Opioid Drug Detection in Hair Samples Using Polyoxometalate-Based Frameworks

A series of two-dimensional (2D) polyoxometalate-based frameworks, [Ln₃(PDA)₃(H₂O)₆(PMo₁₂O₄₀)]·xH₂O (Ln = La (1); Ce (2); Pr (3); Nd (4); PDA = 1,10-phenanthroline-2,9-dicarboxylate), have been synthesized and structurally characterized by various analytical techniques. Single-crystal X-ray diffraction reveals that 1-4 have a unique 2D layer structure in which Keggin anions have coordinated upward and downward the plane, and this feature makes them suitable candidates for surface binding of common drugs via supramolecular and electrostatic interactions. Also, the ability of 1-4 (as the first polyoxomolybdate-containing frameworks) as sorbents for the extraction and quantitative determination of opioid drugs (morphine, methadone, and pethidine) was investigated by using dispersive micro-solid-phase extraction (D-μSPE) and high-performance liquid chromatography (HPLC). The method showed wide linear ranges in the range of 0.3 to 300 ng mg^-1 and low limits of detection (LODs) ranged from 0.1 to 0.2 ng mg^-1 of hair.

A Keggin-type polyoxomolybdate-based crystalline material formed by hydrothermal transformation: photo/electro-catalytic properties and mechanism study

This study constructs a POM-based crystalline material of [(SiMo12O40)Cu6(2,2′-bipy)6(Mo6O22)] (1). The photocatalytic MB degradation and electrocatalytic nitrite reduction properties of complex 1 are systematically studied for the first time.

Tungsten and Molybdenum Heteropolyanions with Different Central Ions—Correlation between Theory and Experiment

Density functional theory calculations were carried out to investigate the electronic structures of Keggin-typed [XMo₁₂O₄₀]ⁿ⁻ and [XW₁₂O₄₀]ⁿ⁻ anions with different heteroatoms (X = Zn²⁺, B³⁺, Al³⁺, Ga³⁺, Si⁴⁺, Ge⁴⁺, P⁵⁺, As⁵⁺, and S⁶⁺). The influence of solvent on redox properties of heteropolyanions was discussed. For [XW₁₂O₄₀]ⁿ⁻ systems two linear correlation: first, between the experimental redox potential and energies of LUMO orbital; and second, between the experimental redox potential and total energy interaction (calculated between internal tetrahedron (XO₄ⁿ⁻), and rest of Kegging anion skeleton, (W₁₂O₃₆)) were designated. Taking into account the similarity of XW₁₂O₄₀ⁿ⁻ and XMo₁₂O₄₀ⁿ⁻ systems (in geometry and electronic structure), the estimated redox potential of molybdenum heteropolyanions (with X being p block elements) in different solvent were proposed.

Application of polyoxometalates in photocatalytic degradation of organic pollutants

Organic pollutants are highly toxic, accumulative, and difficult to degrade or eliminate. As a low-cost, high-efficiency and energy-saving environmental purification technology, photocatalytic technology has shown great advantages in solving increasingly serious environmental pollution problems. The development of efficient and durable photocatalysts for the degradation of organic pollutants is the key to the extensive application of photocatalysis technology. Polyoxometalates (POMs) are a kind of discrete metal-oxide clusters with unique photo/electric properties which have shown promising applications in photocatalytic degradation. This review summarizes the recent advances in the design and synthesis of POM-based photocatalysts, as well as their application in the degradation of organic dyes, pesticides and other pollutants. In-depth perspective views are also proposed in this review.

A Tellurium-Substituted Heteropolyniobate with Unique π-π Stacking and Ionic Conduction Property

A tetratellurium-substituted heteropolyoxoniobate with the formula K₂H[Cu(phen)(H₂O)]₄[Cu(phen)]₂[(LiNb₈Te₄O₄₀)]·34H₂O (1; phen = 1,10-phenanthroline) was hydrothermally prepared and structurally characterized. The compound represents the first hexavalent tellurium-substituted Keggin-type polyoxometalate (POM) so far. What is more, the POM cluster in 1 can elaborately self-assemble into a stable supramolecular framework with an ion conduction property through unique intermolecular π-π stacking.

Polyoxometalate-based metal–organic frameworks for heterogeneous catalysis

POM-based MOFs simultaneously possessing the virtues of POMs and MOFs exhibit excellent heterogeneous catalytic properties.

CNTs synthesized with polyoxometalate-based metal–organic compounds as catalyst precursors via the CVD method and their adsorption performance towards organic dyes

CNTs were synthesized with POM-based compounds as catalyst precursors via the CVD method, and they possess a high adsorption capacity towards organic dyes.

Visible-light CO2 photoreduction of polyoxometalate-based hybrids with different cobalt clusters

Two novel high-nuclear cobalt-based polyoxometalates can effectively improve photocatalytic activities for CO₂ photoreduction under visible light.

A silicotungstate-based copper–viologen hybrid photocatalytic compound for efficient degradation of organic dyes under visible light

An efficient visible light responsive compound [Cu(PBPY)]₂[SiW₁₂O₄₀] (1) has been constructed by integrating a silicotungstate cluster into the copper–viologen framework. It shows high photocatalytic efficiency for the degradation of dye pollutants.

A robust polyoxometalate-templated four-fold interpenetrating metal–organic framework showing efficient organic dye photodegradation in various pH aqueous solutions

A polyoxometalate-templated four-fold interpenetrating 3-D MOF of 1 acts as a photocatalyst, which can efficiently degrade the organic dyes under UV-Vis light irradiation in aqueous solutions over a wide pH range.

Aminated Graphene Oxide Impregnated with Photocatalytic Polyoxometalate for Efficient Adsorption of Dye Pollutants and Its Facile and Complete Photoregeneration

Contamination of industrial sewage by organic dye pollutants is one of the most common challenges to the daily life. De-contamination can be achieved by adsorption and photodegradation of the pollutants. However, the former technique is generally limited by the poor loading capacity of the adsorbent and/or the difficulty in its regeneration for reuse, while the latter often suffers from sluggish reaction kinetics and thus requires long reaction time and powerful light source to be successful. Herein, a solution to these challenges by creating nanocomposites featuring porous diamine-functionalized graphene oxide (FGO) impregnated with photocatalytically active polyoxometalates (POMs) is presented. Cross-linking of GO via diamination not only generates porous structures with positively charged interior that attracts and stabilizes the anionic POM guests, but also modulates the GO bandgap. The introduction of POMs improves loading capacity of FGO for cationic dyes and promotes effective separation of electron-hole pair by trapping and transferring photogenerated electron. Thus, the two components act in synergy to result in much improved adsorption of certain common organic dyes as well as enhanced oxidative degradation by both the GO host and the POMs that lead to complete regeneration of the adsorbents without compromising their performance in multiple rounds of reuse.

Two unusual 3D honeycomb networks based on Wells–Dawson arsenomolybdates with d10 transition-metal-pyrazole connectors

Two unusual 3D honeycomb networks based on Wells–Dawson arsenomolybdates were first reported, which have highly efficient catalytic ability for the degradation of organic dyes under UV irradiation and obvious electrocatalytic activities for the reduction of H₂O₂.