The Synthesis And Properties Study Of MOFs Based On N-heterocyclic Carboxylic Ligands

Inorganic-organic hybrid materials have been intensively investigated because of not only fascinating structural diversities for supramolecular chemistry and crystal engineering,but also distinctive properties inherited from the interaction of inorganic and organic components.It has been observed that organic ligands play crucial roles for the designed synthesis of some interesting coordination networks,such as the donating type,the flexibility,and the geometry of the organic ligands.Therefore,N-heterocyclic carboxylic acid ligands 4-((3-(pyrazin-2-yl)-1H-pyrazol-1-yl)methyl)benzoic acid(Hpypymba),4-((3-(pyridin-2-yl)?1H-pyrazol-1-yl)methyl)benzoic acid(Hpyznpy),2-(3-pyridin-2-yl)-1H-pyrazoI-1-yl)acetic acid(Hpypyaa),with both rigidity and flexibility were selected.These three ligands are rich in N-,O-donors,slightly different in the coordination site and the volume of the ligand,so it is convenient to study the structure diversity of the complexes synthesized by these ligands.Different types of transition metal ions(Zn(II),Co(?),Cd(?))react with the ligand to synthesize novel metal organic coordination polymers.The structures of the complexes were analyzed by X-ray diffraction.The coordination polymers were characterized by elemental analysis,thermogravimetric analysis and fluorescence analysis.Finally,the properties of the complexes were studied.Seven new compounds,[Zn(pypymba)2]n(1),[Co(pypymba)2]n(2),[Cd(pypymba)2]n(3),[Cd(Hpypymba)Cl2]n(4).{[Cd(pypymba)Cl]·C2H5OH·H20}n(5).[Cd(pypyaa)Cl]n(6),?[Cd2(pyznpy)2Cl2H2O]·H2O}n(7).were hydrothermally synthesized by tuning the metal ion's species,counter anion,solvents and pH values.X-ray diffraction analysis results show that:the main structures of the compounds 1,2m and 3 are extended to similar 3D structures by C-H...N,C-H…O hydrogen bonds and ?...? stacking under the same synthesis method.Changing the counter anions and pH value,bidentate chlorine bridged 1D compound 4 was obtained by;compounds 5,6 with monodentate chlorine bridging structures can be obtained by varying the solvent,pH and ligand's volume.Reducing the N-coordination site,then the complex has no chlorine bridged compound 7 was obtained.The analysis of this series of coordination polymers shows that the types of antagonists,the coordination sites of ligands,the coordination numbers of ligands,the volume of ligands,and the solvent,pH,etc.are of great importance to form structurally diverse coordination polymer.In addition,the antioxidation activity of complex 1 and complex 2 and the fluorescence of quencher quenching complex 7 were studied in this paper.The results showed that:(1)The complexes 1 and 2 had the potential of substitution of SOD,and the inhibitory concentration(IC50)was 19.1?g/mL and 36.5?g/mL respectively.(2)The luminescent properties of compound 7 and the ones immersed in various kinds of organic compounds and nitrate@EtOH solutions have been investigated.Importantly,7 shows highly sensitive response to nitrobenzene[10-3mol(NB)/L]and Fe3+[9 × 10-7mol(Fe3+)/L]through luminescence quenching effects,making it a promising luminescent sensor for nitrobenzene and Fe3+ Through the above research,we provide preliminary theoretical guidance and experimental basis for the development of new medical materials with simulated biological activity and fluorescent probe materials.