Synthesis, Structures And Properties Of Transition Metal Complexes With Pyridyl, Bipyridyl Ligands

The construction of novel metal-organic supramolecular compounds through metal-ligand coordination and intermolecular interactions (hydrogen bonds,π-πstacking, etc.) has become an important rsearch subject in coordination chemistry, supramolecular chemistry and crystal engineering. Because of their novel topological structures and special properties, complexes with terminal pyridyl-substituted ligands have attracted great interest. Anion recognition is an active research field in supramolecular chemistry due to the importance of anions in biology, medicine and environment. A vast number of synthetic receptors have been reported. In recent years metal complexes have also been designed as anion receptors, among which the functionalized bipyridyl ligands are good candidates which incorporate hydrogen bond acceptors as anion-binding sites and the bipyridyl function as metal coordination sites.On the other hand, helical complexes constructed by the bipyridyl ligands have been widely studied. Using chiral substituents on the ligand can induce the formation of only one stereoisomer in the helix.With the aim of constructing novel metal-organic supermolecular architectures that have potential appliations in gas storage, optical, magnetic or anion binding, this dissertation forcuses on the synthesis and crystal structures of transition metal complexes with terminally pyridyl-substitued a-diimine or diiminopyridine ligands and 2,2'-bipyridyl ligands containing carbamate substituents. The luminescent properties or anion binding behavior of the complexes as well as the helical chirality in the metal center with the chiral ligands 2,2'-bipyridyl ligands have been investigated.This dissertation consists of five parts. Chapter 1 is introduction and a brief review of literature work. Chapters 2-5 present the details of the experiments, results and discussion. The main results are as follows:1) A semirigid terminal pyridyl-substitutedα-diimino ligand, N,N'-bis(2,6-diisopropyl-4-(pyridin-3-yl)phenyl)-2,3-butanediimine (L1) was designed and synthesized and a series of metal complexes with novel 1D to 3D structures have been obtained. The influence of cations and anions on building 1D-3D MOFs has been studied.2) A terminal pyridyl-substituted diiminopyridine ligand, 2,6-bis(1-(2,6-diisopropyl-4-(pyridin-3-yl)phenylimino)ethyl)pyridine (L2) was used as building unit to react with transition metal ions, and a series of complexes with novel OD to 2D structures have been prepared. Different conformational modes [(anti, anti, syn), (anti, anti, anti), (syn, syn, anti), (syn, syn, anti)] of the coordinated ligand L2 in the complexes have been obtained. The coordination modes between the ligand and metal and the conformation of the ligand in the complexes are regulated and controlled by the metal center, anions, and reaction solvent systems. The fluorescence properties of some compounds have been performed.3) Three 2,2'-bipyridyl ligands containing carbamate substituents (L3-L5) were used to react with transition metal ions to yield a series of supramolecular architectures (37-49). The anion binding of the carbamate functionality has been studied. Meanwhile, the anion binding ability of the complexes was also investigated in solution by 1H NMR spectroscopy and fluorescence spectroscopy. The results show that the sulfate anion caused a pronounced quenching of the fluorescence of the Ru(Ⅱ) compounds and formed a 1:1 adduct.4) Two chiral 2,2'-bipyridine ligands containing carbamate substituents (L6-L7) and a series of Fe(Ⅱ) complexes with different anions have been prepared and characterized. The induction of the helical chirality in the iron(Ⅱ) complexes with chiral substituents and the influence of the solvent and anion on the chirality of the complexes have been studied by 1H NMR spectroscopy and CD studies.