Synthesis,Separation And Catalysis Properties Of Coordination Polymers Based On Aromatic N-oxide Ligands

The chemistry of organic-inorganic coordination polymers and supramolecular assemblies has become one of the most active and frontier research fields in the world. In recent years, organic- inorganic coordination compounds as a new type of functional supramolecular materials have been received intense attention owing to their potential applications as gas adsorption and purification, catalytic materials, drug delivery, and so on. In this thesis, a series of organic ligands with pyridine or pyrazine N-oxide groups were synthesized. The coordination chemistry based on these new ligands and metal ions was investigated. Totally 38 new coordination compounds were prepared and fully characterized by IR, elemental analysis, X-ray single-crystal diffraction and powdered X-ray diffraction. The luminescent properties, molecular adsorption and separation, the highly efficent heterogeneous catalysts for Knoevenagel condensation were investigated.I. A novel Ag(?)-MOF has been generated from a new Schiff-base bridging N, N’-dioxides ligand 3, 6-bis[2-(4-oxide-quinoxaline)-yl]-4, 5-diaza-3, 5-octadiene and Ag Sb F6. The host–guest chemistry of this Ag(?)-MOF was investigated and it is able to reversibly absorb and separate benzene from its six-membered ring organic analogues, such as cyclohexane, cyclohexene, o-, m- and p-xylene, in both liquid and vapor phases. In addition, the guest-dependent luminescent properties of the Ag(?)-MOF were investigated primarily.II. Two new rigid ligands, namely 3, 5-bis(4-pyridyl)-pyridine N-oxide and 2, 6-bis(3-pyridyl)-pyridine N-oxide were prepared by Suzuki–Miyaura crosscoupling reactions between bromine-substituted pyridine N-oxide and the corresponding pyridine boronic acids in good yields. These ligands have the following features: 1) both contain pyridyl and N-oxide donors with different coordinating natures; and 2) they are generally expected to link relatively soft metal ions, such as zinc(II) and cadmium(II), to CPs with a free N-oxide moiety, as potential Lewis base type catalysts for specific organic reactions. Furthermore, four CPs based on these ligands have been synthesize. They all display a 1D chain motif with an open pyridine N-oxide site. Notably, these compounds with free pyridine N-oxide moieties, are the first highly active heterogeneous CP catalysts for Knoevenagel condensation.III. Five new rigid ligands bridging by pyridyl-N-oxide groups were prepared and 14 coordination polymers generated from the new rigid ligands were synthesized. The structures of these compounds were investigated.IV. Eight new rigid ligands with pyridyl-N-oxides as terminal coordination groups were prepared and 14 coordination compounds with novel structures generated from the new ligands were synthesized.