Variable control of the electronic states of a silver nanocluster protonation/deprotonation of polyoxometalate ligands.

The properties of metal nanoclusters depend on both their structures and electronic states. However, in contrast to the significant advances achieved in the synthesis of structurally well-defined metal nanoclusters, systematic control of their electronic states is still challenging. In particular, stimuli-responsive and reversible control of the electronic states of metal nanoclusters is attractive from the viewpoint of their practical applications.

Synthesis of a phosphomolybdate with a tetranuclear vanadium core by installing vanadium atoms in a lacunary template using the protecting group strategy.

Vanadium-containing phosphomolybdates have outstanding catalytic and electrochemical properties. However, their traditional one-pot synthesis in aqueous media generates a mixture of randomly distributed isomers and undesirable impurities, which has hampered the in-depth study of the catalysis and reaction mechanism of these compounds. Here, the selective synthesis of a tetranuclear vanadium-containing phosphomolybdate, [PV3Mo9O40(VO)]3-, was achieved for the first time by using a pyridine-protected [A-α-PMo9O31(py)3]3- (py = pyridine) as the template.

A protecting group strategy to access stable lacunary polyoxomolybdates for introducing multinuclear metal clusters.

Although metal-containing polyoxomolybdates (molybdenum oxide clusters) exhibit outstanding catalytic properties, their precise synthetic method has not yet been developed. This is mainly because the very low stability of the multivacant lacunary polyoxomolybdates limited their use as synthetic precursors. Here, we present a "protecting group strategy" in polyoxometalate synthesis and successfully develop an efficient method for synthesising multinuclear metal-containing polyoxomolybdates using pyridine as a protecting group for unstable trivacant lacunary Keggin-type polyoxomolybdate [PMoO].

Hexavacant γ-Dawson-type phosphotungstates supporting an edge-sharing bis(square-pyramidal) {OM(μ-O)(μ-OAc)MO} core (M = Mn, Co, Ni, Cu, or Zn).

In aqueous media, the introduction of additional metal species into polyoxometalates (POMs) with multiple vacant sites, such as a hexavacant Dawson-type phosphotungstate, which is of interest for the synthesis of novel metal oxide clusters, is generally difficult because they easily undergo self-condensation and/or structural decomposition. In this study, we succeeded in developing a novel synthetic method to obtain metal-substituted γ-Dawson-type phosphotungstate monomers by introducing metal species into an organic solvent-soluble lacunary phosphotungstate, TBA4H10[α-P2W12O48] (I) (TBA = tetra-n-butylammonium), in organic media. The reaction of I, which possessed two types of vacant sites, i.

Polyoxometalate LUMO engineering: a strategy for visible-light-responsive aerobic oxygenation photocatalysts.

We report the efficient visible-light-responsive photocatalysis of polyoxometalates (POMs) by engineering the lowest unoccupied molecular orbitals (LUMOs). By the introduction of vanadium atoms into the γ-Keggin-type phosphotungstate, a new V3d/W5d mixed LUMO appeared to afford a visible-light-responsive catalyst (I), which showed high photocatalytic activity for aerobic oxygenation of sulfides to sulfoxides.