RESUMEN
We present a novel, self-assembled nanostructure with selective photocatalytic activity formed from anionic polyoxometalate clusters and cationic dendrimers by electrostatic self-assembly. The association of the components in aqueous solution is driven by ionic interaction and steric factors yielding stable aggregates of a defined size with a coil-like structure. The assemblies show high potential for the application in solar-energy conversion systems due to their enhanced and substrate specific photocatalytic activity.
RESUMEN
The synthesis, crystallographic analysis and full characterization of the Cu(i) complex-functionalized Anderson polyoxomolybdate anions (nBu4N)[MMo6O18((OCH2)3CNCH(C47H37N2P2OCu)2)] (M = Mn3+, Fe3+, Co3+) is reported. For the first time, direct crystallographic evidence for the covalent attachment of a photoactive metal complex to an organo-functionalized polyoxometalate is obtained. Initial electrochemical and photochemical studies report fundamental properties and solution stability of the compounds.
RESUMEN
The covalent functionalization of metal oxide surfaces with organic ligands gives unique organic-inorganic hybrids. Here we report a bifunctional organic tether combining a phosphonate for metal oxide anchoring with an organic azide for attachment of organic groups. Stable binding of the tether to molecular and solid-state metal oxides is demonstrated and the subsequent "CLICKability" of the TiO2-anchored tether is shown. The phosphonate-azide reported could in future allow the general linkage of functional organic groups to metal oxides.
RESUMEN
A comparative study investigating the effects of metal substitution on the photocatalytic activity of metal oxide cluster anions is presented. The study shows that metal functionalization can be used to alter the photochemical properties of monolacunary tungstate - based Keggin clusters (α-[TM(H2O)SiW11O39](n-) (M = Co(2+), Cu(2+), Ni(2+), Mn(2+))). It is demonstrated that the photoactivity for the photooxidation of the model pollutant basic blue 41 is dependent of the type of metal employed and increases in the order Co < Cu < Ni < Mn under aerobic conditions and 390 nm monochromatic irradiation. A significant increase of the reaction rate is observed under aerated conditions compared with de-aerated conditions, suggesting that oxygen serves as a re-oxidant for the reduced clusters. Radical scavenging experiments suggest that the photocatalysis proceeds via formation of hydroxyl radicals.
RESUMEN
The thermochromic and solvatochromic properties of Lindqvist metal oxide clusters [V(x)M(6-x)O19](n-) (x = 0, 1, 2, M = Mo, W) are reported. The cluster anions show pronounced changes of their electronic structure depending on their chemical environment (e.g. solvent polarity, temperature). These are rationalized using experimental and theoretical methods. A combined density functional theory and (51)V-NMR study suggests that temperature-dependent changes in the structural dynamics of the metal oxide framework are the underlying cause for the observed thermochromism. The results might open new avenues for the design of molecular optical sensors.
