Rare-earth, Transition Metal Coordination Polymers Constructed By BTB And Thiophenedicarboxylic Acid Ligands

Coordination polymers are assembled with organic ligands and metal clusters by coordination bond or hydrogen bonding between metal ions,π-π stacking or other weak interactions. Due to their high surface area, large pore sizes, high stability, low density and flexible tailoring, porous metal-organic framework materials have promising applications in separation of the gas storage, catalysts, magnetic property, optical material and drug delivery. They have received rather considerable attention in the fields like inorganic chemistry, crystal engineering and biochemistry.There is still a great challenge on the choice of appropriate organic ligand and metal ion on the assembly of the expected framework structure. A large number of studies have shown that the symmetrical heterocyclic carboxylic acid ligands are easier to form diverse framework. For this reason, we selected one tripodal organic ligand and two linear carboxylate ligands:bezene-1,3,5-tribenzoic acid (H3BTB), dithieno-[1,2-b;4,5-b’]-benzene-2,6-dicarboxylic acid. In this paper, four metal-organic frameworks have been synthesized by solvothermal synthetic techniques based on transition and lanthanide metal ions. These coordination polymers were characterized by X-ray single-crystal diffraction, infrared spectra, elemental analysis, XRD, thermogravimetric analysis, and we discussed their structural characteristics and properties. This paper includes the following four chapters:In the first chapter, we briefly introduced the basic conception of coordination polymer, the classification of the coordination polymer, and the recent research results in the field as well as the significance and the progress made in this paper.In the second chapter, two kinds of MOFs based on bezene-1,3,5-tribenzoic acid and nickel nitrate, neodymium nitrate were synthesized by hydrothermal method:(H3O)2[Ni6(BTB)2(H2BTB)(HBTB)3(μ3-OH)2(μ2-OH)2(H2O)3]·22H2O (1) and [Nd2(BTB)2(H2O)2]·3H2O (2). Compound1is a twelve-connected3D framework with (32.4)2(38.422.524·610.72) topology, there are two hexanuclear clusters which can be described as [Ni6(μ3-OH)(μ2-OH)2(O2C-)14(H2O)](SBU1) and [Ni6(μ3-OH)2(μ2-OH)2(O2C-)12(H2O)2](SBU2). We discussed the magnetic behavior of1. In Compound2, there are two independent Nd ions, and they formed two kind infinite Nd-carboxylate chains:Ndl-carboxylate chain and Nd2-carboxylate chain, the two kind infinite Nd-carboxylate chains connected with BTB ligand to construct a3-D framework.In the third chapter, two Er(Ⅲ)-based porous metal-organic frameworks were synthesized and discussed,[Er2(L1)3(H2O)2]·4H2O (3) and [Er3(L2)4(CH3O)(H2O)6]·20H2O (4)(L1=dithieno[1,2-b;4,5-b’]benzene-2,6-dicarboxylic acid, L2=dithieno[1,2-b;5,4-b’] benzene-2,6-dicarboxylic acid. Single-crystal X-ray analysis reveals that3crystallized in the C2/c space group,4crystallized in the Cmcm space group.In the conclusion, we have summarized the structures and properties of the four coordination polymers. The research provided a new route for design and synthesis of polynuclear metal cluster polymers with carboxylate ligands.