Study On The Synthesis And Performance Of Cu And Zr-metal Organic Framework Compounds Based On Carboxylic Acid Ligands

Metal-organic frameworks(MOFs)have attracted widely attentions for their potential applications in gas storage and separation,catalysis,sensing,fluorescence,supercapacitors and other areas.Hydrogen spillover is a typical storage method for MOFs,which greatly improves their hydrogen storage capacity at room temperature.So far,more than half studies uses IRMOF-1 and IRMOF-8.However,both of them are unstable in air and unsuitable for practical applications.Zr-MOFs have high water and chemical stability and have not yet been applied in this field Therefore,in chapter two,we explored the hydrogen spillover properties of UiO-66(Zr-bdc)and UiO-67(Zr-bpdc)for the first time.In comparision to other MOFs,we found that the charges on the metal ions of MOFs have an effect on hydrogen storage properties at room temperature when other condition is certain.And the theoretical calculations confirmed that,when connected to the same carboxyl-ligand,the metal ions with lower valence have stronger tendency to combine H,suggesting the corresponding MOFs would absorb more hydrogen by the spillover mehod.Considering the stability of MOFs,we therefore deny the hydrogen spillover of the carboxylate MOFs,which needs us to seek better materials,for the real application of hydrogen storage at room temperature.The high stability of Zr-MOFs is mainly due to the high valent state and oxophilic of Zr4+,which resulting in strong Zr-O bond.Due to this reason,the crystals usually grow too fast to obtain single crystals suitable for structure determination.In chapter three,we synthesized a novel Zr-MOF((Zr6(?3-0)4(?3-OH)4(TCPS)2(H2O)4(OH)4,1)based on a tetrahedral ligand(tetrakis(4-carboxyphenyl)silane,TCPS).Compared to other Zr-MOFs,compound 1 is a good material for CO2/CH4 storage,and is a wide bandgap semiconductor.We also summarized the hydrothermal stability of other Zr-MOFs,calculated the NBO(nature bond orbital)charges of the coordinating oxygen atoms of the corresponding carboxylate ligands and analyzed the effecting factors.Besides the known reasons of hydrothermal stabilities of Zr-MOFs,we demonstrated that NBO charges of coordinating atoms of the ligands can be used to explain the hydrothermal stability of Zr-MOFs,which has important significance for the design and synthesize novel stable Zr-MOFs.Many photosensitive MOFs based on bipyridinium(viologen)ligands have been reported,but their hydrothermal stability rarely reported.However,the hydrothermal stability is a bottleneck problem for their practical application.And almost all those ligands are flexible bidentate acids.In chapter four,we design and synthesized a new rigid bipyridinium ligand(1,1'-bis(3,5-carboxyphenyl)4,4'-bipyridine,L2),and synthesized a new coordination polymer([Cu(HL2)(Cl)]·2H2O,2),and studied the hydrothermal stability,photosensitivity,fluorescence and semiconductor properties of 2.We find that 2 is a fluorescent material with good stability and a narrow bandgap semiconductor.We analyzed the reasons for 2 performed optically inert,which will have good reference for design and synthesize special MOFs which based on L2 or other viologen ligands.