Controllable Synthesis and Catalytic Performance of Nanocrystals of Rare-Earth-Polyoxometalates

Abstract

Large-scale isolation of nanocrystals of rare-earth-polyoxometalates (RE-POMs) catalysts is important in fundamental research and applications. Here, we synthesized a family of monomeric RE-POMs by the self-assembly of Ta/W mixed-addendum POM {PWTaO} and rare-earth (RE) ions. These RE-POMs with molecular formulas of [RE(HO)]PWTaO· nHO (RE = Y, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) are all electroneutral molecular clusters, insoluble in water and common organic solvents. The electronic structures, electrochemical properties, and catalytic activities of them have been investigated by experimental and computational methods. In particular, based on a mild and controllable synthetic process, a convenient and controllable approach to prepare nanocrystals and self-organized aggregates of these monomers has been developed. They exhibit remarkable heterogeneous catalytic activity for cyanosilylation. Both the increased Lewis acid strength of RE in the title compounds, as indicated by theoretical calculations, and the decreased particle size contribute to their high catalytic performances.

Slow Magnetic Relaxation and Luminescent Properties of Mononuclear Lanthanide-Substituted Keggin-Type Polyoxotungstates with Compartmental Organic Ligands

“… 15 For instance, Ln-containing POMs with accessible coordination sites can behave as effective and recoverable Lewis acid catalysts with enhanced selectivity. 16 , 17 Some recent studies take advantage of the Lewis acid character of 4f metals with the Lewis base behavior of oxygen-rich POM surfaces to design efficient bifunctional catalysts. 18 In addition, their catalytic role in hydrolysis reactions with strong biological implications such as phosphoesterase or protease activity have also been addressed.…”

Oxyfunctionalization of Alkanes Based on a Tricobalt(II)-Substituted Dawson-Type Rhenium Carbonyl Derivative as Catalyst

“…Reviewing the fabrication process of monomer structure crystals, we found that exemplary synthesis strategies is to graft or coordinate organic fragments, hexacoordinated modules, or high-valence metal ions into the lacunary POM to form stable molecular complexes. , In 1980, Klemperer et al first attached M­(CO) n + species to a triangle of oxygen atoms on the surface of polyoxoanion cluster . Later, Finke’s group successfully synthesized two POM-supported metal carbonyl derivatives (PMCDs), [{Re­(CO) 3 }­P 2 W 15 Nb 3 O 62 ] 8– and [{Ir­(CO) 3 }­P 2 W 15 Nb 3 O 62 ] 8– .…”

Research progress on the inhibition of enzymes by polyoxometalates

“…The action mechanism of POMs at the molecular level is completely unknown. Due to the following reasons, there are some difficulties in elucidating the enzyme inhibitory activity of POMs: 12 (1) in most studies, the POM compounds studied are very limited, but the POM structures are changeable, which reduces the universality of the study; (2) the stability of POMs is different, and the stability of the synthesized compounds may be lower than that of the intermediate fragments; (3) whether the inhibition of POMs on enzymes is a competitive mechanism remains to be confirmed.…”

“…When they are used in combination with other components, they can be used as a new multi-functional catalyst and improve the catalytic efficiency. [3][4][5] In view of the unique magnetic properties of polyoxometalates, Brønsted acidity and other characteristics, polyoxometalates play an important role in solving environmental problems, such as toxic gas isolation, wastewater purification, etc. 6 Polyoxometalates can also be used in multifunctional composite materials such as nanomaterials.…”