Syntheses, Structures And Properties Of Novel Coordination Polymers Generated From Di(Pyridyl)imidazole Derivatives

Metal-organic coordination polymers(MOCPs) as a newly-identified functional molecule-based materials,have attracted much more attentions because of their flexible tailoring,various topologies and promising applications in hydrogen storage,ion-exchange, adsorption,molecular recognization,catalysts along with optics,electrics,magnetism and enantioselective separation.According to the principle of molecular engineering,it is possible that rational design and synthesis of novel multifunctional materials by selecting certain geometric metal ions and special organic ligands.At the same time,MOCPs can be endowed with multifunctional properties by selecting functional metal ions and organic ligands with functional groups.The aim of this thesis is the synthesis of new coordination compounds on the basis of比di(pyridyl)imidazole derivatives ligands and metal zinc or cadmium ions.The study on synthetic conditions and rules for these new compounds,topological analyses,and the exploration of relationships between structures and properties for these new compounds are also carried out.These compounds have been structurally characterized by elemental analyses, IR,XRPD,TG and single crystal X-ray diffractions.In addition,the thermal stabilities, fluorescent activity and photovoltage transients of these compounds have been studied.These results will be introduced from the following four issues:1.Five novel coordination polymers,[Cd(bpib)₍0.5_L¹](1),[Cd(bpib)_0.5(L²)]·H₂O(2), [Cd(bpib)_0.5(L³)](3),[Cd(bib)_0.5(L¹)](4),and[Zn₂(bpib)(oba)₂]·8H₂O(5),have been hydrothermally prepared on the basis of different polygons or polyhedra.Compounds 1-3 displayα-Po topological nets with different degrees of interpenetration based on the similar octahedral[Cd₂(CO₂)₄]building blocks.Compound 4 is a six-fold interpenetrating diamondoid net based on tetrahedral MBBs.Compound 5 is a eight-fold interpenetrating three-connected net with(10,3)-b topology based on trigonal MBBs.By careful inspection of these structures,we find that various carboxylic ligands and N-donor ligands with different coordination modes and conformations,and metal centers with different geometries are important for the formation of the different MBBs.2.Four novel coordination polymers,[Zn(L¹)(oba)](6),[Cd(L²)_0.5(oba)]·H₂O(7), [Cd(L³)_0.5(oba)]·(L³)_0.5(8),[Cd(L⁴)(oba)]·H₂O(9) have been synthesized under hydrothermal conditions.In compound 6,oba^2-,L¹ ligand and Zn^â…¡or Cd^â…¡ions assemble to form the parallel chains which are linked by the weak hydrogen bonding andπ…πstacking interactions to give the 2D supramolecular sheet.In 7,L² ligands link[Cd(oba)]double-chains to give a 2D sheet which is assembled byπ…πstacking interactions to obtain a 3D supramolecular net.In 8,the double-chains constructed by Cd^â…¡and oba^2- anions are linked by one kind of L³ ligand to a layer-like structure which is assembled byπ…πstacking interactions to show a 3D supramolecular structure.In 9,oba^2- anions coordinate to Cd^â…¡cations to form chains which are connected by L⁴ to form a four-folded interpenetrating diamond network.