Ligands Based On Pyridine And Carboxylic Acids, Supramolecular Complexes

On the focus of current hot research topic of coordination polymer and supramolecular chemistry, multifunctional organic spacers such as bipyridine derivant, polycarboxylate and pyridyl-carboxylate are applied to react with diverse metals, affording a series of novel supramolecular coordination complexes. And on the basis of their structural characterization and performance study, the potential relationship between structures and properties are primarily discussed.In chapterâ… , the recent research progresses of coordination polymers, network topology and porous coordination polymers are represented. Then the research significance and main outcomes of this thesis are summarized.In chapterâ…¡, four diffrent supramolecular coordination complexes have been synthesized with 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4-bpt), 1,4-nda and Co^â…¡, Zn^â…¡ and Cd^â…¡ ions, which display diverse network structures such as 2-D→3-D polycatenated framework, host-guest supramolecular lattice with different coordination chains, 2-D parallel interpenetrated (4,4) layer. Their structural discrepancy can be significantly modulated by the metal centers and even the pH value of reactive solution. On the other hand, Pb^â…¡ coordination polymers with 1,4-nda and 2,6-nda exhibit the distinct 3-D 5-connected network and 3-fold interpenetrated diamond framework, revealing the isomeric effect of such tectons.In chapterâ…¢, a series of novel Cd^â…¡ coordination complexes with chelate reagent 2-bpt (the isomer of 4-bpt) and multiform inorganic or organic anions have been prepared. Structural analysis reveals that the assemblies of these complexes are mainly directed by counter anions, followed with the change of anions from simple inorganic species (SCN^-/dca/Cl^-) to organic ones (ip/nip/tp/chdc), diversiform structures are formed varying from mononuclear, tetranuclear molecules to infinite 1-D and 2-D frameworks.In chapterâ…£, six new supramolecular coordination complexes constructed from the 4,4'-(hexafluoroisopropylidene)bis(benzoic acid) tecton (H₂L) and familiar metal ions under different conditions, which display multifarious coordination arrays such as the 1-D zigzag chains, a 2-fold interpenetrating layered network embodying 2₁ helical motifs, and a 3-D rod-based pcu framework featuring 4₂ helicity. Structrual analysis reveals that the versatile binding modes of H₂L with the metal ions result in these diverse structural motifs, and which also may be directed and regulated by the choice of metal ions and/or synthetic conditions. The results demonstrate that this flexible tecton can be rationally used to construct novel metal-organic frameworks especially helical materials.In chapterâ…¤, reactions of different metal salts with 4-(3-pyridyl)benzoic acid (3,4-Hpybz) under general condition result in four novel 3-D metal-organic frameworks with new (3,6)-connected net topology. In the Mn^â…¡, Zn^â…¡, or Cd^â…¡ complexes, the octahedral metal centers are extended by the 3-connected pybz tectons to constitute a 3-D array with the Schl(?)fli symbol of (3.4.5)(3².4⁴.5⁵.6².7²), whereas Pb^â…¡ complexe displays a different 3-D (4².6)₂(4⁴.6².8⁹) framework, which represents a subnet of (4,8)-connected fluorite lattice. This work suggests that the anionic module 3,4-pybz may potentially serve as a versatile connector for the construction of mixed-connected coordination frameworks.