Design, Synthesis, And Properties Study Of The Metal-Organic Frameworks Based On Polynuclear Copper Units

Metal-organic frameworks（MOFs） is self-assembled coordination polymer of metal ionswith multidentate organic ligands contained oxygen and nitrogen atoms. MOFs have attractedmuch attention owing to their intriguing molecular topologies and potential applications asfunctional materials,such as gas absorption, molecular magnetism, catalysis, ion exchange andnonlinear optics. It is a widely recognized strategy to synthesis of novel structure of the metal-organic frameworks based on new types of secondary building units （SBUs）.In the dissertation,we have intruduced in detail the conditions and methods of synthesis,structural features, thermal stability, photocatalytic and ions exchange properties of MOFsbased on second building units of polynuclear copper clusters. We have successfullysynthesized two new MOFs Cu6（μ₃-O）（μ₃-OH）（pz）6（BTC）（1） andH₂Na₄[Cu₁₂（OH）₆（pz）₆（BTC）6]36H₂O （2）（pz=pyrazolate, BTC=1,3,5-benzenetricarboxylate）. They are both with novel structures adopting solvothermal synthesismethod using multi-carboxylic acid （1,3,5-benzenetricarboxylate） and nitrogen heterocyclicligands （pyzole） and Cu2+ions in a methanolic solution. The hexanuclear copper building unitin1is composed of two triangular Cu3O（H）（pz）3units bridged by carboxyl groups, in whicheach Cu center is coordinatively unsaturated with open coordination sites. Each hexanuclearcopper unit links to three BTC ligands and each BTC ligand connects with three hexanuclearcopper units, thus leading to a three-dimensional （3,3）-connected framework with SrSi2topology. The photocatalytic investigation indicates that compound1exhibits a higherphotocatalytic activity for the degradation of Rhodamine B. Compound2is a12-connectedmetal-organic framework based on an unprecedented cyclic Cu12cluster with large internalcavity bigger than1nm diameter. In1, each CuIIions adopts the square pyramidal geometry,which is coordinated by one nitrogen atom from pyrazolate ligand, one hydroxyl group, andthree carboxyl oxygen atoms from three different BTC ligands. Each BTC ligand is linkedwith two cyclic-type Cu12units and each cyclic-type Cu12unit is connected to12other unitsby BTC linkers, thus featuring a12-connected face-centered cubic net （fcu） with Schl flisymbol （32443656）. As an fcu net,1inherently features octahedral and tetrahedral holes.Ion-exchange investigation shows that1possesses high ion-exchange capacities with somealkali-metal and transition-metal cations.