Synthesis,Structure And Properties Of Metal-Organic Frameworks Based On Tetrazole Ligands

Metal-organic frameworks(MOFs),as a new type of porous material,are widely used in various fields such as optics,electricity,gas storage and separation,molecular magnetism,chemical catalysis,chemical sensing,and biomedicine.In this thesis,a series of MOFs were synthesized by solvothermal method,and their crystal structure,optical properties,thermal stability and nitro compound sensing were studied.The contents are as follows:(1)First of all,three organic ligands containing tetrazole groups were synthesized.The organic ligands containing tetrazole groups were N-ethyl-2,7-ditetrazolecarbazole(L1),and tetra-(4-tetrazole-benzene)ethylene(L2)and 2,2'-ditetrazole biphenyl(L3).Secondly,L1 is used to coordinate with two transition metal ions Zn(II)and Mn(II)and obtains complexes 1 and 2 under solvothermal conditions.Complex 1 belongs to the orthorhombic system with a 3D structure,Zn(?)shows a regular tetrahedral coordination geometry.Complex 1 has relatively high fluorescence quenching behavior for 4-NF.When 45?L of 4-NF is added,the fluorescence quenching efficiency reaches to 96.4%,and the detection limit is 5.248×10^-7 M.Compared with other nitro compounds,complex 2 exhibits high fluorescence quenching behavior for TNP.When 50?L of TNP is added,the fluorescence quenching efficiency of complex 2 reaches to 94.1%,and the detection limit is1.457×10^-6M.(2)Ligand L3 is coordinated with transition metal ions Cd(?)and Ni(?)under solvothermal,and two novel complexes 3 and 4 are obtained.Complex 3 crystallizes in the monoclinic space group P 2₁/n with a layered-like 2D structure.Complex 3 possesses fluorescence quenching effect for TNP.When 55?L of TNP is added,the fluorescence quenching efficiency reaches to 91.8%,and the detection limit is 5.576×10^-5M.Complex 4 crystallizes in the monoclinic space group C2/c with a layered-like 2D structure.In anion fluorescence sensing test,adding SO₄^2-,SO₃^2-,HSO₄^-,Cl^-can enhance the fluorescence intensity of complex 4,while NO₃^-and NO₂^-can quench the fluorescence.In a word,in this thesis,three organic ligands bearing tetrazole groups are designed and synthesized,and four metal-organic complexes are obtained after coordination with transition metal ions,and their applications in nitro compound sensing and anion/cation fluorescence detection are studied.