DIPYRIDYL AMIDE-FUNCTIONALIZED POLYMERS PREPARED BY RING-OPENING-METATHESIS POLYMERIZATION (ROMP) FOR THE SELECTIVE EXTRACTION OF MERCURY AND PALLADIUM

Ring-opening-metathesis polymerization (ROMP) was used for the prepara tion of a dipyridylcarbamide-functionalized polymer suitable for solid -phase extraction of metal ions from aqueous solutions. Resins were pr epared by the copolymerization of the functional monomer N,N-di-2-pyri dyl-endo-norborn-2-ene-5-carboxamide (I) with 8a-hexahydro-1,4,5,8-exo -endo-dimethanonaphthalene (II), using the well-defined Schrock cataly st Mo(N-2,6-i-Pr2C6H3)CHCMe2Ph(OCMe(CF3)(2))(2) (III). The polymerizat ion proceeds in a living manner, allowing the stoichiometric buildup o f polymers. NMR investigations proved the expected backbone structure of the resulting polymers, where the binding site of the monomer remai ns unaffected in course of the polymerization. The new materials were investigated in terms of their complexation behavior versus a large va riety of mono-, di-, tri-, and tetravalent metal ions employing UV-vis spectroscopy as well as AAS and ICP-OES techniques. The polymer-bound dipyridylamide ligand showed excellent selectivity toward Hg2+ and Pd 2+, allowing the selective extraction of both divalent metal ions over a broad range of concentrations from complex mixtures. Due to the sta bility of the resulting complexes, high loadings of the material with both metals were achieved.:To elucidate the chemistry of complexation, X-ray structures of compound (I) as well as ESI-MS investigations of the complex of I with Pd2+ were performed. I crystallized in the monoc linic space group P2(1)/c, and forms 1:1 complexes with Pd2+ under con ditions identical to the SPE experiments.