Cage Compounds And Three-membered Ring Compounds Are Studied As High Energy Density Materials

High energy density compounds (HEDCs) have attracted manyattentions for their bright usage prospect in the fields of fuel,explosives and propellants. In the last decades, extensivetheoretical studies have been performed on pure-nitrogen clustersas HEDCs in that all-nitrogen molecule Nxcan undergo the reactionNxâ†'(x/2) N2, a reaction that can be exothermic by50kal.mol-1ormore per nitrogen atom. However, theoretical studies have shownthat numerous Nxmolecules are not sufficiently stable and theycannot be readily synthesized to be practical HEDCs. Besides thepure-nitrogen clusters, other some heterocyclic compounds andcaged molecules have also attracted considerable attention. Thecharacteristic feature of such compound is high density, goodoxygen, and good thermal stability. As the HEDCs, experimentalsynthesis is not only dangerous but also hazardous to humans andthe environment. However, computer simulation, an effective way inscreening promising explosives without these shortcomings, hasbeen used to design various new energetic materials. Therefore, tomake a breakthrough in HEDCs research, it is a key step to makemolecular design and to synthesize new and excellent HEDCs.In this paper, the three type compounds have been studied usingquantum chemistry method in our work, we design the isoseismic reactions, in which the basic structural keeps invariable, and thebig molecules are changed into small ones, to obtain HOFs. Thedetonation velocity and pressure are obtained by theKamlet-Jacobs equation. The thermal stabilities of the titlecompounds were evaluated by calculating BDE of the trigger bond,which is judged according to the principle of the smallest bondorder and Mulliken population analyses. These calculations canprovide basic information for synthetic chemistry.1Prismane derivativesThe geometries of33prismane derivatives are fully optimizedusing the density functional theory at the B3LYP level with the6-311G**basis set. These results show that all derivatives havehigh and positive heats of formation, and there is a good linearrelationship between heats of formation and the number ofsubstituent group. Thus, the contributions of the substituentgroups to the HOFs clearly comply with the group additivity rule.The calculated bond dissociation energies calculations show thatC-NO2bond should be the trigger bond in the pyrolysis process forpolynitroprismane. However, for polynitramineprismane andpolynitrosoprismane, C-C bonds are considered as trigger bond.Considering the detonation performance and thermal stability, thepolynitroprismanes with five or six nitro groups meet the demandsof practical HEDC s, and can therefore be recommended ascandidates for HEDCs. Especially hexanitroprismane, thedetonation velocity and pressure are10.15m/s and48.61GPa,respectively.2Cubane derivatives All molecular structure s were optimized using the B3LYPmethod of density functional theory (DFT) and the6-311G**basisset. The computational results show that the energy gaps ofpolynitraminecubanes are much higher than that of TATB. Inaddition, the energy gaps of polynitraminecubanes can be affectedby the position of nitramine group. Polynitraminecubanes have highand positive HOF, and there is good linear relationship between HOFand nitramine group numbers. As the number of nitramine groups inthe molecule increases, the enthalpies of combustion values areincreasingly negative, but the specific enthalpy of combustionvalues decreases. The calculated bond dissociation energies ofC-NHNO2and C-C bond show that the C-C bond should be the triggerbond in the pyrolysis process. Heptanitraminecubane andoctanitraminecubane have detonation performance better thanHMX, and can be regarded as potential candidates of HEDCs.Analogous conclusion also can be obtained inpolydinitroaminocubanes system. In addition, oxygen balance isanother very important impact in increasing detonationperformance except density and detonation heats.3Nitro-triaziridines derivativesThe series of nitro-triaziridines have been studied as high energydensity compounds at B3LYP/6-311G**and MP2/6-311G**level byusing density functional theory. The bond dissociation energy of allcompounds meet the requirement as high energy compound atMP2/6-311G**level. However, only the bond dissociation energy ofA1is over80KJ/mol at B3LYP/6-311G**level. The result shows thatelectronic correlation has large effect for calculating bond dissociation energy. The explosive performances are calculated byK-J equation and specific impulse, but the two results are notconsistent. Therefore, we think that the K-J equation can not be usefor the compounds, which are only composed with N, H. O elements.Moreover, we also calculated the properties of ethylene oxidederivatives. The results show that all the ethylene oxide derivationshave good thermal stabilities, but their detonation performance cannot meet the demand as HEDCs.