A Zr-added Dawson-type poly(polyoxometalate)

A novel Zr-added trimer, [H₂N(CH₃)₂]₁₀H₁₄[(Zr₂P₂W₁₆O₆₁)₃]·7H₂O (1), has been made under hydrothermal conditions, and contains the highest number of Zr centers in known Dawson-type poly(POM)s. A remarkable feature of this study is the first discovery of a new type of divacant [α-5,10-P₂W₁₆O₆₀]^14- fragment, which assembles with Zr⁴⁺ ions to form a cyclic trimer. Furthermore, 1 as a heterogeneous catalyst exhibits high activity for the selective oxidative degradation of a sulfur mustard simulant CEES.

Synthesis, Structure, and Catalytic Activities of Two Multi-Rh-Decorated Polyoxometalates

Two multi-Rh-incorporated polyoxometalates [NH₂(CH₃)₂]₁₀[Na₄(H₂O)₈]H₃[As₄W₄₂O₁₄₂(OH)₄(CH₃COO)₂Rh₃(H₂O)₄]·13H₂O·4[NH(CH₃)₂] (1) and [K₄Na(H₂O)₆]KH₁₀[As₄W₄₀O₁₄₀Rh₄(H₂O)₄]·34H₂O (2) have been synthesized in acetate buffer solution. Polyanion 1a is built up atop of an acetate-modified rectangular framework [As₄W₄₂O₁₄₂(OH)₄(CH₃COO)₂]^26-, while polyanion 2a contains a pure inorganic cryptand [As₄W₄₀O₁₄₀]^28-. All Rh atoms of these two compounds share the same hexa-coordinate distorted-octahedral geometry and are embedded into their cavities through As-Rh bonding with a bond length around 2.304(4)-2.436(5) Å. Besides, they not only represent structural novelty but also demonstrate controllable proton conduction properties. Catalysts 1 and 2 can catalyze cycloaddition of epoxides with CO₂ in a solvent-free system in conjunction with 1-ethyl-1-methylpyrrolidinium bromide.

{Ti6}/{Ti10} Wheel Cluster Substituted Silicotungstate Aggregates

Two novel Ti-oxo wheel cluster substituted silicotungstates (STs) [H₂N(CH₃)₂]₉H₉[Ti₆O₆(SiW₁₀O₃₇)₃]·11H₂O (1) and [H₂N(CH₃)₂]₁₆H₁₀[Ti₁₀O₁₁(SiW₁₀O₃₇)₂(SiW₉O₃₅)₂]·14H₂O (2) have been made by hydrothermal reactions. The polyoxoanion of 1 is a ring-shaped trimer where a Ti₆O₆ ({Ti₆}) wheel cluster is encapsulated by three divacant [SiW₁₀O₃₇]^10- (SiW₁₀O₃₇) fragments. However, 2 is built by two divacant SiW₁₀O₃₇ units and two rare trivacant [SiW₉O₃₅]^12- (SiW₉O₃₅) fragments and further installs an unprecedented Ti₁₀O₁₁ ({Ti₁₀}) double-wheel cluster. To the best of our knowledge, 2 is rare in POM chemistry. Studies on the catalytic oxidation properties reveal that 1 exhibits high catalytic activity toward the oxidation of various sulfides using H₂O₂ as an oxidant. Furthermore, 1 can be facilely recycled and reused for at least five cycles without obvious loss of catalytic activity.

Fascinating interlocked triacontanuclear giant nanocages

We report herein three air, thermal and solvent stable interlocked triacontanuclear giant nanocages, generated using a node and spacer concept. Interestingly, the crystal structures of the cages are not only nano-dimensional but also exist in the nano-dimension range, which was corroborated with microscopic images. The combination of microscopic and crystallographic data, in effect, led us to a unique advantageous situation of generating nanomaterials with hard-to-come-by structural information at the molecular level.

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.

Preparations, Structures and Luminescence Properties of Penta-rare-earth Incorporated Tetravacant Dawson Selenotungstates and Their Ho3+ /Tm3+ Co-doped Derivatives

A family of penta-rare-earth incorporated tetravacant Dawson selenotungstates [H₂ N(CH₃ )₂ ]₁₀ H₃ [SeO₄ RE₅ (H₂ O)₇ (Se₂ W₁₄ O₅₂ )₂ ] ⋅ 40H₂ O [RE=Ho³⁺ (1), Er³⁺ (2), Tm³⁺ (3), Tb³⁺ (4)] were synthesized. It should be noted that a penta-RE [SeO₄ RE₅ (H₂ O)₇ ]¹¹⁺ central core connecting two tetra-vacant Dawson-type [Se₂ W₁₄ O₅₂ ]^12- subunits generates a dimeric assembly of [SeO₄ RE₅ (H₂ O)₇ (Se₂ W₁₄ O₅₂ )₂ ]^13- in the structures of 1-4. Meanwhile, a class of Ho³⁺ /Tm³⁺ co-doped derivatives based on 1 with a Ho³⁺ /Tm³⁺ molar ratio of 0.75:0.25-0.25:0.75 were also prepared and characterized by energy-dispersive spectroscopy (EDS) analyses. Moreover, their luminescence properties were systematically investigated, which indicate that Tm³⁺ ions can sensitize the emission of Ho³⁺ ions in the visible region and prolong the fluorescence lifetime of Ho³⁺ ions to some extent. Energy transfer from Tm³⁺ ions to Ho³⁺ ions was probed by time-resolved emission spectroscopy (TRES), and the CIE 1931 diagram has been applied to evaluate all possible luminescence colors.

First series of mixed (PIII, SeIV)-heteroatomoriented rare-earth-embedded polyoxotungstates containing distinct building blocks

A series of unprecedented mixed heteroatoms-oriented rare-earth-embedded heteropolyoxotungstates 1–8 were prepared and the 1@CMWCNT-GCE electrochemical sensing performances toward DA and UA were studied.

Copper(ii)-containing tungstotellurates(vi): syntheses, structures and their catalytic performances in selective oxidation of thioethers

We report the syntheses and structures of two new copper(ii)-containing tungstotellurates(vi) Na₁₂[Te^VI₂W₈O₃₈Cu₂(H₂O)₂]·7H₂O (Te₂W₈Cu₂) and Na₆[Te^VIW₆O₂₄Cu(NH₂CH₂CO₂)₂]·6H₂O (TeW₆Cu). The two compounds were synthesized by a simple one-pot method and characterized by single-crystal X-ray diffraction (XRD), powder XRD, FT-IR spectroscopy, elemental analysis, and thermogravimetric analysis in the solid state. Furthermore, their catalytic properties for the selective oxidation of thioethers were also studied systematically. The catalytic experiment results indicate that the tungstotellurate(vi) Te₂W₈Cu₂ is an effective heterogeneous catalyst for the selective oxidation of thioethers to sulfoxides or sulfones by an H₂O₂ oxidant at room temperature. Under the ambient conditions, Te₂W₈Cu₂ can convert 99% of methyl(phenyl)sulfane to sulfoxides or sulfones with 96% or 99% selectivity, respectively, and the utilization rate of H₂O₂ is up to 80%. Furthermore, Te₂W₈Cu₂ as a heterogeneous catalyst is stable in the reaction and could be reused at least five cycles with conserved activity.

Two copper(ii)-containing tungstotellurates(vi) were synthesized and present very high catalytic activity for the selective oxidation of thioethers under ambient conditions.

Pathways towards true catalysts: computational modelling and structural transformations of Zn-polyoxotungstates

Current catalysis undergoes a paradigm shift from molecular and heterogeneous realms towards new dynamic catalyst concepts. This calls for innovative strategies to understand the essential catalytic motifs and true catalysts emerging from oxidative transformation processes. Polyoxometalate (POM) clusters offer an inexhaustible reservoir for new noble metal-free catalysts and excellent model systems whose structure-activity relationships and mechanisms remain to be explored. Here, we first introduce a new {Zn_nNa_6-n(B-α-SbW₉O₃₃)₂} (n = 3-6) catalyst family with remarkable tuning options of the Zn-based core structure and high activity in H₂O₂-assisted catalytic alcohol oxidation as a representative reaction. Next, high level solution-based computational modelling of the intermediates and transition states was carried out for [Zn₆Cl₆(SbW₉O₃₃)₂]^12- as a representative well-defined case. The results indicate a radical-based oxidation process with the involvement of tungsten and adjacent zinc metal centers. The {Zn_nNa_6-n(B-α-SbW₉O₃₃)₂} series indeed efficiently catalyses alcohol oxidation via peroxotungstate intermediates, in agreement with strong spectroscopic support and other experimental evidence for the radical mechanism. Finally, the high performance of [Zn₆Cl₆(SbW₉O₃₃)₂]^12- was traced back to its transformation into a highly active and robust disordered Zn/W-POM catalyst. The atomic short-range structure of this resting pre-catalyst was elucidated by RMC modelling of the experimental W-L₃ and Zn-K edge EXAFS spectra and supported with further analytical methods. We demonstrate that computational identification of the reactive sites combined with the analytical tracking of their dynamic transformations provides essential input to expedite cluster-based molecular catalyst design.

Self-Assembly of Nanoscale Lanthanoid-Containing Selenotungstates: Synthesis, Structures, and Magnetic Studies

The reaction of mid-lanthanide (Ln) ions with the preformed {Se₆W₃₉} precursor under reasonably acidic aqueous conditions in the presence of organic amine cations results in an unprecedented nanoscale lanthanide-functionalized polyoxotungstate family, which are rare examples of mid-lanthanide-containing selenotungstates. (C₄H₁₀NO)₉Na₃[Dy₃Se_3.5W₃₀O_107.5(H₂O)₁₀]·22H₂O (1) and (NH₄)₃(C₂H₈N)Na₂[Dy₄Se₆W₃₈O₁₃₂(H₂O)₂₆(OH)₆]·18H₂O (2) reveal a trimeric Keggin assembly and a cyclic {Se₆W₃₈}-based chain, respectively, whereas (NH₄)₄Na₈[Gd₄Se₆W₄₈O₁₆₆(H₂O)₂₀(OH)₄]·21H₂O (3) and (NH₄)₉(C₂H₈N)₄Na₅[Ln₆Se₆W₅₈O₂₀₂(H₂O)₂₀(OH)₄]·58H₂O (4; Ln = Gd, Tb, or Dy) are a few examples of polyoxometalates consisting of both classical Keggin and Wells-Dawson building blocks, and (NH₄)₄(C₂H₈N)₅Na₁₃[Ln₄Se₈W₅₆O₁₉₆(H₂O)_x(OH)₁₀]·40H₂O (5; Ln = Gd, Tb, or Dy; x = 12 for Gd and Tb and 10 for Dy) features the largest "pure" Wells-Dawson selenotungstate {Se₈W₅₆} bearing a length of 3.73 nm. A library of Se-templated species involving the first reported Keggin {α-SeW₈} and Wells-Dawson {α-Se₂W₁₆} building blocks as well as some decisive assembly factors during the synthesis is responsible for these architectures. All of the compounds were structurally characterized in the solid and solution by single-crystal X-ray diffraction, IR, thermogravimetric-differential thermal analysis, and electrospray ionization mass spectrometry. Magnetic properties indicate that 1 and 4-Dy show probable single-molecule-magnet behavior with obvious frequency dependence, whereas 3 and 4-Gd present the antiferromagnetic interactions between the Gd^III centers.

Blurring the line between addenda and heteroatoms in a giant polyoxotungstotellurite

The 3.5 nm-sized polyanion [H₄TeWO₃₇₂]^80-, exhibiting an exceptionally high Te : W ratio, expands the structural role of Te^IV ions from classical heterogroups within polyoxotungstate subunits to addenda ions. Investigations on the self-assembly conditions, proceeding in a simple one-pot reaction, point to the pH as one critical factor for circumventing this limitation.

1-D Chain Tungstotellurate Hybrids Constructed from Organic-Ligand-Connecting Iron-Lanthanide Heterometal Encapsulated Tetrameric Polyoxotungstate Units

A family of inorganic-organic hybrid one-dimensional (1-D) chain iron-lanthanide (Ln) heterometal encapsulated tungstotellurates [H₂N(CH₃)₂]₈K₂Na₄[Ln₂(Ac)₂(H₂O)₄Fe₂(Hpdca)₂(B-β-TeW₉O₃₃)₂][Ln₂(H₂O)₈Fe₂(Hpdca)₂(B-β-TeW₉O₃₃)₂]·50H₂O [Ln = Eu³⁺ (1), Tb³⁺ (2), Dy³⁺ (3), Er³⁺ (4), HAc = acetate acid, H₂pdca = 2,5-pyridinedicarboxylic acid] were prepared using a facile "one-pot" reaction. The molecular structures of 1-4 consist of an intriguing organic-ligand-connecting Fe-Ln heterometal inserted tetrameric unit [Ln₂(Ac)₂(H₂O)₄Fe₂(Hpdca)₂(B-β-TeW₉O₃₃)₂][Ln₂(H₂O)₈Fe₂(Hpdca)₂(B-β-TeW₉O₃₃)₂]^14-. Appealingly, the tetrameric unit is composed of two sandwich-type subunits [Ln₂(Ac)₂(H₂O)₄Fe₂(Hpdca)₂(B-β-TeW₉O₃₃)₂]^8- and [Ln₂(H₂O)₈Fe₂(Hpdca)₂(B-β-TeW₉O₃₃)₂]^6-, in which each sandwich-type subunit can be regarded as a derivative of two Ln-organic complexes substituting two external Fe^III ions in the classic Krebs-type [Fe₄(H₂O)₁₀(β-TeW₉O₃₃)₂]^4- fragment. Furthermore, adjacent tetrameric units are interconnected into a 1-D chain arrangement by Hpdca^- bridges. 1-4 represent the first examples of Fe-Ln heterometal encapsulated tungstotellurates. Comprehensive magnetic measurements of 3 imply the possible single-molecule magnet properties in 3 with an estimated relaxation time τ₀ ≈ 6.06 × 10^-6 s at H_dc = 0 Oe and τ₀ ≈ 6.97 × 10^-5 s at H_dc = 1500 Oe. In addition, the solid-state photoluminescence spectra of 1 and 2 at room temperature exhibit the typical f-f transitions of Ln cations. The Commission International d'Eclairage (CIE) color coordinates of (0.540 24, 0.442 44) for 1 and (0.428 71, 0.428 30) for 2 along with the correlated color temperatures of 1995 and 3278 K, dominant wavelengths of 586 and 578 nm, and color purities of 95.09% and 57.27% for 1 and 2 are obtained.

Recent advances in isopolyoxotungstates and their derivatives

During the past decade, isopolyoxotungstates (iso-POTs) and their derivatives have been greatly developed due to their unique structures and potential applications in luminescence, magnetism, catalysis etc. This brief review is principally focused on the main research progress on iso-POTs, iso-POT-based transition-metal derivatives, iso-POT-based rare-earth derivatives, iso-POT-based organometallic derivatives and iso-POT-based heterometallic derivatives, and gives a summary of some representative examples of their syntheses, structures and related properties. In addition, an outlook on the future of this area is presented in the final section. We believe that this systematic commentary on iso-POTs and their derivatives will not only disclose a rich set of iso-POT structures, but also reveal a more promising direction for the further functionalization of iso-POTs.

First Dimethyltin-Functionalized Rare-Earth Incorporated Tellurotungstates Consisting of {B-α-TeW7O28} and {W5O18} Mixed Building Units

The facile one-step assembly reaction of Na₂WO₄·2H₂O, Sn(CH₃)₂Cl₂, RE(NO₃)₃·6H₂O and K₂TeO₃ in the presence of dimethylamine hydrochloride as an organic solubilizing agent in acidic aqueous solution resulted in a family of dimethyltin-functionalized rare-earth (RE) incorporated tellurotungstates consisting of {B-α-TeW₇O₂₈} and {W₅O₁₈} mixed building units [H₂N(CH₃)₂]₈Na₄H₂[RE₂(OH)(B-α-TeW₇O₂₈)Sn₂(CH₃)₄(W₅O₁₈)]₂·18H₂O [RE = Er^III (1), Yb^III (2), Ho^III (3), Y^III (4)]. The most striking structural characteristic of 1-4 is that they all contain a novel tetrameric S-shaped [RE₂(OH)(B-α-TeW₇O₂₈)Sn₂(CH₃)₄(W₅O₁₈)]₂^14- moiety simultaneously including two pentavacant Keggin [B-α-TeW₇O₂₈]^12- and two monovacant Lindqvist [W₅O₁₈]^6- fragments connected by RE and dimethyltin linkers. To the best of our knowledge, such dimethyltin-functionalized RE-containing tellurotungstates have not been reported before. The visible or NIR solid-state emission spectra of 1 and 3 display the characteristic emission bands arising from Er^III and Ho^III centers. Moreover, various 1-Er/Yb co-doped samples were prepared by controlling different mass ratio of Er(NO₃)₃·6H₂O/Yb(NO₃)·6H₂O in the range of 0.96:0.04-0.02:0.98. In the visible region, the emission intensity of the 1-Er_0.40/Yb_0.60 co-doped sample reaches the maximum at the mass ratio of Er(NO₃)₃·6H₂O/Yb(NO₃)·6H₂O being 0.40:0.60, and this observation is mainly derived from the fact that the Yb³⁺ ions can sensitize the Er³⁺ ions to enhance the emission intensity in the visible region. However, no such phenomenon for the 1-Er/Yb co-doped samples is seen in the NIR region. Besides, the upconversion spectra of the 1-Er/Yb co-doped samples were first observed. In addition, the thermal stabilities of 1-4 were also investigated on the crystalline samples and the thermal decomposition process of 1 has been deeply studied.

Discovery and Evolution of Polyoxopalladates

Noble metal catalysts, in particular palladium-containing materials, are of prime commercial interest, because of their role as oxidation catalysts in automobile emission-control systems and reforming catalysts for the production of high-octane gasoline. However, despite almost two centuries of research, the precise structure of such materials is still ill-defined on the sub-nanometer scale, which severely limits the understanding of the underlying catalytic mechanisms. As a burgeoning class of structurally well-defined noble metal oxide nanoclusters, polyoxopalladates (POPs) have been highly rated as ideal models to fully decipher the molecular mechanism of noble metal-based catalysis. Being at the frontier of polyoxometalates (POMs), the chemistry of POPs, which are based exclusively on Pd^II centers as addenda is currently progressing rapidly, owing to their structural and compositional novelty, high solution stability, combined with promising applications especially as noble metal-based catalysts. Controlled hydrolysis-condensation processes of square-planar Pd^IIO₄ units in the presence of external oxyacid heterogroups (e.g., AsO₄^3-, PO₄^3-, and SeO₃^2-) drive the self-assembly of such discrete, polynuclear Pd^II-oxo nanoclusters in facile one-pot reactions using aqueous solvents. By now, more than 70 POPs have been discovered, encompassing a large structural variety, including cube, star, bowl, dumbbell, wheel, and open-shell archetypes. Moreover, the POP cages can serve as adaptable molecular containers for encapsulation/interaction with a range of metallic elements across the s, p, d, and f blocks of the periodic table, resulting in a library of host-guest assemblies of varying shapes and sizes. Besides a delicate balance of experimental variables, the fine-tuning of POP structure, composition, and properties is possible by systematic replacement of the metal ion guest and/or the capping heterogroups. Besides, nearly all POPs obtained so far could be perfectly rationalized by theoretical calculations, and even prediction of the design and synthesis of new POP structures is possible. The excellent stability of POPs in the solid state and in solution (both aqueous and organic media) and gas phase allows for applications mainly in homo- and heterogeneous catalysis or as molecular precursors for monodisperse nanoparticles via an ingenious bottom-up route for functional nanotechnology. Apart from catalysis, owing to the unique structural features of POPs, other areas of interest exist, for example, in magnetism as molecular spin qubits and in biology as aqueous-phase macromolecular models. Overall, as a distinct subclass of POMs, POPs not only integrate the advantages of tunable shape, size, composition, solution stability, redox activity, and facile synthetic procedures, but drive immense potential for achieving an atom-to-atom fabrication and modulation of nanostructures as well, thereby providing models for unveiling mechanistic insight of noble metal-based catalysis at the molecular level, which will, in turn, guide the programmed assembly of nanomaterials with improved performance in a controllable manner. This Account is directed to cover the main structural types of POPs and to discuss the structure-directing template effects induced by the guest ions on the resultant host-guest assemblies.

A high-nuclearity isopolyoxotungstate based manganese cluster: one-pot synthesis and step-by-step assembly

A manganese(iii,iv)-tungsten(vi) supercluster based on 72 manganese ions (48 MnIV and 24 MnIII) and 48 tungsten(vi) centers [{MnIV24MnIII12O28(H2O)23}2(W24O120)2]40- has been prepared from the carboxylic Mn12 cluster. Its structure comprises two unprecedented cage-like Mn36W24 cores linked via two Mn-O-W bonds, leading to a Mn72W48 assembly. The inorganic synthetic mechanism was investigated through different synthesis methods and comprehensive ESI-MS tests.

Rare-Earth-Incorporated Tellurotungstate Hybrids Functionalized by 2-Picolinic Acid Ligands: Syntheses, Structures, and Properties

A series of organic-inorganic rare-earth-incorporated tellurotungstate hybrids, Na₄[RE₂(H₂O)₄(pica)₂W₂O₅][(RE(H₂O)W₂(Hpica)₂O₄)(B-β-TeW₈O₃₀H₂)₂]₂·38H₂O (RE = La^III (1), Ce^III (2), Nd^III (3), Sm^III (4), Eu^III (5); Hpica = 2-picolinic acid), were prepared via a one-step assembly reaction of Na₂WO₄·2H₂O, RE(NO₃)₃·6H₂O, K₂TeO₃, Hpica, and triethylamine (tea). Notably, the solubilization of tea toward Hpica and the solubilization of Hpica toward RE cations in the reaction system play an important role in the formation of 1-5. The most significant feature of 1-5 consists of an intriguing tetrameric [RE₂(H₂O)₄(pica)₂W₂O₅][(RE(H₂O)W₂(Hpica)₂O₄)(B-β-TeW₈O₃₀H₂)₂]₂^4- polyoxoanion constructed from two tetravacant Keggin sandwich-type [(RE(H₂O)W₂(Hpica)₂O₄)(B-β-TeW₈O₃₀H₂)₂]^5- entities linked by a RE-W-Hpica {RE₂(H₂O)₄(pica)₂W₂O₅}⁶⁺ cluster, in which Hpica ligands not only play a key bridging role in linking RE and W centers by carboxylic groups in an irregular N-O-RE-O-W-O six-membered-ring motif but also can directly chelate with W centers via N and O atoms in a stable N-O-C-O-W five-membered-ring fashion. 1-5 represent rare organic-inorganic hybrid RE-substituted tellurotungstates. Moreover, the solid-state photoluminescence properties of 3-5 have been deeply investigated, and these compounds exhibit the characteristic emission stemming from intra-4f transitions of RE ions. The energy transfer of the O → W transitions sensitizing the emission of Sm^III centers in 4 is convincingly proved by time-resolved emission spectra (TRES); the increase in the strongest typical emission of Sm^III ions at a decay time of 17 μs is accompanied by the decline of O → W emission, and the CIE 1931 diagram was obtained from the corresponding TRES. Furthermore, a comparison of the luminescence behaviors of 5 in the solid state and in solution reveals the structural skeletal integrity of 5 in solution and a shorter decay lifetime in the solution caused by the high-frequency O-H oscillators.

pH-Controlled One Pot Syntheses of Giant Mo2O2S2-Containing Seleno-Tungstate Architectures

Self-assembly reactions of Na₂WO₄, SeO₂/SeO₃^2-, and [Mo₂O₂(μ-S)₂(H₂O)₆]²⁺ give, depending on the pH value, two new large polyoxometalate complexes: i.e., [(γ-Se₂W₁₄O₅₂)₃(Mo₂O₂(μ-S)₂(H₂O)₂)₆]^24- (1) isolated at pH 3.5 and [(γ-Se₂W₁₄O₅₂)₄(WO₃(H₂O))₈(W₂O₅)₂(W₄O₁₂)₂(Mo₂O₂(μ-S)₂(H₂O)₂)₄(Mo₂O₂(μ-S)₂(SeO₃))₄]^36- (2) isolated at pH 2. Both compounds were characterized in the solid state by single-crystal X-ray diffraction, EDX, elemental analysis, TGA, and FT-IR and in solution by ESI-MS and NMR.

Dimethyltin-functionalized cyclic selenotungstates based on {Se2W12} units

Two dimethyltin-functionalized cyclic selenotungstates based on {Se₂W₁₂} units were obtained, where (CH₃)₂Sn²⁺ moieties were first introduced into “pure” POMs wheels.

Tellurotungstate-Based Organotin-Rare-Earth Heterometallic Hybrids with Four Organic Components

A family of unprecedented tellurotungstate-based organotin-rare-earth (RE) heterometallic hybrids [H₂N(CH₃)₂]₆H₁₂Na₂ {[Sn(CH₃)W₂O₄(IN)][(B-α-TeW₈O₃₁)RE(H₂O) (Ac)]₂}₂·25H₂O [RE = Ce^III (1), Pr^III (2), Nd^III (3), Sm^III (4), Eu^III (5), Gd^III (6), Tb^III (7); HIN = isonicotinic acid, HAc = acetic acid] were synthesized and characterized by elemental analyses, IR spectra, UV spectra, thermogravimetric analyses, powder X-ray diffraction, and single-crystal X-ray diffraction. The polyoxoanionic skeletons {[Sn(CH₃)W₂O₄(IN)][(B-α-TeW₈O₃₁)RE(H₂O) (Ac)]₂}₂^20- of 1-7 are constructed from two symmetrical units {[Sn(CH₃)W₂O₄(IN)][(B-α-TeW₈O₃₁)RE(H₂O) (Ac)]₂}^10- linked by two acetate connectors, which not only represent the first inorganic-organic hybrid RE-substituted tellurotungstates involving three different organic ligands, but also stand for the first samples of organotin-RE heterometallic polyoxometalate derivatives. The solid-state luminescent emission properties of 2-5 mainly display the characteristic emission bands of RE^III cations, whereas during the emission procedure of 7, [B-α-TeW₈O₃₁]^10- segments make a nonignorable contribution to the PL behavior of 7 accompanying by the occurrence of the intramolecular energy transfer from O→W LMCT energy to Tb³⁺ centers. Furthermore, 4@CTAB composites with peanutlike and honeycombed morphologies were prepared by a surfactant cetyltrimethylammonium bromide (CTAB). The time-resolved emission spectra of the 4@CTAB composite with CTAB/4 = 0.033/0.05 consolidate the energy transfer from CTAB to RE^III centers. Variable-temperature magnetic susceptibility measurements for 2, 3, and 4 were performed.

Classical/Non-classical Polyoxometalate Hybrids

Two polyanions [Se^I V₂ Pd^II₄ W^VI₁₄ O₅₆ H]^11- and [Se^I V₄ Pd^II₄ W^VI₂₈ O₁₀₈ H₁₂ ]^12- are the first hybrid polyoxometalates in which classical (Group 5/6 metal based) and non-classical (late transition-metal based) polyoxometalate units are joined. Requiring no supporting groups, this co-condensation of polyoxotungstate and isopolyoxopalladate constituents also provides a logical link between POM-Pd^II coordination complexes and the young subclass of polyoxopalladates. Solid-state, solution, and gas-phase studies suggest interesting specific reactivities for these hybrids and point to several potential derivatives and functionalization strategies.

Rearrangement of {α-P2W15} to {PW6} moieties during the assembly of transition-metal-linked polyoxometalate clusters

Formation of a series of polyoxometalates showing the unprecedented transformation of a Dawson lacunae into a Keggin lacunae.

The main progress over the past decade and future outlook on high-nuclear transition-metal substituted polyoxotungstates: from synthetic strategies, structural features to functional properties

In this article, we discuss the synthetic methodologies, structural diversities and relevant properties of the high-nuclear TMSPTs reported in the past decade.

Two new members of the niobium-substituted polytungstophosphate family based on hexalacunary [H2P2W12O48]12− building blocks

Herein we present two structurally novel nanoscale clusters [{Nb₆(O₂)₄P₂W₁₂O₅₇}₂]²⁰⁻ (1) and [{P₂W₁₂Nb₇O₆₃(H₂O)₂}₄{Nb₄O₄(OH)₆}]³⁰⁻ (2) formed by controlling the reaction parameters.

Assembly of tetrameric dimethyltin-functionalized selenotungstates: from nanoclusters to one-dimensional chains

The first dimethyltin-functionalized selenotungstates have been isolated: nanocluster {Sn₇Se₈W₅₄} exhibiting photocatalytic H₂ evolution activity and chain {Sn₁₆Se₁₁W₅₆} contain {β-Se₂W₁₅} and {γ-Se₂W₁₄} building blocks, respectively.