Assembly,Structures and Physicochemical Properties of Silver/Copper-based Energetic Coordination Compounds Constructed by Triazole/Tetrazole/Furazan Derivatives

Author:Qu Xiao Ni

Supervisor:chen san ping


Degree Year:2018





Compared to the conditional energetic materials,high-energy-density materials(HEDMs)with high energy and excellent insensitivity,play a significant role in military and civilian fields,and have become an important component of explosives,propellants and pyrotechnics.Based on coordination chemistry and crystal engineering,energetic coordination compounds have attracted increasing interest and occupy the important research potentials and practical significance.In this thesis,we focused on the study of the syntheses and physicochemical properties of energetic compounds.These energetic compounds with high energy and insensivity could be prepared by choosing the related triazole/tetrazole/furazan energetic ligands,aiming at investigating the relationship and the effect between these different energetic groups/skeletons/solvents and detonation performance.The main research contents are listed as follows:1.Syntheses,structures and physicochemical properties of Ag-based energetic coordination compounds with different energetic groups Two isostructural energetic coordination compounds,[Ag(atz)]n(1)and[Ag(ntz)]n(2)(Hatz=3-amine-1H-1,2,4-triazole,Hntz=3-nitro-1H-1,2,4-triazole),have been synthesized hydrothermally/solvothermally and structurally characterized.Crystal structure analyses reveal that in 1 and 2,the typical six-membered rings(Ag2N4)and sixteen-membered rings(Ag4N8C4)are linked each other to yield 2D planar layers.TG-DSC results show that 1 and 2 have high thermostability at 348 ℃ and 305 ℃,respectively.The precise oxygen bomb calorimeter(IKA C5000)was used to measure the constant-volume combustion energies of 1 and 2,based on which the standard enthalpies of formation were calculated to obtain the detonation parameters.The results illustrate that 2 displays the relatively excellent detonation performance with the heat of detonation 1.163 kcal g-1,the detonation velocity 7.938 km s-11 and the detonation pressure 36.47 GPa,respectively.2.Syntheses,structures and physicochemical properties of solvent-dependence Cu-based energetic compoundsAn energetic compound[Cu(ntz)]n(3)was prepared hydrothermally using Hntz as an energetic ligand.Then N3-was introduced into the reaction system to yield[Cu(ntz)(N3)(H2O)]n(4)and[Cu(ntz)(N3)(H2O)]n(5).Crystal structures show that ntz-adoptsμ3-1,2,4 mode in 3 to generate a 3D framework.4 and 5 are isostructural.N3-and ntz-ligands possess EO andμ2-1,2 modes respectively to bridge the neighboring Cu2+,producing 1D chains.TG-DSC results reveal that 3 is stable below 315.0 ℃,while 4 and 5 would decompose until 200 ℃ due to the coordinated DMF/H2O.3、4and 5 are all insensitive to impact and friction.4 has a relatively high heat of detonation mainly because of the coordination DMF molecules,which contains more C-N energetic bonds.Based on this,the coordinated solvent molecules play a critical effect on detonation performance.3.Synthesis of Ag-based energetic MOF constructed by 5-aminotetrazole and its catalytic performance for thermal decomposition of RDX A compact Ag-based 3D energetic MOF,[Ag2(5-ATZ)(N3)]n(6,ρ=3.38 g cm-3),was constructed hydrothermally.Crystal structure shows that 6 features 1D[Ag2(5-ATZ)]+chains and 2D[Ag2(N3)]+layers.TG-DSC results confirmed that 6 exhibited high thermal stability(Tdec=295.3 ℃).The compact 3D framework can effectively catalyze the thermal decomposition of RDX and decrease the thermal decomposition temperature of RDX down to 228.9 ℃.4.Syntheses,structures and physicochemical properties of Ag-based energetic compounds with different energetic skeletons According to the reported literatures,3,5-dinitro-1-H-1,2,4-triazole ammonium salts([2-ntz]?-[NH4]+)and 3,4-bis(1H-5-tetrazolyl)furoxan(H2BTOF)were synthesized.Then three energetic compounds,[Ag2(2-ntz)2]n(7),[Ag13(2-ntz)12(CH3CN)](NO3)}n(8)and[Ag2(BTOF)]n(9),were assembled solvothermally.Crystal structures indicate that 2-ntz-ligand adoptsμ3-1,2,4 coordination mode,and BTOF2-ligand adopts bridging and chelating modes to connect with Ag+,generating the stable framework.TG-DSC results show that 7 and 9 would decompose at 301.8 ℃ and 242.6 ℃,having high thermostability.7 exhibits outstanding detonation performance not only because of the contribution of-NO2,but also due to the stable and dense structure.5.Syntheses,structures and physicochemical properties of Cu-based energetic compounds self-assembled by post-synthesized approach Firstly 3,5-dinitroamino-1-H-1,2,4-triazole hydrazine salt([2-H2natz]?-[N2H5]+)was synthesized according to the literatures.Then an energetic compound,{[Cu2(2-natz)2(H2O)2]2-{[(CH3)2NH2]+}2}n(10),was generated solvothermally and structurally characterized,and finally[Cu3(2-natz)2(H2O)4]n(11)was obtained.Crystal structures show that two 2-natz3-ligands bridge and chelate two Cu2+centers in 10,forming[Cu2(2-natz)2(H2O)2]2-units.[(CH3)2NH2]+units from DMF are free as charge-balanced ions.Furthermore,[Cu2(2-natz)2(H2O)2]2-units are connected by[Cu(H2O)2]2+units,resulting in 1D chains of 11.TG-DSC results show that 10 and 11 begin to decompose around 200 ℃ due to the coordinated H2O molecules.10 and 11 are insensitive to impact and friction.10 has a relatively high heat of detonation,but the detonation velocity and detonation pressure are much low,revealing that the free energetic groups are also of importance for detonation performance.6.Syntheses,structures and physicochemical properties of porous Cu-based energetic compounds A porous energetic MOF,{[Cu(5-ATZ)]6?(H2O)}n(12),was prepared by 5-HATZ.In order to further increase the oxygen balance,p-carboxybenzaldehyde(4-HFBA)as auxiliary ligand was introduced and[Cu(4-FBA)(N3)}n(13)was obtained.In 12,5-ATZ-adoptsμ4-1,2,3,4 mode to connect with four different Cu+,forming porous hexagon[Cu(5-ATZ)]6 units.And there is a free H2O in this channel.In 13,N3-adopts EO mode to link the adjacent two Cu2+,producing 1D[Cu(N3)]+chains.4-FBA-as auxiliary ligand further connects 1D chains to generate 2D planes.TG-DSC results indicate that 12 and 13 have the relatively low thermostability with decomposition temperature about 100 ℃.12 and 13 are insensitive to impact and friction,but the detonation performance is unsatisfactory.Therefore,the influence of free solvent molecules and auxiliary ligands on detonation properties should not be ignored.