Design,Synthesis And Photoelectric Properties Of Polycarboxylic Acid MOFs Based On Polynuclear Clusters

Metal-organic framework materials(MOFs)have tunable metal clusters and organic ligands,so they have excellent properties such as designable topology and adjustable channel structure.Therefore,they have a wide range of applications in the fields of magnetism,fluorescence sensing,gas storage and separation,catalysis and energy storage.However,their poor stability limits their widespread use.Design and synthesize metal-organic framework materials with high water stability,and its development has potential application value in fluorescence sensing and capacitive devices.This thesis adopts the method of crystal engineering to design the metal cluster structural unit,aiming at synthesizing stable MOFs with high nuclear clusters and high connections.Moreover exploit its applications in the detection of environmental pollutants with fluorescence sensing and new energy capacitor devices.Firstly,design and synthesize metal-organic framework materials containing lanthanide metals La,transition metals d¹⁰(Zn²⁺,Mn²⁺,Co²⁺,etc.).Even metal clusters such as dissimilar metals d-f,d-p,and develop their applications in fluorescence sensor detection environmental pollutants.Secondly,a high-nuclear transition metal organic framework material was synthesized,and its application in capacitors was developed for metal cluster units with redox activity.Finally,aiming at the synthesized MOFs with high specific capacitance and good stability,metal oxide nanomaterials were prepared and their capacitance performance was improved.The research work of this paper is as follows:(1)Based on the selection of H₃TATB(4,4',4''-s-triazine-2,4,6-triyltribenzoic acid)and H₄PDTA(5,5'-(propane-1,3-diylbis(oxy))diisophthalic acid).The?-?conjugated H₃TATB and lanthanide metal Tb were used to synthesize a dual-core Tb cluster[Tb₂(COO)₆],metal-organic framework material 1 features a(3,6)-connected 2D network structure.A flexible multifunctional p-?conjugated ligand H₄PDTA was selected to synthesize a rare metal-organic framework material 2 with a trinuclear[Zn₂Ca(COO)₆]cluster group,which has a(4,8)-connected three-dimensional network structure.The application of 2 in the detection of Fe³⁺,Cr₂O₇^2-,Mn O₄^2-,NH₃·H₂O,and N₂H₄·H₂O etc.was specifically studied.Its fluorescence quenching constant K_SVis 4356.7,1152.2,1106.3,327.5,and 556.0 M^-1in turn;it also has relatively high sensitivity,and its corresponding detection limits LOD are 0.01880,0.02914,0.02402,0.1402,and 0.07533 m M,respectively.(2)By using multifunctional carboxylic acid ligands[HPBPA(1,3-bis(4-ethoxypyridine)benzoic acid),H₃BTB(1,3,5-tris(4-carboxyphenyl)benzene)and H₃TATB]and transition metals(Co,Mn etc.)were selected to self-assemble into three MOFs under solvothermal condition.Complex 3 has a 3D framework structure based on pentanuclear cobalt clusters[Co₅(CO₂)₄(N)₈(C₂H₃O₂)₂];Complex 4 has a three-dimensional nested cage structure.The 3D networks structure feature is based on 12-core Mn cluster{[Mn₃O3(COO)₆]₄},denoted as the octahedral cage encapsulates a tetrahedral cage(complex 5).In addition,the three electrodes at current density is 1 A g^-1in 1M KOH electrolyte,the specific capacitance are 424.4 F g^-1,266.7 F g^-1,and 558.0 F g^-1,respectively.After 1500 charge and discharge cycles,the capacitance retention rates were 47.1%,66.7%,and 40%,respectively.(3)Based on the hexanuclear Co-Cluster-Based complex 4 as precursor,the sample Co₃O₄-6 obtained by carbonizing at high temperature.Its specific capacitance is 327.1 F g^-1.After 1500 charge and discharge cycles,its capacitance retention rate reached 61.5%.The design of this experiment improves the cycle stability of this porous Co₃O₄-6.