Spiral Square Nanosheets Assembled from Ru Clusters

Spiral two-dimensional (2D) nanosheets exhibit unique physical and chemical phenomena due to their twisted structures. While self-assembly of clusters is an ideal strategy to form hierarchical 2D structures, it is challenging to form spiral nanosheets. Herein, we first report a screw dislocation involved assembled method to obtain 2D spiral cluster assembled nanosheets (CANs) with uniform square morphology. The 2D spiral Ru CANs with a length of approximately 4 μm and thickness of 20.7 ± 3.0 nm per layer were prepared via the assembly of 1-2 nm Ru clusters in the presence of molten block copolymer Pluronic F127. Cryo-electron microscopy (cryo-EM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) demonstrate the existence of screw dislocation in the spiral assembled structure. The X-ray absorption fine structure spectrum indicates that Ru clusters are Ru³⁺ species, and Ru atoms are mainly coordinated with Cl with a coordination number of 6.5. Fourier-transform infrared (FT-IR) spectra and solid-state nuclear magnetic resonance hydrogen spectra (¹H NMR) indicate that the assembly process of Ru clusters is formed by noncovalent interactions, including hydrogen bonding and hydrophilic interactions. Additionally, the Ru-F127 CANs exhibit excellent photothermal conversion performance in the near-infrared (NIR) region.

Self-Assembled Surfactant-Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium-Ion Batteries

The mixing of [V10 O28 ]6- decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self-assembly of surfactant-templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge-like V2 O5 (gem-V2 O5 ). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V2 O5 consisting of very small crystallites (TBA-V2 O5 ). Electrochemical analysis of the materials' performance as lithium-ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long-range microstructure of the gem-V2 O5 cathode deliver higher initial capacity and superior capacity retention than TBA-V2 O5 . The smaller crystallite size and higher surface area of TBA-V2 O5 allow faster lithium insertion and superior rate performance to gem-V2 O5 .

Tunable Ordered Nanostructured Phases by Co-assembly of Amphiphilic Polyoxometalates and Pluronic Block Copolymers

The assembly of polyoxometalate (POM) metal-oxygen clusters into ordered nanostructures is attracting a growing interest for catalytic and sensing applications. However, assembly of ordered nanostructured POMs from solution can be impaired by aggregation, and the structural diversity is poorly understood. Here, we present a time-resolved small-angle X-ray scattering (SAXS) study of the co-assembly in aqueous solutions of amphiphilic organo-functionalized Wells-Dawson-type POMs with a Pluronic block copolymer over a wide concentration range in levitating droplets. SAXS analysis revealed the formation and subsequent transformation with increasing concentration of large vesicles, a lamellar phase, a mixture of two cubic phases that evolved into one dominating cubic phase, and eventually a hexagonal phase formed at concentrations above 110 mM. The structural versatility of co-assembled amphiphilic POMs and Pluronic block copolymers was supported by dissipative particle dynamics simulations and cryo-TEM.

Incorporating heterogeneous lacunary Keggin anions as efficient catalysts for solvent-free cyanosilylation of aldehydes and ketones

Polyoxometalates (POMs) as efficient catalysts can be used a wide range of chemical transformations due to their tunable Brønsted/Lewis-acidity and redox properties. Herein, we reported two hybrid and heterogeneous lacunary Keggin catalysts: (TBA)₇[PW₁₁O₃₉] (TBA-PW₁₁) and (TBA)₈[SiW₁₁O₃₉]·4H₂O (TBA-SiW₁₁) (TBA⁺: tetrabutylammonium) in which [XW₁₁O₃₉]ⁿ⁻ anions were coated by TBA⁺ cations. In this form, TBA⁺ can easily trap reactants on the surface of the catalysts and increase the catalytic reaction. Therefore, the catalytic performance of both POMs was tested in cyanosilylation of numerous compounds bearing-carbonyl group and trimethylsilyl cyanide under solvent-free conditions. TBA-PW₁₁ is more effective than TBA-SiW₁₁, conceivably due to the higher Lewis acidity of the P than the Si center and to the higher accessibility of the metal centers in the framework structure. Noteworthy, the recyclability and heterogeneity of both POMs catalysts were also examined, and the results confirmed that they remain active at least after three recycling procedures.

Layer-by-layer assembly of multilayered double hydroxides/polyoxometalate-coated magnetic nanoparticles for highly efficient phosphopeptide enrichment

A layer-by-layer (LbL) assembly strategy was developed to prepare multilayered double hydroxide/polyoxometalate shell-coated magnetic nanoparticles. The introduction of functional shells not only offered abundant affinity sites of metal oxide and metal ions but also increased the surface area for the contact with targets. By combining the enrichment strategies of immobilized metal ion affinity chromatography and metal oxide affinity chromatography, the nanomaterial can capture phosphopeptides via a synergistic effect. The method presented a low detection limit of 0.1 fmol in combination with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. The nanomaterial showed satisfactory selectivity (1:1:5000 M ratio of α-/β-casein/bovine serum albumin), good recovery (92.07%), high adsorption capacity (117.6 mg g^-1), and ten times reusability for capturing phosphopeptides.

Phosphomolybdic acid encapsulated in ZIF-8-based porous ionic liquids for reactive extraction desulfurization of fuels

Phosphomolybdic acid was encapsulated within a ZIF-8-based porous ionic liquid (HPMo@ZIF-8-PIL) for ultradeep reactive extraction desulfurization.

Amphiphilic Polyoxometalate-CNTs Nanohybrid as Highly Efficient Enzyme-free Electrocatalyst for H2O2 Sensing

Hybrid nanomaterials are emerging as a potential platform for the efficient detection of biomolecules, thus, the rational design of such materials has been widely explored. Polyoxometalates (POM) nanoclusters can serve...

Three Lanthanide-Functionalized Antimonotungstate Clusters with a {Sb4O4Ln3(H2O)8} Core: Syntheses, Structures, and Properties

Three lanthanide (Ln)-functionalized antimonotungstate (AT) clusters with a {Sb₄O₄Ln₃(H₂O)₈} core [H₂N(CH₃)₂]₁₄Na₈H₁₆[Sb₄O₄Ln₃(H₂O)₈W₂O₄(H₂O)₂(B-α-SbW₉O₃₃)₄]₂·87H₂O [Ln = Dy³⁺ (1), Ho³⁺ (2), Y³⁺ (3)] were synthesized in an acidic aqueous solution. Their molecular structural unit comprises two {Sb₄O₄Ln₃(H₂O)₈}-core-incorporated tetrameric [Sb₄O₄Ln₃(H₂O)₈W₂O₄(H₂O)₂ (B-α-SbW₉O₃₃)₄]^19- polyanionic units, each of which is assembled from an unprecedented [Sb₄O₄Ln₃(H₂O)₈W₂O₄(H₂O)₂]¹⁷⁺ heteroatom cluster surrounded by four trivacant [B-α-SbW₉O₃₃]^9- subunits. What is noteworthy is that a tetrahedral {Sb₄O₄} cluster is located at the center of the polyanionic unit, as far as we know, which is very infrequent in multi-Ln-functionalized polyoxometalate chemistry. Solid-state luminescent properties and energy migration of AT ligands to Dy³⁺ and Ho³⁺ cations in 1 and 2 have been intensively probed at ambient temperature. By varying the exciting wavelength from 250 to 450 nm, the emitting color could vary from blue to yellow for 1 and blue to green-yellow for 2, separately. In addition, high catalytic activities and good reusability of 2 as a heterogeneous catalyst for oxygenation reaction of sulfides have been systematically performed.

ZnO-POM Cluster Sub-1 nm Nanosheets as Robust Catalysts for the Oxidation of Thioethers at Room Temperature

Two-dimensional (2D) zinc oxides have attracted more and more research interests due to their unique properties. Yet, it remains a great challenge to limit the thickness to the sub-1 nm scale and further combine with other components to obtain 2D hybrid zinc oxide (ZnO)-based sub-1 nm materials. Herein, a versatile strategy was successfully developed to realize the controllable preparation of ZnO-polyoxometalate (POM)-based 2D hybrid sub-1 nm nanosheet (HSNS) superstructures by incorporating three kinds of molybdenum-based POM clusters into the zinc oxide system. Molecular dynamics simulation results demonstrated that POM clusters interact with ZnO/Zn(OH)₂ molecules and coassembled into stable 2D HSNSs. Significantly, theses materials as robust catalysts showed excellent catalytic activity, selectivity, and stability in the oxidation of thioethers at room temperature, which partly can be attributed to the special 2D sub-1 nm nanostructures with large specific areas leading to the full exposure of active sites. Meanwhile, the synergetic effect of multiple components also played an important role during the catalytic process. Thus, this work would pave the way for the precise synthesis of multicomponent 2D hybrid sub-1 nm materials for widespread applications.

Two unusual nanosized Nd3+-substituted selenotungstate aggregates simultaneously comprising lacunary Keggin and Dawson polyoxotungstate segments

Two unique nanosized Nd³⁺-substituted selenotungstates Na₉K₈{[W₃Nd₂(H₂O)₃(NO₃)O₆](B-α-SeW₉O₃₃)₂(α-Se₂W₁₄O₅₂)}·35H₂O (1) and [H₂N(CH₃)₂]₇H₉Na₄{[W₂Nd₂(H₂O)₈O₆(OH)₂(β-Se₂W₁₄O₅₂)][W₃Nd₂(H₂O)₆O₇(B-α-SeW₉O₃₃)₂]₂}·84H₂O (2) were prepared by reacting NaSeO₃, Na₂WO₄·2H₂O with Nd(NO₃)₃·6H₂O in aqueous solution by controlling different cations and pH values. 1 was synthesized at pH = 4.3 in the presence of KCl, whereas 2 was synthesized at pH = 3.0 in the presence of [H₂N(CH₃)₂]·Cl. The most striking structural feature of 1 and 2 is the coexistence of vacant Keggin and Dawson segments in the polyoxoanion, which is extremely rare in the field of polyoxometalate chemistry. The trimeric polyoxoanion of 1 can be perceived as a fusion of one α-type tetravacant Dawson [α-Se₂W₁₄O₅₂]^14- unit and two trivacant Keggin [B-α-SeW₉O₃₃]^8- segments sealing a trigonal bipyramid pentanuclear [W₃Nd₂(H₂O)₃(NO₃)O₆]¹¹⁺ cluster, while the pentameric polyoxoanion of 2 can be described as one β-type tetravacant Dawson [β-Se₂W₁₄O₅₂]^14- fragment and four trivacant Keggin [B-α-SeW₉O₃₃]^8- segments anchoring a saddle-shaped [W₈Nd₆(H₂O)₂₀O₂₀(OH)₂]²⁴⁺ cluster. In addition, the measurements of catalytic oxidation of aromatic thioethers show that 2 as a catalyst possesses extremely outstanding catalytic performance under mild reaction conditions.

Morphological transformation of ultrasonically obtained nanofibers during living self-assembly

The nanofibers are obtained by ionic self-assembly and living self-assembly.

SILCs in oxidative desulfurization: effect of support and heteropolyanion

Catalysts for oxidative desulfurization based on imidazolium ionic liquid and H₃PMo₁₂O₄₀ or H₃PW₁₂O₄₀, grafted to mesoporous silicas.

Two new isolated Zn-ε-Keggin clusters modified by conjugated organic ligands with decent electrocatalytic and third-order NLO properties

Compound 2 is the first isolated Zn₅PMo₁₂ cluster, and the two Zn-ε-Keggin-based compounds display excellent electrocatalytic and third-order NLO properties.

Cu(II) and magnetite nanoparticles decorated melamine-functionalized chitosan: A synergistic multifunctional catalyst for sustainable cascade oxidation of benzyl alcohols/Knoevenagel condensation

The uniform decoration of Cu(II) species and magnetic nanoparticles on the melamine-functionalized chitosan afforded a new supramolecular biopolymeric nanocomposite (Cs-Pr-Me-Cu(II)-Fe₃O₄). The morphology, structure, and catalytic activity of the Cs-Pr-Me-Cu(II)-Fe₃O₄ nanocomposite have been systematically investigated. It was found that Cs-Pr-Me-Cu(II)-Fe₃O₄ nanocomposite can smoothly promote environmentally benign oxidation of different benzyl alcohol derivatives by tert-butyl hydroperoxide (TBHP) to their corresponding benzaldehydes and subsequent Knoevenagel condensation with malononitrile, as a multifunctional catalyst. Interestingly, Fe₃O₄ nanoparticles enhance the catalytic activity of Cu(II) species. The corresponding benzylidenemalononitriles were formed in high to excellent yields at ambient pressure and temperature. The heterogeneous Cs-Pr-Me-Cu(II)-Fe₃O₄ catalyst was also very stable with almost no leaching of the Cu(II) species into the reaction medium and could be easily recovered by an external magnet. The recycled Cs-Pr-Me-Cu(II)-Fe₃O₄ was reused at least four times with slight loss of its activity. This is a successful example of the combination of chemo- and bio-drived materials catalysis for mimicing biocatalysis as well as sustainable and one pot multistep synthesis.

Self-Assembly of Ultrathin Nanocrystals to Multidimensional Superstructures

The self-assembly of ultrathin nanocrystals (UTNCs) into well-organized multidimensional superstructures is one of the key topics in material chemistry and physics. Highly ordered nanocrystal assemblies also known as superstructures or synthetic structures have remained a focus for researchers over the past few years due to synergy in their properties as compared to their components. Here, we aim to present the recent progress being made in this field with highlights of our research group endeavors in the engineering of self-assembled complex multidimensional superstructures of various inorganic materials, including polyoxometalates. The driving forces for the assembly process and its kinetics along with the potential applications associated with these unique ordered and spatially complex superstructures are also discussed.

Interaction among Worm-like Micelles in Polyoxometalate-Based Supramolecular Hydrogel

The co-assembly of zwitterionic amphiphile and polyoxometalate is a new and promising technique to construct a hierarchical and multifunctional supramolecular hydrogel. To comprehensively investigate the assemble mechanism, zwitterionic amphiphiles with different cations, namely, 3-(1-hexadecyl-3-imidazolio) propanesulfonate (C₁₆IPS) and 3-(1-hexadecyl-2-methyl-3-imidazolio) propanesulfonate (C₁₆bIPS), were designed to complex with silicotungstic acid (HSiW). Hydrogen bonding between the oxygen atoms of HSiW and the protons on C-2 of the imidazolium rings and the steric effect significantly influence the morphology and rheological property of the hydrogel. Interestingly, cross-linked worm-like micelles in parallel, vertical, and tilted distribution were observed using cryogenic transmission electron microscopy. In addition, these aggregates were further stacked into hexagonal phases on a large scale. Hence, deep insights into the relationship among the structure of zwitterionic amphiphile, self-assembled architecture, and the mechanical property of a polyoxometalate-based hydrogel were disclosed.

Topological Defect-Driven Buckling of Phospholipid Bicelles to Cones for Micromotors with Modulated Heading Pathways

Topological defects are crucial to the shaping of the crystalline membrane systems such as lipid bilayers, virus capsids, and graphene as well as the arrangement of cells in tissues. In a typical case, the introduction of disclination defects elastically buckles the crystalline membranes into conical shapes. However, how planar membranes transform to cones triggered by disclinations is still rarely observed in the experiments. Herein, we experimentally observe the transformation from phospholipid bicelles to cones in response to disclinations. During the transformation process, the wall thickness increases, while the conical generatrix length remains the same with respect to the radius of bicelles. The cones with apex angles of 112.8°, 83.6°, 60°, 39°, and 19.2° are observed when 1, 2, 3, 4, and 5 pentagon defects are introduced, respectively. Monodispersed microcones are obtained by adjusting aging temperature and time. These microcones are then used as templates to form platinum conical micromotors with open tips or closed tips, which display different heading directions in H₂O₂ solution. Our work provides a shape evolution pathway of planar membranes in response to disclinations. The homogeneous microcones can find wide applications in micromotors fabrication, the study of curvature-dependent processes, and the formation of advanced materials.

Guest Controlled Pillar[5]arene and Polyoxometalate Based Two-Dimensional Nanostructures toward Reversible Iodine Capture

The two-dimensional (2D) nanostructures comprised of polyoxometalate based building blocks are of great value in nanoarchitectures, which have unique properties and widespread potential applications, but it is still challenging in mature preparation. Herein a new strategy to build Cr(III) centered Anderson type polyoxometalate 2D nanostructures based on the modulation of host-guest interaction between cationic pillar[5]arenes and sodium dodecyl sulfonate (SDS) in aqueous media was exploited in this work. Through regulating stoichiometry of SDS, the morphology of assemblies vary from nanobones to 2D nanosheets. The fine assembled structure was discovered by combined ¹H NMR, SAXS, and element analyses. The nanomaterials can be used as adsorbents for I₂ in various solutions, including n-hexane, cyclohexane, water, and chloroform, where the polyoxometalates play a key role in the effective adsorption of iodine since they can expand the interspace between pillar[5]arenes in the as-prepared nanostructure. Furthermore, such adsorbents are easily regenerated and reused as iodine can be released spontaneously from nanobones@I₂ and nanosheets@I₂ solids when being immersed in dimethyl sulfoxide.

A hybrid material composed of a polyoxometalate of type BeW12O40 and an ionic liquid immobilized onto magnetic nanoparticles as a sorbent for the extraction of organophosphorus pesticides prior to their determination by gas chromatography

The authors describe a method for the extraction of organophosphorus pesticides (OPPs) by using a magnetically separable sorbent consisting of a polyoxometalate of type BeW₁₂O₄₀ supported on imidazole functionalized silica-coated cobalt ferrite. The sorbent was characterized by X-ray powder diffraction, field-emission scanning electron micrographs, vibrating sample magnetometry and FT-IR. The effects of the amount of adsorbent, pH value, salt concentration, extraction time, desorption solvent nature and volume and desorption time were investigated. Under optimal conditions, the method resulted in the following figures of merit: (a) the linear parts of the calibration plots typically extend from 0.08 to 300 μg mL^-1 of OPPs; (b) detection limits are between 0.02 to 0.06 ng mL^-1; and (c), extraction recoveries from spiked samples vary from 70.0 to 89.2%, with relative standard deviations between 5.4 and 7.6%. The nanocomposites can be reused up to 10 times. Compared to other methods for pretreatment and preconcentration of OPPs, the new method is more rapid, sensitive, accurate and eco-friendly. The method was successfully applied to the determination of the OPP residues in water samples and fruit juices. Graphical Abstract Schmatic presenation of the synthesis of core-shell magnetic nanoparticles (MNPs) of the type BeW12O40-ILSCCFNPs, and their application as sorbent for magnetic solid-phase extraction (MSPE) of organophosphorus pesticides.

Evolutionary Metal Oxide Clusters for Novel Applications: Toward High-Density Data Storage in Nonvolatile Memories

Because of current fabrication limitations, miniaturizing nonvolatile memory devices for managing the explosive increase in big data is challenging. Molecular memories constitute a promising candidate for next-generation memories because their properties can be readily modulated through chemical synthesis. Moreover, these memories can be fabricated through mild solution processing, which can be easily scaled up. Among the various materials, polyoxometalate (POM) molecules have attracted considerable attention for use as novel data-storage nodes for nonvolatile memories. Here, an overview of recent advances in the development of POMs for nonvolatile memories is presented. The general background knowledge of the structure and property diversity of POMs is also summarized. Finally, the challenges and perspectives in the application of POMs in memories are discussed.

Construction of Functionalized Annulated Sulfone via SO2/I Exchange of Cyclic Diaryliodonium Salts

A straightforward protocol for diarylannulated sulfone construction is efficiently established via SO₂/I exchange of iodonium(III) salts. Readily available inorganic Na₂S₂O₅ was served as a safe and convenient SO₂ surrogate. Diverse functionalized diarylannulated sulfones were smoothly achieved in good to excellent yields with great functional group compatibility. Organic light emitting diodes (OLEDs) material molecules were subsequently established via this method in gram scale. The unsymmetrical conjugated systems with donor-acceptor groups and π-conjugation bridges motifs, which substantially communicate electron mobility in semiconductor material molecules, were successfully afforded under the facile conditions of the exchange strategy.