Zirconium phosphonate polymerization

Chance B 1991 Optical method Annu. Rev. Biophys. Biophys. Chem. 20 1-28 Granstrom M, Berggren M and Ingan s O 1995 Micrometer- and nanometer-sized polymeric light-emitting diodes Science 267 1479-81 Hanken D G and Com R M 1995 Variable index of refraction ultrathin films formed from self-assembled zirconium phosphonate multilayers Characterization by surface plasma resonance measurements and polarization/modulation FT-IR spectroscopy Anal. Chem. 67 3761-74... 

Lamellar or linear structures are also formed by various other metal ions, such as zinc, (268) manganese, (269) molybdenum, (270) and vanadium (271,272). Among these other solids, vanadium derivatives attracted significant attention due to their potential as industrial catalysts. The structures of the metal phospho-nates are similar to those of the corresponding phosphates, in a manner similar to the zirconium phosphate/phosphonates. Polymerization of phenylphosphonate, for example, with Mo(IV) resulted in a linear double-stranded structure where the phenyl groups are positioned on the outside of the linear structure (273). These othCT metal derivatives are bound to yield many future investigations regarding the fundamental and applied chemistry of layered mataials. 

Reaction of dialkyl H-phosphonates with ZrCl4 yields, depending on the ratio of the reagents, complexes with different coordination numbers at the metal center [421]. These complexes contain chlorine- and phosphonate-type bridges that form a polymeric network. In the course of this reaction, partial dealkylation of the dialkyl H-phosphonates takes place, and results in the formation of Zr-O-P links. On the other hand, the phosphoryl oxygen forms additional donor-acceptor bonds with the zirconium atom. 

Tetravalent metal phosphonates, or MELS (for Molecularly Engineered Layered Structures), provide a novel class of materials that combine many of the properties of incn-ganic metal oxides with the organic functionality more commonly found in functionalized polymeric resins. Early development work on these materials was carried out by Alberti and co-woikers [ref. 1] and Dines et al. [ref. 2]. Synthesis and characterization of related zirconium phosphates that also contain phosphonate groups as pillars have been described by Clearfield [ref 3]. There is a substantial patent estate for tetravalent metal phosphonates, and exclusive rights to this estate are owned by Catalytica [ref 4]. 

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