Synthesis,Structures And Properties Of Metal-Organic Frameworks Based On 3,5-Di(Pyridin-4-Yl) Benzoic Acid And Its Derivatives

Metal-organic frameworks(MOFs),emerging as a new type of porous materials,have currently attracted considerable interest due to their intriguing architectures and structural topologies,high surface areas,tunable pore sizes and designable surface properties,as well as their potential applications in gas sorption,separation and molecular magnetism.In this dissertation,we have constructed 12 new MOFs based on trifunctional ligand 3,5-di(pyridin-4-yl)benzoic acid and its derivatives,and analyzed their topology structures as well as explored their sorption and magnetic properties.These results will be introduced in four parts:1.Two novel MOFs,[Cu(L1)(NO3)]·2DMF·H2O(1)and[Cu(L2)(NO3)]·DMF·2H2O(2)were hydrothermally synthesized using trifunctional ligand HL1 and its skeleton extended derivative(HL2),respectively.The corresponding structure and properties have been studied.MOF 1 exhibits a(3,6)-connected framework with a rare fit-3 topology,while 2 shows a ths-b topology with 4-fold interpenetration.We discussed the relationship between the ligand skeleton and the distinct final networks.Notably,the small pores within framework of 1 have enabled their strong interactions with CH4 molecules.1 was thereby found to exhibit high isosteric heats of CH4 adsorption(23.3 kJ mol-1)and uptake capacity(50.3 cm3 g-1)at 1 bar and 273 K.2.Based on HL1 and its methyl functionalized derivative(HL3),two MOFs,[Co2O(L1)2(DMF)2]·xS(3)and[Co2(L3)3(DMF)](NO3)·xS(4)with the rare reo and sod topology,respectively,were achieved.MOF 3 represents a distinct example of porous MOF with uncommon dimeric clusters as the trigonal prismatic MBB to construct a novel framework consisting of three different nanoscale M12L12 and M24L12 cages.4 is the first example of zeolite-like MOF with 48 nuclear cobalt SOD cages.We also discussed the complexity and potential of the ligand functional related to diverse net topologies.3 exhibits permanent porosity as well as high and selective CO2 uptake.Additionally,the magnetic properties of compounds 3 and 4 are studied.3.A MOF,[Co4(?-Cl)4(L1)4]·6DMF·8H2O(5)with(3,12)-connected sum topology,were hydrothermally synthesized based on a unique S4N4-like[Co4(?-Cl)4]cluster.MOF 5 is the first example of involving chloride-centered tetranuclear SBUs with the smallest size in MOF with such connection.Owing to the bridging chloride decorated 2D intersecting channels with small pore opening,5 exhibits high CO2 uptake(20.0 wt%at 1 bar)with high CO2 over N2(27.5)selectivity at 273 K.4.Seven other(3,6)-connected frameworks,6-12,were hydrothermally synthesized with HL1,HL3 and HL4,which exhibit diverse topological structure.MOFs 6 and 7 show an rtl topology,while 8 and 9 exhibit a rare ant topology.Notablely,10,11 and 12 have a rare chiral anh topology.Detailed structure analysis revealed that although the modification of HL1 ligand with methyl or methoxyl group did not change the coordination sites,it assuredly changed the geometric configuration and symmetry of parent ligand,and eventually made profound impact on the network structure.In this dissertation,we have constructed a series of MOFs with diverse topologies,and studied their potential application in gas sorption and magnetism.The complexity and potential of the ligand functional related to the building blocks and diverse net topologies have been outlined.We believe that these results would facilitate the exploration of new MOFs with charming molecular topologies and properties,and afford theoretical and experimental basis for directing the synthesis of novel frameworks.