Topic
Polyoxometalate
About: Polyoxometalate is a research topic. Over the lifetime, 3493 publications have been published within this topic receiving 94123 citations. The topic is also known as: POM.
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TL;DR: In this paper, a new nanocomposites based on Pt modified [PW11NiO39]5−@reduced graphene oxide (rGO) and Pt-modified multi-wall carbon nanotubes (CNT) are presented.
40 citations
TL;DR: Keggin polyphosphotungstate cluster was captured by a porous molecular ring with light sensitizing TPT molecules as connectors and copper ions as nodes, demonstrating efficient heterogeneous photocatalytic behavior for the degradation of methyl orange in near-neutral conditions.
40 citations
TL;DR: In this paper, a phase-separable catalysts for selective oxidation of thioethers and thiophenes to the corresponding sulfoxides or sulfones was introduced.
Abstract: Synthesis of various organic–inorganic polyoxometalate based salts composed of sulfonated pyridinum cations and the Keggin tungstophosphate anion (PW12O403−) and their subsequent application in the oxidation of methyl phenyl sulfide with hydrogen peroxide in aqueous media was reported. Special attention was paid to the temperature-dependent solubility of the salts as a function of the organic cation in water. Cyclic voltammetry was further used for the investigation of the redox behavior of these catalysts. Based on these properties, a novel thermoregulated phase-separable catalyst was introduced and successfully used for the selective oxidation of thioethers and thiophenes to the corresponding sulfoxides or sulfones. Catalytic oxidation of the sulfur-containing model oil (methyl phenyl sulfide, dibenzothiophene and thiophene) was also studied under optimized conditions. In both cases, excellent conversion and selectivity were obtained in relatively short reaction times. This novel catalyst showed the characteristic of homogeneous reaction at ambient temperatures and phase-separation at lower temperatures. By simple decantation, the catalyst could be easily separated from the products upon cooling of the reaction mixture and could be reused several times with high recycling efficiency.
40 citations
TL;DR: Dual signaling responses of turbidity and fluorescence are observed simultaneously in the detection of urease and heavy metals based on pH-induced disassembly of the supramolecular spheres during the biochemical events in aqueous solution.
Abstract: We report fabrication, characterization, and potential applications of polyoxometalate (POM)/ionic liquid (IL) supramolecular spheres in water for the first time. These supramolecular spheres have highly ordered structures and show excellent reversible self-assembly and tunable photoluminescence properties, which can be manipulated by adjusting pH of the aqueous solution. Specifically, the formation of POM/IL supramolecular spheres results in quenching of fluorescence emitted by Eu-POM because hopping of the d1 electron in the POM molecule is blocked by hydrogen bond existing between the oxygen atom of POM and the carboxylic acid group of IL. However, the fluorescence can be completely recovered by gradually increasing pH of the aqueous solution due to the pH-induced deprotonation of the carboxylic acid group of IL, which results in disassembly of the fabricated supramolecular spheres. Applications of these stimuli-responsive photoluminescent POM-based supramolecular materials are demonstrated in biological media. Dual signaling responses of turbidity and fluorescence are observed simultaneously in the detection of urease and heavy metals based on pH-induced disassembly of the supramolecular spheres during the biochemical events in aqueous solution. In addition, guest molecules are encapsulated into the supramolecular spheres, and controlled release of these entrapped molecules is demonstrated in the presence of external stimuli. This study shows potential of stimuli-responsive POM/IL supramolecular materials in biological applications.
40 citations
TL;DR: In this paper, a series of polyoxometalate (POM) intercalated layered double hydroxides (LDHs) have been widely used as heterogeneous catalysts.
Abstract: The polyoxometalate (POM) intercalated layered double hydroxides (LDHs) have been widely used as heterogeneous catalysts. However, the application of POM–LDHs as bifunctional catalysts for cascade reaction has seldom been studied compared to the noble-metal-based catalysts. Herein, a series of POM–LDHs catalysts of Tris–LDH–X4(PW9)2 (X=Mn, Fe, Co, Ni, Cu, and Zn; Tris=Tris(hydroxymethtyl)aminomethane) have been prepared. The efficacy of Tris–LDH–Zn4(PW9)2 as efficient bifunctional catalyst has been demonstrated for cascade reactions involving oxidation of benzyl alcohol to benzaldehyde followed by Knoevenagel condensation with ethyl cyanoacetate to produce benzylidene ethyl cyanoacetate. The combination of POM's redox/acidic sites and LDHs's basic sites led to a composite catalyst with excellent activity (99 %) and selectivity (≥99 %) under mild and soluble-base-free conditions. This work offers a new design strategy for the fabrication of efficient bifunctional catalysts for the promotion of one-pot cascade reactions.
40 citations