Toward High Power-High Energy Sodium Cathodes: A Case Study of Bicontinuous Ordered Network of 3D Porous Na3 (VO)2 (PO4 )2 F/rGO with Pseudocapacitance Effect.

Developing high power-high energy electrochemical energy storage systems is an ultimate goal in the energy storage field, which is even more difficult but significant for low-cost sodium ion batteries. Here, fluoride is successfully prepared by the electrostatic spray deposition (ESD) technique, which greatly expands the application scope of ESD. A two-step strategy (solvothermal plus ESD method) is proposed to construct a bicontinuous ordered network of 3D porous Na3 (VO)2 (PO4 )2 F/reduced graphene oxide (NVOPF/rGO). This two-step strategy makes sure that NVOPF can be prepared by ESD, since it avoids the loss of F element during synthesis. The obtained NVOPF particles are as small as 15 nm, and the carbon content is only 3.5% in the final nanocomposite. Such a bicontinuous ordered network and small size of electroactive particles lead to the significant contribution of the pseudocapacitance effect to sodium storage, resulting in real high power-high energy sodium cathodes. The cathode exhibits excellent rate capability and cycling stability, whose rate performance is one of the best ever reported in both half cells and full cells. Moreover, this work provides a general and promising strategy for developing high power-high energy electrode materials for various electrochemical energy storage systems.

Correction: Diversified polyoxovanadate derivatives obtained by copper(i)-catalysed azide-alkyne cycloaddition reaction: their synthesis and structural characterization.

Correction for 'Diversified polyoxovanadate derivatives obtained by copper(i)-catalysed azide-alkyne cycloaddition reaction: their synthesis and structural characterization' by Hongli Jia et al., Dalton Trans., 2018, 47, 577-584.

A Series of Weakley-type Polyoxomolybdates: Synthesis, Characterization, and Magnetic Properties by a Combined Experimental and Theoretical Approach.

Using DCC as the dehydrating agent, a series of Weakley-type polyoxomolybdates [Bu4N]3{Ln[Mo5O13(OMe)4(NO)]2} (Ln = Tb, Dy, Ho, Er) were synthesized in a one-pot reaction and structurally characterized by elemental, IR, UV-vis analysis, PXRD, and single-crystal X-ray diffraction. Furthermore, the static and dynamic measurements were utilized to investigate their magnetic performances. Typically, slow relaxation of magnetization was observed for Dy analogues with an energy barrier for the reversal of the magnetization of 50 K, which is the highest barrier height observed on the polyoxomolybdates-based single-molecule magnets (SMMs). For a deep understanding of the appearance of the SMM behavior on Weakley-type polyoxomolybdates series, ab initio calculations on {Dy[Mo5O13(OMe)4(NO)]2}3- have been conducted.

Diversified polyoxovanadate derivatives obtained by copper(i)-catalysed azide-alkyne cycloaddition reaction: their synthesis and structural characterization.

In this work, we confirmed that the copper-catalysed azide-alkyne cycloaddition (CuAAC) reaction is an effective method for the organic-functionalization of polyoxometalates (POMs). Herein, for the first time, four novel 1,2,3-triazole functionalized polyoxovanadate (POV) organic-inorganic hybrids, (Bu4N)2[V6O13{(OCH2)3C5H6N3O}2]·1.5CH3CN 2, (Bu4N)2[V6O13{(OCH2)3C7H8N3O2}2]·2CH3CN 3, (Bu4N)2[V6O13{(OCH2)3C11H10N3}2] 4 and (Bu4N)2[V6O13{(OCH2)3C10H7N3Cl}2] 5 were prepared through the CuAAC reaction using the azide functionalized hexavanadate, (Bu4N)2[V6O13{(OCH2)3CCH2N3}2]·2.5CH3CN 1, as the precursor, where CuI was used as the catalyst and N,N-diisopropylethylamine (DIPEA) as a stabilizer for CuI. All the four compounds were structurally and compositionally characterized by single-crystal X-ray diffraction, elemental analyses, powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), 1H NMR, ESI-MS, UV-Vis and thermogravimetric analysis (TGA).

Tosylation of alcohols: an effective strategy for the functional group transformation of organic derivatives of polyoxometalates.

Recently, the organic functionalization of polyoxometalates (POMs) has drawn increasing interest, and an easy and effective route to achieve organic derivatives is of great importance. Herein, the first reported synthesis of a tosyl ester derivative of the polyoxometalate (Bu4N)2[V6O13{(OCH2)3CCH2SO3C7H4}2]·2.5CH3CN (compound 1) was performed by using DMAP as an activating reagent and triethylamine as an HCl scavenger. The tosyl ester was transformed into an azide or halide group by using sodium azide or sodium bromide, respectively, as the nucleophilic agent. Two derivatives of POMs, (Bu4N)2[V6O13{(OCH2)3CCH2N3}2]·4CH3CN (compound 2) and (Bu4N)2[V6O13{(OCH2)3CCH2Br}2] (compound 3), were easily obtained. All the compounds were structurally and compositionally characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, NMR spectroscopy, ESI-MS, UV-Vis spectroscopy and TGA. This work provides a new route for the functional group transformation of organic derivatives of polyoxometalates.

Buildup of Redox-Responsive Hybrid from Polyoxometalate and Redox-Active Conducting Oligomer: Its Self-Assemblies with Controllable Morphologies.

A redox-responsive hybrid of polyoxometalate and conducting oligomer including its self-assemblies with controllable morphologies are reported. To this end, a hybrid molecule, containing a Lindqvist hexamolybdate as the polar head group and N,N'-bis(4'-amino-2,6-dimethylphenyl)-1,4-quinonediimine as the redox-responsive and aggregating group, is prepared. This hybrid exhibits redox-responsive behavior with controllable assembling morphological transition from spherical vesicles to short cylindrical vesicles. Besides, the hybrid-based self-assemblies are transferred to the surface, thus the surface wettability can be well-tuned owing to the morphological transitions of the self-assemblies. By marrying conducting materials with polyoxometalate chemistry, this research opens a new horizon of polyoxometalate-based self-assembled systems with potential applications in functional materials.

A simple synthetic route to polyoxovanadate-based organic-inorganic hybrids using EEDQ as an ester coupling agent.

A reaction strategy for the post-functionalization of hexavanadate derivatives is presented herein. In this study, five polyoxovanadate-based organic-inorganic hybrids TBA2[V6O13{(OCH2)3CCOO(CH2)15CH3}2] (2), TBA2[V6O13{(OCH2)3CCOO(CH2)8CH[double bond, length as m-dash]CH2}2] (3), TBA2[V6O13{(OCH2)3CCOOCH2CF3}2] (4), TBA2[V6O13{(OCH2)3CCOO(CH2CH2O)3CH3}2] (5), and TBA2[V6O13{(OCH2)3CCOO(CH2)12OH}2]·2CH3CH2OH (6) were successfully synthesized via esterification of carboxylic acid groups-containing TBA2[V6O13{(OCH2)3CCOOH}2] (1) with five alcohols possessing different functional groups. These hybrids were characterized by single crystal X-ray diffraction, IR, ESI-MS, 1H and 13C-NMR spectroscopies, and elemental analysis. Moreover, the formation of large vesicles was observed in a mixed solution of compound 2 due to its surfactant-like structure.

Label-free colorimetric detection of mercury via Hg(2+) ions-accelerated structural transformation of nanoscale metal-oxo clusters.

Mercury and its compounds are known to be extremely toxic but widely distributed in environment. Although many works have been reported to efficiently detect mercury, development of simple and convenient sensors is still longed for quick analyzing mercury in water. In this work, a nanoscale metal-oxo cluster, (n-Bu4N)2[Mo5NaO13(OCH3)4(NO)], (MLPOM), organically-derivatized from monolacunary Lindqvist-type polyoxomolybdate, is found to specifically react with Hg(2+) in methanol/water via structural transformation. The MLPOM methanol solution displays a color change from purple to brown within seconds after being mixed with an aqueous solution containing Hg(2+). By comparing the structure of polyoxomolybdate before and after reaction, the color change is revealed to be the essentially structural transformation of MLPOM accelerated by Hg(2+). Based on this discovery, MLPOM could be utilized as a colorimetric sensor to sense the existence of Hg(2+), and a simple and label-free method is developed to selectively detect aqueous Hg(2+). Furthermore, the colorimetric sensor has been applied to indicating mercury contamination in industrial sewage.

A redox active triad nanorod constructed from covalently interlinked organo-hexametalates.

A novel nanorod-like inorganic-organic hybrid compound based on polyoxometalate architectures and organic linkers was successfully synthesized, which exhibits reversible reduction-oxidation properties and fascinating photochromism under sunlight illumination.

Spontaneous stepwise self-assembly of a polyoxometalate-organic hybrid into catalytically active one-dimensional anisotropic structures.

An inorganic-organic hybrid surfactant with a hexavanadate cluster as the polar head group was designed and observed to assemble into micelle structures, which further spontaneously coagulate into a 1D anisotropic structure in aqueous solutions. Such a hierarchical self-assembly process is driven by the cooperation of varied noncovalent interactions, including hydrophobic, electrostatic, and hydrogen-bonding interactions. The hydrophobic interaction drives the quick formation of the micelle structure; electrostatic interactions involving counterions leads to the further coagulation of the micelles into larger assemblies. This process is similar to the crystallization process, but the specific counterions and the directional hydrogen bonding lead to the 1D growth of the final assemblies. Since most of the hexavanadates are exposed to the surface, the 1D assembly with nanoscale thickness is a highly efficient heterogeneous catalyst for the oxidation of organic sulfides with appreciable recyclability.