Synthesis,structure And Properties Of Energetic Coordination Polymer With Nitrogen-rich Ligands

Energetic coordination polymers,which have excellent explosive and safety properties,have become a hot research topic in the field of energetic materials.In this work,five energetic metal coordination polymers with nitrogen-rich ligands?H₂tza,Htza,N3-?and metal ions have been successfully constructed and their structures and properties have been studied.The synergistic effect of solvent molecules,energetic units and auxiliary ligands on the structures and properties of energetic coordination polymers has been explored.The main contents and achievements are summarized as follow:1.The energetic metal-organic framework?MOF?,[Ag₇?tza?₃?Htza?₂?H₂tza??H₂O?]?1?,has been successfully synthesized by hydrothermal method with nitrogen rich ligand 1H-tetrazole-5-acetic acid?H₂tza?and silver salt.Structure analysis shows that there are seven crystallographic independent Ag???ions in an asymmetric unit,and all nitrogen atoms in the ligand H₂tza are involved in the coordination with them to form a compact three-dimensional organic frame structure.A novel anhydrous coordination polymer[Ag7?tza?3?Htza?2?H₂tza?]?2?was obtained by heating dehydration due to the presence of coordinated water molecules in 1.The results show that compared with 1,compound 2 exhibits better explosion performance and almost the same safety performance,thus reflecting the influence of solvent molecules on the energetic characteristics.2.Two coordination polymers,[Ag?Htza?]_n?3?and[Ag?atza?]_n?4?,have been prepared by hydrothermal method with H₂tza and Hatza ligands.Structures analysis shows that they exhibit two-dimensional layer-like structure.Adjacent layers are connected by ?-? interaction to form a three-dimensional supramolecular structure.The characterization results of the energetic properties show that 4 has better explosion heat and thermal stability than that of compound 3,which is mainly due to the modification of the ligands by the energetic elements?amino?,which results in the difference in the structure and properties of the two compounds.3.A novel one-dimensional azido-cobalt???compound,[CO₂?1-mbt?₂?N₃?₄]_n?5?has been solvothermally synthesized by azide and 1-mbt.Structure analysis demonstrates that two crystallographically independent Co???atoms in the asymmetrical unit of compound 5 exhibit rectangular pyramid geometry.The 3D supermolecular network of 5 consists of well-isolated ID metal chains in which the azido bridging ligands assume an unusual pattern of combination with the Co???centre as the sign of[-EE-EO-EO-EO-]n.Energetic characterizations evidence that the resulting compound possesses satisfactory detonation properties,superior lack of sensitivity and thermostability owing to the high nitrogen content?N%=40.10%?and coherent intrachain configuration.The auxiliary ligand?1-mbt?with good mechanical strength and rigid frame is introduced into the existing transition metal azide system,which effectively coordinates the conflict between the high energy and the safety of the material.Alternating current magnetic susceptibility measurements reveal that 5 features a typical behaviour of field-induced slow magnetic relaxation,which is also confirmed by theoretical calculations.We note that 5 as a kind of nitrogen-rich and oxygen-free environment-friendly energy-containing material,has the property of magnetic material.The implementation of this work provides theoretical and practical supports for exploring new bifunctional materials.