salts have strong hydrogen bonds andπ-πinteractions,which make them highly stable.（3）The molecular stacking mode,i.e.,the space group to which the five compounds obtained from the filtering were predicted under the Dreiding force field using the Materials Studio program,and it was found that the space group of several compounds was P2₁/c except for L4,which belonged to P-1;the energy gap difference(ΔE_LUMO-HOMO)and electrostatic potential（ESP）values of the above compounds were calculated and their relationship with stability was evaluated.