Polyoxometallate species

Some fimctionalized materials have also been prepared by coprecipitation at low supersaturation. A perylene chromophore, for example, has been intercalated into LDH in an attempt to prepare stabihzed pigments [40]. Catalyt-ically active species have also been introduced into the interlayers of LDHs by direct synthesis, e.g. the intercalation of (PWi204o) or (SiWi204o) gives catalysts or catalyst precursors containing interlayer polyoxometalate anions [41]. Vein et al. reported the synthesis of Zr-containing LDH-Hke... 

The intercalation of anionic species into LDHs is an interesting alternative for the immobilization of catalytic complexes. Special attention is being paid to LDHs containing bulky and stable anions, e.g. polyoxometalates (POMs), since they can give rise to a wide range of microporous materials [4]. Many years ago, Pinnavaia et al. reported the intercalation of POM anions into LDHs, and found that the products showed significant photo-catalytic activity in the oxidation of isopropanol to acetone in the presence... 

There are two closely related aspects here, concerning species where an oxoanion such as sulfate or chromate forms a recognizably classical coordination complex and polyoxometallates where one, two, or many iron centers are incorporated in a multi-oxide-bridged polynuclear complex. 

The formation of sandwich-type POMs from solutions of metal cations and triva-cant heteropolytungstate species may alternatively be viewed as means to sequester cations from solution [116]. The question then arises if reversible dissociation of the metal cations from the multidentate ligands is possible as well. The sequestration and subsequent release of metal cations under appropriate conditions is of considerable interest in waste decontamination technology as well as in medicine [124]. Following these ideas, the demetallation process of ten multi-iron Wells-Dawson polyoxometalates is studied by cyclic... 

Another possible electrocatalytic process is that related to a surface-bound molecule which can give rise to a two-electron reaction. In these conditions, the coupling of the catalytic reaction in the presence of an adequate species in solution can lead to different mechanistic schemes from which the elucidation of the global reaction path is not immediate. This situation matches the behavior of a great number of inorganic catalysts (such polyoxometallates or ion complexes) [86, 98] and biological molecules (enzymes, proteins, oligonucleotides, etc.) [79, 80], for which there is a lack of theoretical basis which enables a clear classification of the different possibilities that can be encountered. 

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