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In aqueous solution, a novel triangle-like tungstovanadate estertin derivative K10H10.5[(W4O15(H2O)2){(SnCH2CH2COO)2(V0.75W10.75/V0.25O39)}{{(SnCH2CH2COO)2(μ-OH)}2(SnCH2CH2COO)(VW10O37)}2]·31H2O ((SnR)8-V3W35, R = CH2CH2COO) was assembled by a conventional synthetic method. (SnR)8-V3W35 is composed of one [VW11O39]7− ({VW11}) and two [VW10O37]9− ({VW10}) units connected by eight [Sn(CH2)2COO]2+ groups and a {W4O19} cluster. Interestingly, there exists a pentagonal bipyramid WO7 polyhedral center surrounded by two SnCO5 and three WO6 octahedra, forming a pentagonal {(WO7)W3(SnR)2} cluster in this polyoxometalate (POM), which is also the first example of a pentagonal structure formed by transition metals (TMs) and main group organometals in the POM family. Furthermore, the structure of this organic–inorganic hybrid POM also exhibits the largest number of organotin groups introduced into the POM system. It was characterized with various physico-chemical and spectroscopic methods, including X-ray single crystal and powder diffraction analysis, 119Sn and 51V NMR, IR, thermal gravimetric analysis (TGA), etc. In addition, the catalytic activity of (SnR)8-V3W35 as a mimic of peroxidase was evaluated using o-phenylenediamine (OPD) as a peroxidase substrate. The major factors influencing the oxidation reaction such as pH, the dosage of (SnR)8-V3W35, and concentrations of OPD and H2O2 were mainly studied. (SnR)8-V3W35 exhibits good peroxidase-like catalytic activity. From another perspective, the successful acquisition of (SnR)8-V3W35 further proves the instability and easy reassembly characteristics of TM-sandwich-type tungstovanadates, which also provides a new assembly strategy for synthesizing POM-estertin derivatives. [ABSTRACT FROM AUTHOR]

Development of semiconductor catalysts is an attractive way to solve energy shortage and pollution problems. In this work, a kind of ternary heterojunction nanocomposite g-C3N4/Co3O4/Ag2O was successfully prepared, whose morphology, structure and composition were characterized by TEM, EDS, XRD and XPS analysis. Photocatalytic experiments prove that g-C3N4/Co3O4/Ag2O shows good photodegradation efficiency (98.09%) for RhB under visible light. The free radical capture experiment indicates that the hole, superoxide radical and hydroxyl radical all contribute to the photocatalytic process. In addition, it is found that introducing Ag2O into the composite can efficiently promote the formation of H2O2via the reduction of O2. An electrochemical oxygen reduction reaction (ORR) study further confirms that the value of electron transfer during the ORR is 2.07 for g-C3N4/Co3O4/Ag2O, indicating the promoted two-electron O2 reduction reaction to H2O2. Based on the above results and energy band structures of semiconductors, a possible photocatalysis mechanism is proposed. [ABSTRACT FROM AUTHOR]

In aqueous solution, a novel triangle-like tungstovanadate estertin derivative K 10 H 10.5 [(W 4 O 15 (H 2 O) 2 ){(SnCH 2 CH 2 COO) 2 (V 0.75 W 10.75 /V 0.25 O 39 )}{{(SnCH 2 CH 2 COO) 2 (μ-OH)} 2 (SnCH 2 CH 2 COO)(VW 10 O 37 )} 2 ]·31H 2 O ((SnR)8-V3W35, R = CH 2 CH 2 COO) was assembled by a conventional synthetic method. (SnR)8-V3W35 is composed of one [VW 11 O 39 ] 7- ({VW 11 }) and two [VW 10 O 37 ] 9- ({VW 10 }) units connected by eight [Sn(CH 2 ) 2 COO] 2+ groups and a {W 4 O 19 } cluster. Interestingly, there exists a pentagonal bipyramid WO 7 polyhedral center surrounded by two SnCO 5 and three WO 6 octahedra, forming a pentagonal {(WO 7 )W 3 (SnR) 2 } cluster in this polyoxometalate (POM), which is also the first example of a pentagonal structure formed by transition metals (TMs) and main group organometals in the POM family. Furthermore, the structure of this organic-inorganic hybrid POM also exhibits the largest number of organotin groups introduced into the POM system. It was characterized with various physico-chemical and spectroscopic methods, including X-ray single crystal and powder diffraction analysis, 119 Sn and 51 V NMR, IR, thermal gravimetric analysis (TGA), etc . In addition, the catalytic activity of (SnR)8-V3W35 as a mimic of peroxidase was evaluated using o -phenylenediamine (OPD) as a peroxidase substrate. The major factors influencing the oxidation reaction such as pH, the dosage of (SnR)8-V3W35, and concentrations of OPD and H 2 O 2 were mainly studied. (SnR)8-V3W35 exhibits good peroxidase-like catalytic activity. From another perspective, the successful acquisition of (SnR)8-V3W35 further proves the instability and easy reassembly characteristics of TM-sandwich-type tungstovanadates, which also provides a new assembly strategy for synthesizing POM-estertin derivatives.

Enzyme immobilization is of increasing importance for biocatalysis, for which good supports are critical. Herein, two new Preyssler-type polyoxometalate (POM)-based coordination polymers, namely, {[Cu(H 2 biim) 2 ][{Cu(H 2 biim) 2 (μ-H 2 O)} 2 Cu(H 2 biim)(H 2 O) 2 ]H[({Cu(H 2 biim)(H 2 O) 2 } 0.5 ) 2 ((μ-C 3 HN 2 Cl 2 ){Cu(H 2 biim)} 2 ){Z(H 2 O)P 5 W 30 O 110 }]⋅x H 2 O} n (1: Z=Na, x=9; 2: Z=Ag, x=10; H 2 biim=2,2'-biimidazole) were designed and synthesized. Compounds 1 and 2 exhibit the same skeletons, which contain multiple Cu II complex fragments and penta-supported {ZP 5 W 30 } (Z=Na, Ag) clusters. They were first employed to immobilize horseradish peroxidase (HRP). Results show that compounds 1 and 2 are good supports for HRP immobilization, and exhibit higher enzyme loading, lower loading times, and excellent reusability. The immobilized HRP (HRP/1 or HRP/2) was further applied to detect H 2 O 2 , and good sensitivity, wide linear range, low detection limit, and fast response were achieved. This work shows that POM-based hybrid materials are a new kind of promising support for enzyme immobilization., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In light of the serious challenge of severe global energy shortages, p-type dye-sensitized solar cells (p-DSSCs) have attracted increasing levels of interest. The potential of three Keggin-type transition metal-substituted polyoxometalates, TBA 8 Na 2 [SiW 9 O 37 {Co(H 2 O) 3 }]⋅ 11 H 2 O (SiW 9 Co 3 ), TBA 4 [(SiO 4 )W 10 Mn III 2 O 36 H 6 ]⋅1.5 CH 3 CN⋅ 2 H 2 O (SiW 10 Mn III 2 ), and TBA 3.5 H 5.5 [(SiO 4 )W 10 Mn III/IV 2 O 36 ]⋅ 10 H 2 O⋅0.5 CH 3 CN (SiW 10 Mn III/IV 2 ) has been explored as pure inorganic dye photosensitizers for p-DSSCs (TBA=(n-C 4 H 9 ) 4 N + ). The three dyes show overall conversion efficiencies of 0.038, 0.029, and 0.027 %, respectively, all of which are higher than that of coumarin 343 (0.017 %). These polyoxometalates are the first three pure inorganic dyes reported for use with p-DSSCs and therefore demonstrate a new strategy for designing efficient dyes, especially pure inorganic dyes. Moreover, they broaden the range of applications for polyoxometalates., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)