Photocatalytic Hydrogen Production And Gas Adsorption And Separation Of MOFs Based On Host-guest Chemistry

The metal-organic frameworks（MOFs）is a kind of porous crystalline material formed by self-assembly of organic ligands and metal ions or ion clusters through coordination bonds.It has a wide range of studies on molecular adsorption separation,gas adsorption,fluorescence,magnetism,catalysis and so on.In this paper,we use Zn（Ⅱ）-MOF to adsorb Fe₂S₂（CO）₆ and photosensitizer（Ru（bpy）₃Cl₂）in order to prepare a composite MOF,and the composite MOF can be used for the decomposition of water in visible light;Cd（Ⅱ）-MOF with square channels can adsorb and separate C₂H₂ and C₂H₄;the fluorine-bridged organic nitrogen-containing ligands and the five-membered heterocyclic hydrazone-bridged organic ligands were synthesized and studied their self-assembly reaction chemistry.Ⅰ.A porous Zn（Ⅱ）-MOF with open hexagon channels was used to adsorb Fe₂S₂（CO）₆ and photosensitizer（Ru（bpy）₃Cl₂）in order to prepare a composite MOF,the composite MOF can be used for the decomposition of water in visible light.Ⅱ.A porous 3D Cd（Ⅱ）-MOF with open square channels was used to adsorb and seperate C₂H₂ and C₂H₄.We characterized by X-ray single crystal diffraction to identify the specific binding sites of acetylene in Cd（Ⅱ）-MOF.A C₂H₂ molecule was bonded to a perchlorate ion in the square channel through four sets of strong C-H···O hydrogen bonds.We also compared [Cd（L）₂（BF₄）₂]·H₂O and[Cd（L）₂（ClO₄）₂]·H₂O for the separating performance of C₂H₂ and C₂H₄.The Cd（Ⅱ）-MOF-ClO₄ is much better than the Cd（Ⅱ）-MOF-BF4.Different ions in the channel lead to different hydrogen bonds of acetylene and hydrogen bonds.Ⅲ.Eight fluorine-bridged ligands including pyridine and carboxylate groups were synthesized.The self-assembly of the ligands and transition metal ions Ni（Ⅱ）,Cu（Ⅱ）,Co（Ⅱ）,Cd（Ⅱ）and Zn（Ⅱ）has been investigated.Eight new compounds were synthesized based on these ligands.The adsorption properties of compound6 for carbon dioxide were studied.Ⅳ.Twenty hydrazone-bridged ligands including five-membered heterocyclic were synthesized.The self-assembly of the ligands and transition metal ions Cd（Ⅱ）and Zn（Ⅱ）has been investigated.Six new compounds were synthesized based on these ligands.The adsorption properties of compound 10 for carbon dioxide were studied.The study prove that: the adsorption and separation of MOFs are very important.Fluorene or acylhydrazones briding ligands possess novel structure and outstanding functional properties.