Crystal structure of a porous zirconium phosphate/phosphonate compound and photocatalytic hydrogen production from related materials

The preparation, structure, and catalytic properties of porous zirconium phosphate/phosphonate compounds are discussed. The crystal structure for the Zr-2(PO4)(O3PCH2CH2(viologen)CH2CH2PO3)X(3) . 3H(2)O, X = halide, is presented. The structure was determined ab initio from X-ray powder diffraction data and refined by Rietveld methods. The compound crystallizes with the symmetry of space group P2/c with a = 13.589(2) Angstrom, b = 8.8351(9) Angstrom, c = 9.229(1) Angstrom, and beta = 100.79 degrees. The structure consists of inorganic lamellae bridged by phosphono-ethyl-viologen groups. Large pores are formed in this material, which contain one halide ion and three water molecules per formula unit. The free halide ions in these materials are readily exchanged for PtCl(4)(2-)ions. The Pt salt was reduced to give fine metal particles inside the porous solid. These materials produce hydrogen photochemically from water using ultraviolet light. The average rate of H-2 production is 0.15 mL/h with a lower limit quantum yield of 4% based only on the ultraviolet portion of the spectrum in the presence of a sacrificial reductant (EDTA).