Synthesis And Performance Research Of Metal Organic Framework Based On The Rigid Carboxylic Acid And Flexible Imidazoles Pyrazine Heterocyclic Ligands

Metal-organic frameworks?MOFs?,as a new generation of highly porous molecular crystalline materials assembled by coordination bonds between metal ions and organic ligands,have attracted immense attention during the last two decades due to their fantastic structures and various potential applications,such as strategic storage and separation of gases,catalysis,magnetism,luminescence and chemical sensing and so on.In this paper,MOFs using new nitrogen heterocyclic organic ligand were synthesized by hydrothermal synthesis,and the structure and performance were characterizated and testing.Concrete contents can be divided into the following several parts:In the first part of this paper,the development background,synthetic method,influencing factors and performance testing of MOFs are introduced.In the second part of this paper,a newly designed rigid ligand,ie2,3,5,6-tetra?4-carboxyl phenyl?pyrazine,was synthesized and then reacted with different metal salts under the hydrothermal condition to construct six porous MOFs:{Cd?L1?×2H₂O}n?1?,{Pb₂?L1?}n?2?,{La?L1?×H₂O×2.7 H₂O}n?3?,{Sr₃?L1?2×6H₂O×2.6H₂O}n?4?,{Ce?L1?× 4H₂ O × H₂O}n?5?and {Mn₂?L1?}n?6?,which were further characterized.In addition,thermogravimetric,solid-state ultraviolet,solid-state fluorescence,gas adsorption and hydrogen evolution reaction have been also investigated.Complexes showed good thermal stability,decomposition temperature can reach 450 °C.Relative to L1 ligand,complexes 1 and 4 showed obvious fluorescence enhanced performance,and could be used as potential fluorescent material.Gas adsorption experiment found that complexes 3 and 6 showed very good N2 adsorption performance,and the complexes did H₂ adsorption test of 6.Complexes 2 and 5 show a certain performance of electrochemical activity of hydrogen evolution.In the third part of this paper,a new four tooth imidazole ligand was synthesized and then were assembled with different carboxylic acids and metal salts to form four new MOFs: {Co?L2?A}n?L2=2,3,5,6-tetra?4-methylene-1-imidazole phenyl?pyrazine A= 5-nitroisophthalic acid??7?{Co?L2?×2H₂O }n?8?{Co?L2?B }n?B= Diphenyl ether dicarboxylic acid??9?{Mn₂?L2?C₂ }n?C=naphthalene-1,4-dicarboxylic acid??10?.The structure was confirmed by single crystal X-ray diffraction and characterized by the P-XRD,IR.The properties of some compounds were tested and the properties of hydrogen evolution reaction were revealed favourable of complex 8.The last part;Conclusion.