Two new polyoxometalate-based metal-organic complexes for the detection of trace Cr(VI) and their capacitor performance

Two new Keggin-type polyoxometalate (POM)-based metal-organic complexes (MOCs) H3[Cu2(4-dpye)2(PMo12O40)] (1) and H[Cu2(4-Hdpye)2(PMo12O40)(H2O)4]·2H2O (2) were constructed with a new N,N'-bis (4-pyrimidinecarboxamido)-1,2-ethane (4-H2dpye) ligand by the hydrothermal/solvothermal method. Complex 1 was a 2D layered structure constructed from 1D metal-organic chains [Cu(4-dpye)]n and Keggin-type [PMo12O40]3- polyoxoanions. Complex 2 displays a 3D supramolecular framework formed by discrete [PMo12O40]3- polyoxoanions and binuclear metal-organic loops [Cu2(4-Hdpye)2]. The electrocatalytic behaviors of carbon paste electrodes modified by complexes 1 and 2 (1-CPE and 2-CPE) were investigated. The 1-CPE and 2-CPE were used as electrochemical sensors to detect trace Cr(vi), and the low limits of detection (LOD) are 1.27 × 10-7 M for 1 and 1.71 × 10-7 M for 2, which are lower than the maximum allowable concentration of Cr(vi) in drinking water specified by the World Health Organization (WHO). In addition, the performances of complexes 1 and 2 modified carbon cloth electrodes (1-CC and 2-CC) as supercapacitor materials have also been studied. The influence of the structure on electrocatalytic and capacitor performances is discussed.

Syntheses, structures and catalytic properties of Evans–Showell-type polyoxometalate-based 3D metal–organic complexes constructed from the semi-rigid bis(pyridylformyl)piperazine ligand and transition metals

Two 3D Evans–Showell-type POM-based different transition metals–bis-pyrazine–bis-amide complexes act as heterogeneous catalysts for the oxidation of benzyl alcohol.

A novel polyoxometalate-based metal–organic nanotube framework templated by twin-Dawson clusters: synthesis, structure and bifunctional electrocatalytic properties

A novel polyoxometalate-based metal–organic nanotube framework templated by twin-Dawson clusters was synthesized, which exhibits high-performance bifunctional electrocatalytic activities toward reduction of bromate and oxidation of ascorbic acid.

Two-dimensional light-emitting materials: preparation, properties and applications

We review the recent development in two-dimensional (2D) light-emitting materials and describe their preparation methods, optical/optoelectronic properties and applications.

Phosphomolybdate assembly as a low-cost catalyst for the reduction of toxic Cr(vi) in aqueous solution

A fully reduced phosphomolybdate hybrid compound was active as a heterogeneous molecular catalyst to reduce toxic Cr(vi) to nontoxic Cr(iii) using formic acid under mild conditions. The activation energy was calculated to be 78.5 kJ·mol⁻¹.

Diverse polyoxometalate-based metal–organic complexes constructed by a tetrazole- and pyridyl-containing asymmetric amide ligand or its in situ transformed ligand

Four metal–organic complexes constructed from different polyoxoanions and a tetrazole- and pyridyl-containing asymmetric amide ligand or its in situ transformed ligand have been synthesized and structurally characterized.

A series of Anderson-type polyoxometalate-based metal–organic complexes: their pH-dependent electrochemical behaviour, and as electrocatalysts and photocatalysts

Seven novel polyoxometalate-based metal–organic complexes are synthesized and structurally characterized, exhibiting high electrochemical sensitivity to pH and photocatalytic activities for the degradation of organic dyes under UV irradiation.

Hydrothermal assembly of various dimensional pure-inorganic copper–molybdenum frameworks

CMF-1 to CMF-3 were firstly obtained by using [Mo₇O₂₄]⁶⁻ and Cu tetrahedra, and all showed excellent performance for the degradation of methylene blue.

Two copper(i) cyanide coordination polymers modified by semi-rigid bis(benzimidazole) ligands: syntheses, crystal structures, and electrochemical and photocatalytic properties

Two Cu(i) cyanide complexes with semi-rigid bis(benzimidazole) ligands were synthesized and characterized. Both complexes manifest photocatalytic activities for the degradation of methylene blue.

Polyoxometalate-based supramolecular architecture constructed from a purely inorganic 1D chain and a metal–organic layer with efficient catalytic activity

A new polyrotaxane structure constructed from a pure inorganic polyoxometalate-based 1D chain, exhibited efficient catalytic activity for desulfurization and electrocatalytic redox activity.

A molecular crown analogue templated by Keggin polyanions: synthesis, structure, and electrochemical and luminescent properties

A hybrid compound, [CuI 4(bpmb)4][PWVI 11WVO40] (1) (bpmb = 1,4-bis(pyrazol-1-ylmethyl)benzene), has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction analysis, infrared spectroscopy, elemental analyses and powder X-ray diffraction. In compound 1 crown-like [Cu4(bpmb)4]4+ macrocycles templated by Keggin-type [PWVI 11WVO40]4− polyanions (abbreviated PW12) exist. Supramolecular layers are formed by intermolecular hydrogen bonding interactions of discrete crown-like [Cu4(bpmb)4]4+ macrocycles and [PWVI 11WVO40]4− polyanions. The electrochemical and luminescence properties of compound 1 were investigated.

The key role of -CH3 steric hindrance in bis(pyrazolyl) ligand on polyoxometalate-based compounds

Through using two kinds of bis(pyrazolyl) ligands, four polyoxometalate (POM)-based compounds were hydrothermally synthesized and structurally characterized, [Ag3(Hbhpe)2(H2O)(H2PMo12O40)]·H2O (1), [Ag(H2bdpm)2(H2PW12O40)]·4H2O (2), [Ag6(H2bdpm)6(HPW(VI)8W(V)4O40)]·2H2O (2) and [Ag4(H2bdpm)4(H2P2W18O62)]·3H2O (4) (H2bhpe = 1,2-bis(1-H-pyrazolate)ethane, H2bdpm = 1,1'-bis(3,5-dimethyl-1H-pyrazolate)methane). In compound 1, the Ag-Hbhpe subunit is a 2D layer containing large penta-membered cycles and small tri-nuclear Ag(I) clusters. The Keggin anions covalently float on the large cycles. In compound 2, the Keggin anions are fused by [Ag(H2bdpm)2](+) subunits to form a 1D chain. Compound contains hexa-membered metal-organic cycles, which are further linked by Keggin anions to build a 1D chain. Adjacent chains share the Ag(I) ions to construct a 3D framework of 3. Compound 4 exhibits a wavy double-track chain structure, with the Wells-Dawson anions covalently suspended up and down this chain. The steric hindrance of -CH3 groups in H2bdpm leads to the formation of mono-nuclear Ag(I) subunits in 2 - 4. The influence of -CH3 steric hindrance in bis(pyrazolyl) ligands on the structures of 1 - 4 is discussed. The electrochemical and photocatalytic properties of the title compounds have been studied.

Architectural chemistry of polyoxometalate-based coordination frameworks constructed from flexible N-donor ligands

Polyoxometalate-based coordination frameworks (POMCFs) constructed from flexible N-donor ligands can exhibit diverse properties and fascinating architectures, extending the families of material chemistry and structural chemistry.

Application of flexible bis-pyrazine–bis-amide ligands to construct various polyoxometalate-based metal–organic complexes

Five novel polyoxometalates-based metal–organic complexes constructed from different types of polyanions and flexible bis-pyrazine–bis-amide ligands with different spacer lengths have been hydrothermally synthesized and structurally characterized.

Assembly of organic–inorganic hybrid materials constructed from polyoxometalate and metal–1,2,4-triazole units: synthesis, structures, magnetic, electrochemical and photocatalytic properties

A family of organic–inorganic hybrids built by Keggin/Dawson POMs with metal–1,2,4-triazole units has been synthesized through modulating the pH value.

Two novel Anderson-type polyoxometalate-based metal–organic complexes with high-efficiency photocatalysis towards degradation of organic dyes under UV and visible light irradiation

Two novel Anderson-type polyoxometalate-based metal–organic complexes constructed from two bis-pyridyl-bis-amide ligands have been hydrothermally synthesized, showing excellent photocatalytic activities toward the degradation of dyes.

A novel polyoxometalate templated microporous metal–organic framework with electrochemical properties

A novel Wells–Dawson polyoxometalate-templated 3D microporous metal–organic framework with a rare 8⁶ uniform net was obtained, which showed electrochemical properties.

Polyoxometalate-directed assembly of various multinuclear metal–organic complexes with 4-amino-1,2,4-triazole and selective photocatalysis for organic dye degradation

Five POM-based metal–organic complexes ranging from 0D trinuclear cluster, 1D chain, 2D network, to 3D framework have been successfully prepared in the presence/absence of citric or boric acid.

Assembly and photocatalysis of two novel 3D Anderson-type polyoxometalate-based metal–organic frameworks constructed from isomeric bis(pyridylformyl)piperazine ligands

Two 3D Anderson-based MOFs constructed from two isomeric bis(pyridylformyl)piperazine have been synthesized. The isomeric ligands and Anderson-type polyanions play key roles in the construction of the final frameworks.