Zirconium phosphorate frameworks covalently pillared with a bipyridine moiety

This paper describes for the first time the covalent immobilization of 5,5'-bis(dihydroxyphosphoryl)-2,2'-bipyridine (H2O3P-bipy-PO3H2: 1) within the interlayer gallery of alpha and gamma zirconium phosphonate structures. A mixed phosphite/phosphonate compound formulated as Zr(HPO3)(0.8)(O3P-bipy-PO3)(0.6).5.3H(2)O was obtained by reaction of 5,5'-bis(dihydroxyphosphoryl)-2,2'-bipyridine and phosphorous acid with ZrOCl2. 8H(2)O in the presence of HF. Another compound formulated as Zr(PO4)(H2PO4)(0.5)(HO3P-bipy-PO3H)(0.25). 2H2O was prepared by treatment of Zr(PO4)(H2PO4). 2H(2)O (gamma -ZrP) with 5,5'-bis(dihydroxyphosphoryl)-2,2'-bipyridine. These new materials have been characterized by X-ray powder diffraction, IR spectroscopy, thermogravimetry, one- and two-dimensional MAS P-31 NMR spectroscopy, and isothermal Na adsorption-desorption. The mixed a-zirconium phosphonate has a mesoporous area of 330 m(2)/g (pore size, 40 Angstrom) and a microporous surface of 90 m(2)/g whereas the pillared gamma -ZrP phase is essentially microporous (350 m(2)/g). Both materials display a narrow distribution of micropore size centered around 5 Angstrom. The metal binding of the bipyridine moieties remains intact after immobilization as shown by complexation experiments performed by contacting the solids with Cu(I) or Fe(II) methanolic solutions.