Investigation Of The Syntheses And Properties Of Polymolybdates Functionalized By Nitrogen-Heterocycle Or Carboxylic Ligands

In this thesis, N-heterocycle or carboxylic ligands were used to react with in-situ generated polymolybdate anion to construct functionalized polymolybdate derivative with certain functions. The influence of the reaction conditions for the final products was investigated such as pH, counterion, solvent, and charge density of coordination atom. By way of molecular design, N-heterocycle or carboxylic ligands were realized to coordinate to the polymolybdate anions by different covalent bonds. The structures of these new functionalized polymolybdate compounds also vary from 0D to 3D.Under conventional conditions, we select pyridine derivative, imidazole, multi-carboxylic acids, carbon dioxide, and carboxyl containing copper complex as organic ligands to react with polymolybdate inorganic component and new sixteen polymolybdate compounds were successful synthesized. These new complexes were characterized by elemental analysis, IR and XPS spectra, TGA, electrochemical and XRD single crystal analysis.1. In aqueous phase, four polymolybdate derivatives were synthesized by using nicotinic amide or nicotinic acid as organic ligands:Compounds 1?3 realized the functionalization of nicotinamide withγ?type octamolybdate. Due to the different arrangement of Na+ ions, compounds 2 and 3 display 1D chain and 2D layered structures, respectively. While compound 4 only shows H-bond linked supramolecular framework, because the N atom in nicotinic acid does not coordinate to the polyanion.2. In aqueous or mixed phase, imidazole and transition metal ion react with molybdate forming four imidazole-containing polymolybdate derivatives:Compound 5 contains the imidazole functionlizedγ?type octamolybdate polyanion. These polyanions together with K+ and copper complex cations to form 3D framework with 1D channel. Under the same conditions, compounds 6 and 7 present different structures: compound 6 is the first example of Keggin-type heteropolymolybdate with Co2+ ion as central heteroatom; while compound 7 only contains a heptmolybdate anion coordinated by a [Co(H2O)5]2+ cation. In mixed solvent, compound 8 represent a 1D chain structure that the heptmolybdate anions are linked by [Co(imi)2(H2O)2]2+ cations.3. In aqueous phase, the carboxylic ligands were used to react with molybdate and four carboxyl functionalized polymolybdate formed:Compounds 9 and 10 realize the functionalization of carboxyl withγ?type octamolybdate polyanion. Compounds 11 and 12 realize the functionalization of carboxyl with decamolybdate polyanion, where the multi-carboxylic acids coordinate to the decamolybdate anions by three covalent bonds and present interesting meso-helical chain structures. In addition, the film containing 11and polyvinyl shows photochromic properties.4. In aqueous phase, two heteropolymolybdate were functionalized by carbon dioxide ligands:In compounds 13 and 14, CO2 ligand coordinates to the [PMo11CoO39(H2O)]5- or [SiMo11CoO39(H2O)]6- anions by its oxygen atoms, showing 1D chain-like structures. It is the first time to realize the coordination of CO2 by polyoxoanions.5. In water/DMF mixed solvent, the as-synthesized copper complex was used as ligand to react with polymolybdate and chain-like or layered octamolybdate compounds were isolated:Using two-step synthetic method, compound 15 confirm that the terminal oxygen atom can substitute the weak ligand in the copper complex. It was also found that the magnetic properties can be modulated by the conformation change of the as-synthesized copper complex (CuL1). Compound 16 further realized the coordination of carboxyl and copper ion with polymolybdate anions simultaneously and present 2D layered structure. Magnetism of compound 16 also indicates that the substituted polyanion can affect the magnetic properties of as-synthesized copper complex (CuL2).