Hybrid Materials Based on a Terpyridine Carboxylate Ligand: A Method for Introducing Light Harvesting and Auxiliary Metal Centers into Metal-Organic Frameworks

Metal-organic frameworks (MOFs) are attractive canditates for hydrogen storage and photovoltaic applications owing to their extremely high surface area (often exceeding 1,000 m2/g), and tunable chemical functionality.[1-3] Although the hydrogen storage capacity of MOFs has been extensively explored, the design of MOFs for photovoltaic applications is still in its infancy. In this work, a method for introducing light-harvesting and auxiliary metal centers (for hydrogen storage) into metal-organic frameworks is proposed. Toward this goal, nine metal-organic materials based on 4'-(4-carboxyphenyl)-2,2':6',2"-terpyridine[4] (HL) were synthesized and structurally characterized by single crystal X-ray diffraction. Two of these materials which exhibit channels greater than one nanometer in diameter were fully characterized by TGA, EA, and PXRD. Additionally, a number of discrete [M(L)2] complexes were synthesized and the photoactive ruthenium complex, [Ru(HL)2][PF6]2, was reacted with metal salts under solvothermal conditions. Evidence is presented which indicates the air-sensitive crystals produced by reaction of this complex with zinc(II) ions in N,N-dimethylformamide have the same topology as the large-pore metal-organic framework, MOF-5.[5] Further studies to reveal the potential of this type of material in photocells are proposed