A Novel Hexatungstate Fragment Stabilized by Dimethyltin Groups: [{(CH3)2Sn}2(W6O22)]4-

Two isopolytungstate compounds based on rare [W6O22]8−and [H2W12O42]10−fragments captured by premade copper(ii) complexes

By utilizing the premade copper complexes two rare isopolytungstate [W₆O₂₂]⁸⁻and [H₂W₁₂O₄₂]¹⁰⁻based compounds were constructed under hydrothermal and ambient conditions, respectively.

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.

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.

Syntheses, structures and fluorescence properties of three rare-earth containing docosatungstates

Three rare-earth containing docosatungstates Na₃H₂[RE(H₂O)₄][RE(H₂O)₅]₂[W₂₂O₇₄H₂]·36H₂O [RE=Dy^III (1), Ho^III (2), Y^III (3)] have been synthesized by reaction of Na₂WO₄·2H₂O, dimethylamine hydrochloride (DMAHC) and RE(NO₃)₃·6H₂O in the aqueous solution and characterized by elemental analyses, IR spectra, thermogravimetric (TG) analysis, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1-3 are isomorphous and each molecular unit consists of a S-shaped docosatungstate [W₂₂O₇₄H₂]^14- polyoxoanion with two supporting [RE(H₂O)₅]³⁺ cations and one disordered [RE(H₂O)₄]³⁺ cation. The [W₂₂O₇₄H₂]^14- polyoxoanion can be viewed as combination of two hendecatungstate [W₁₁O₃₈H]^9- subunits in the staggered fashion by sharing two μ₂-O atoms. The TG curves of 1-3 reveal the one-step weight loss between 25°C to 700°C. Moreover, both 1 and 2 demonstrate the characteristic luminescence emission behaviors of the corresponding RE³⁺ ions and their lifetime decay curves can be well fitted to the double exponential function. In addition, the CIE chromaticity coordinates of 1 and 2 have been obtained based on their corresponding emission spectra, and their dominant wavelengths and color purities have been also calculated.

Organoantimony(III)-Containing Tungstoarsenates(III): From Controlled Assembly to Biological Activity

A family of three sandwich-type, phenylantimony(III)-containing tungstoarsenates(III), [(PhSb(III) ){Na(H2 O)}As(III) 2 W19 O67 (H2 O)](11-) (1), [(PhSb(III) )2 As(III) 2 W19 O67 (H2 O)](10-) (2), and [(PhSb(III) )3 (B-α-As(III) W9 O33 )2 ](12-) (3), have been synthesized by one-pot procedures and isolated as hydrated alkali metal salts, Cs3 K3.5 Na4.5 [(PhSb(III) ){Na(H2 O)}As(III) 2 W19 O67 (H2 O)]⋅41H2 O (CsKNa-1), Cs4.5 K5.5 [(PhSb(III) )2 As(III) 2 W19 O67 (H2 O)]⋅35H2 O (CsK-2), and Cs4.5 Na7.5 [(PhSb(III) )3 (B-α-As(III) W9 O33 )2 ]⋅42H2 O (CsNa-3). The number of incorporated {PhSb(III) } units could be selectively tuned from one to three by careful control of the reaction parameters. The three compounds were characterized in the solid state by single-crystal XRD, IR spectroscopy, and thermogravimetric analysis. The aqueous solution stability of sandwich polyanions 1-3 was also studied by multinuclear ((1) H, (13) C, (183) W) NMR spectroscopy. Effective inhibitory activity against six different kinds of bacteria was identified for all three polyanions, for which the activity increased with the number of incorporated {PhSb(III) } groups.

What can electrospray mass spectrometry of paratungstates in an equilibrating mixture tell us?

[W₇O₂₄]⁶⁻, the main species in an aqueous solution of Na₂WO₄at pH ≤ 7 proved by NMR and Raman spectroscopy, fails to be detected in ESI-MS due to its ESI-induced dissociation into Lindqvist [W₆O₁₉]²⁻.

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.

Synthesis and biological activity of organoantimony(III)-containing heteropolytungstates

Three discrete organoantimony(III)-containing heteropolytungstates [(PhSb(III))(4)(A-α-Ge(IV)W(9)O(34))(2)](12-) (1), [(PhSb(III))(4)(A-α-P(V)W(9)O(34))(2)](10-) (2), and [{2-(Me(2)NCH(2)C(6)H(4))Sb(III)}(3)(B-α-As(III)W(9)O(33))](3-) (3) have been synthesized in one-pot reactions in aqueous medium using the appropriate lacunary heteropolyanion precursor and organoantimony(III) source. Polyanions 1-3 were isolated as hydrated salts, (NH(4))(12)[(PhSb(III))(4)(A-α-Ge(IV)W(9)O(34))(2)]·20H(2)O (1a), Rb(9)Na[(PhSb(III))(4)(A-α-P(V)W(9)O(34))(2)]·20H(2)O (2a), and Rb(3)[{2-(Me(2)NCH(2)C(6)H(4))Sb(III)}(3)(B-α-As(III)W(9)O(33))]·7H(2)O (3a). The compounds 1a-3a were fully characterized in the solid state using infrared (IR) spectroscopy, single-crystal XRD, and thermogravimetric and elemental analyses. The stability of 1-3 in aqueous solution was confirmed by multinuclear NMR ((1)H, (13)C, (31)P, and (183)W) spectroscopy. Preliminary studies on the biological activity of 1-3 showed that all three compounds might act as potent antimicrobial agents.

A General Strategy for Ligation of Organic and Biological Molecules to Dawson and Keggin Polyoxotungstates

The copper-catalyzed azide/alkyne cycloaddition (click chemistry) is used for the first time in polyoxometalate chemistry to graft any kind of organics (lipophilic, water-soluble, biologically relevant) to polyoxotungstates to generate hybrids. The method is not limited by solvent matching between the polyoxometallic platforms and the organic substrates.

13-Tungstoborate Stabilized by an Organostannoxane Hexamer

The novel dimethyltin-containing polyanion [{(CH3)2Sn}6(OH)2O2(H2BW13O46)2]12- (1) is composed of two [H2BW13O46]9- clusters linked by an unprecedented planar, hexameric [{(CH3)2Sn}6(OH)2O2]8+ organostannoxane moiety, representing the first X-ray structural characterization of a molecular hybrid organic-inorganic tungstoborate and of the elusive [HnBW13O46](11-n)- species.