Polyoxometalate Keggin-type

There is potential in the anti-HIV field. Polyoxometallates of the Keggin type bind to viral envelope sites on cell surfaces and interfere with virus adsorption. Metal-chelating macrocyclic bicyclam ligands are among the most potent inhibitors of HIV ever described, and there is considerable interest in the role of Zn proteins in the viral life cycle. 

Fig. 15. Crystal structure of the Keggin-type polyoxometallate ion [PMo427W7.73O40]6. Adapted from (608).

Oxygenation of alkanes with hydrogen peroxide in homogeneous reactions can be obtained also with Keggin-type iron-substituted polyoxometalates. Evidence against radical reactions has been offered. 

Other classes of catalysts investigated include supported Keggin-type P/Mo/V/O polyoxometalates [14-16], and titania-supported vanadium oxide or V/P/(Mo)/0... 

Various Keggin-type polyoxometalates (POMs) were tested as catalysts for the ODS of gas oil with t-butyl hydroperoxide. Alumina-supported phosphomolybdic acid (H3PMoi2O40) proved to be quite active, yielding sulfur conversion higher than... 

THREE-DIMENSIONAL ORDERED MACROPOROUS HYBRID SILICA MATERIALS FUNCTIONALIZED WITH LACUNARY KEGGIN-TYPE POLYOXOMETALATES PREPARATION AND CHARACTERIZATION... 

Guo Y. H., Yang Y., Hu C. W., Ordered macroporous hybrid silica based on lacunary Keggin-type polyoxometalates preparation, characterization and photochemical behavior, Qn press). 

A. Yoshida, S. Hikichi, N. Mizuno, Acid-base catalyses by dimeric disilicoicosatungstates and divacant y-Keggin-type silicodecatungstate parent Reactivity of the polyoxometalate compounds controlled by step-by-step protonation of lacunary W=O sites, J. Organomet. Chem. 692 (2007) 455. 

Some new structural polyoxometalates were obtained, which are listed in the Table 1. In Table 1, the compound [Bu4N]6[H30]2[Moi304o]2 synthesized by Professor K.L. Tang was a new Keggin-type isopolyoxomolybdate, in which, the [BuaN] cations, [H3O] cations, [Moi304o] anions have different symmetry. Both anions have Keggin-type structures. The structures are based on a central Mo(A)04 slightly distorted tetrahedron surrounded by 12 Mo(B)Oe octahedra. 

Modification of redox and catalytic properties of Keggin-type, Sb-doped P/Mo polyoxometalates in the selective oxidation of isobutane to methacrylic acid control of preparation conditions... 

The current industrial production of methylmethacrylate by the acetone-cyanohydrin process suffers from a number of drawbacks, which make it environmentally unfriendly. In particular, it makes use of a very toxic reactant (HCN) and intermediate (acetone cyanohydrin), and coproduces large amounts of impure ammonium sulphate, contaminated with organic compounds. Among the several alternative synthetic routes which have been proposed, particularly interesting from both the practical and scientific points of view is the single-step oxidation of isobutane to methacrylic acid, intermediate in the synthesis of methylmethacrylate. Several industrial companies have studied this reaction (and the selective oxidation of propane to acrylic acid, as well), and it has been established that the most active and selective catalysts are those which are based on Keggin-type polyoxometalates (POM s), containing phosphorus and molybdenum as the main components [1-18]. 

Sawada, Y. Matsumoto, K. Katsuki, T. Angew. Chem. Int. Ed. 2007, 46, 4559. cat. Keggin-type polyoxometalate... 

---