Two Members of the {X4Nb16O56} Family (X = Ge, Si) Based on [(GeOH)2Ge2Nb16H2O54]12-and [K(GeOH)2Ge2Nb16H3O54]10-

Rocket-Shaped Telluroniobate with Efficient Catalytic Activity in the Transesterification Reaction

A novel telluroniobate, K₈Na₆H₇{[Co(en)₂(SO₃)][Te₄Nb₂₄O₇₉]}·42H₂O (en = ethylenediamine), has been synthesized through a diffusion strategy. It consists of a heteropolyoxoniobate [B-β-TeNb₉O₃₃]^17- cluster and isopolyoxoniobate {Nb₇O₂₂} building blocks. In addition, its structure was fully characterized by a series of spectroscopic methods. Furthermore, it exhibits an efficient catalytic performance in the transesterification of ethylene carbonate and methanol to prepare dimethyl carbonate with good catalytic reusability. Also, it demonstrates interesting proton conduction properties, with conductivity achieved at 3.05 × 10^-4 S cm^-1 (60 °C, 75% relative humidity).

A Three-Dimensional (3D) Indium-Containing Polyoxoniobate Framework Based on {In5Nb71}n Helical Pillars

A rare 3D Indium-containing polyoxoniobate framework {H₉[Cu(en)₂(H₂O)₂][Cu(en)₂]₁₂[In(en)]₅[Nb₂₃-O₆₅(OH)₃(H₂O)₂]{Nb₂₄O₆₇(OH)₂(H₂O)₃]₂}·68H₂O(1), based on the In-containing polyoxoniobate cluster, {[In(en)]₅[Nb₂₃O₆₅(OH)₃(H₂O)₂][Nb₂₄O₆₇(OH)₂(H₂O)₃]₂}^35- ({In₅Nb₇₁}) and [Cu(en)₂]²⁺ linkers has been successfully synthesized. The nest-like cluster {In₅Nb₇₁} is constructed from one brand-new V-shaped {Nb₂₃O₇₀}, two triangle-shaped {Nb₂₄O₇₂} and five [In(en)]³⁺. The [In(en)] fragments link {Nb₂₄O₇₂} and {Nb₂₃O₇₀} units into unique {In₅Nb₇₁}_n helical pillars. The copper-amine complexes connect the {In₅Nb₇₁}_n helical pillars into a three-dimensional (3D) inorganic-organic hybrid In-Cu-containing framework. This material also exhibits good ionic conductivity and vapor adsorption capacity properties.

An arsenicniobate-based 3D framework with selective adsorption and anion-exchange properties

An arsenicniobate-based cationic framework shows a high adsorption selectivity of water and ethanol and effectively removes toxic SCN⁻ anions.

Antimony-dependent expansion for the Keggin heteropolyniobate family

Antimony-dependent syntheses leading to the expansion of the Keggin heteropolyoxoniobate family involved nine new members.

Unprecedented high-nuclear transition-metal-cluster-substituted heteropolyoxoniobates: synthesis by {V8 } ring insertion into the POM matrix and antitumor activities

Reactions of hexaniobate with vanadate in the presence of Ni(2+) , Zn(2+) , or Cu(2+) have furnished three high-nuclear vanadium cluster-substituted heteropolyoxoniobates (HPNs): {Ni(en)3 }5 H{V(V) Nb8 V(IV) 8 O44 }⋅9 H2 O (1), (H2 en)Na2 [{Zn(en)2 (Hen)}{Zn(en)2 (H2 O)}2 {PNb8 V(IV) 8 O44 }]⋅11 H2 O (2), and Na{Cu(en)2 }3 {[Cu(en)2 ]2 [PNb8 V(IV) 8 O44 ]}⋅11 H2 O (3) (en=1,2-diaminoethane). Their structures have been determined and characterized by single-crystal X-ray diffraction analysis, thermogravimetric analysis (TGA), and elemental analysis. Structural analysis has revealed that compounds 1-3 contain similar {V8 }-substituted [X(V) Nb8 V(IV) 8 O44 ](11-) (X=P, V) clusters, obtained by inserting a {V8 } ring into tetravacant HPN [XNb8 O36 ](27-) . To the best of our knowledge, compounds 1-3 represent the first high-nuclear vanadium cluster-substituted HPNs, and compound 1 is the largest vanadoniobate cluster yet obtained in HPN chemistry. Nickel and zinc cations have been introduced into HPNs for the first time, which might promise a more diverse set of structures in this family. Antitumor studies have indicated that compounds 1 and 2 exhibit high activity against human gastric cancer SGC-7901 cells, SC-1680 cells, and MG-63 cells.