Molecular Designing,Characterization And Performance Of HE-MOFs Based On (Tetrazole-Yl)-Furazan

HE-MOFs,as a kind of new materials,are quite popular in recent years,duing to their stable system,control structure,modified performance and so on.What's more,they generally have higher density,better thermal stability,excellent mechanical strength and hardness,etc.Thus,HE-MOFs have good application prospect and development potential.In this paper,we aimed at studying new HE-MOFs with higher energy and lower sensitivity,and the main research content includes the following two parts:First,we synthesized the energetic ligand,3-amino-4-(tetrazolate-5-ly)-furazan,which has higher nitrogen content(N%=64.05%)and strong coordination ability.Then,we chose Cd as central metal ion,and did the molecular design and synthesized different dimensions of HE-Cd-MOFs based on the theory of coordination chemistry.Three new crystals have been gotten through solvent evaporation method,they are NH4AFT?[Cd(H2O)2(AFT)2]n and[Cd(N2H4)(AFT)2·0.7H2O]n.The crystal structures of HE-Cd-MOFs have been characterized by X-ray single crystal diffraction.The coordination way between HAFT and Cd has been cleared.Among them,[Cd(H2O)2(AFT)2]n belongs to monoclinic system,space group of P21/c,a 2D MOFs and plane structure,and its crystal density is as high as 2.252 g·cm-3.On the basis of the structure of[Cd(H2O)2(AFT)2]n,the design scheme of[Cd(NH2NH2)2(AFT)2·0.7H2O]n has been made to construct more complex Cd-HE-MOFs crystal structure,replacing the the coordinated water molecules of[Cd(H2O)2(AFT)2]n by N2H4.However,[Cd(N2H4)(AFT)2·0.7H2O]n belongs to monoclinic system,space group of C2/c,a 1D MOFs and chain structure,and its crystal density is 2.026g·cm-3,which is lower than[Cd(H2O)2(AFT)2]n.That might caused by the bond length of N2H4 is not enough to construct 3D structure.What's more,the thermal decomposition behavior of them has been study by differential scanning calorimetry(DSC),and the non-isothermal kinetic parameters and the thermal explosion critical temperature of them have been calculated.Through the comparison,we found that[Cd(N2H4)(AFT)2·0.7H2O]n(Td=308.5?,?=10?.min-1)has the best thermal stability.By analysizing the effect of structure on performance,the excellent thermal stability of[Cd(N2H4)(AFT)2·0.7H2O]n may due to the reinforced structure of it,in which N2H4 connected two Cd2+ again in the pore of chain structure bridging by Cd2+ and AFT-.Second,we chose Zn and Cu as central metal ion to replace the Cd,because of its harmful nature as one of heavy metals.Then,we designed and synthesized HE-Zn/Cu-MOFs in order to get green HE-MOFs.Also,the thermal decomposition behavior of them has been study by differential scanning calorimetry(DSC),and the non-isothermal kinetic parameters and the thermal explosion critical temperature of them have been calculated.The exothermic peak of HE-Zn-MOFs is not obvious,but its thermal stability is better than HE-Cu-MOFs.In this research,the HE-MOFs with HAFT as energetic ligand,both showed good thermal stability,and exhibited lower impact sensitivity(>40 J).And their structure can be designed in different dimensions.So,we concluded that thess class of HE-MOFs have great research value in the energetic material material field pursuiting high energy and low sensitivity.