Organobor‐Funktionalisierung ermöglicht die hierarchische Aggregation gigantischer Polyoxometallat‐Nanokapseln

Two Giant Calixarene-Like Polyoxoniobate Nanocups {Cu12 Nb120 } and {Cd16 Nb128 } Built from Mixed Macrocyclic Cluster Motifs

Cup-shaped molecules are of great interest due to their appealing architectures and properties. Compared with widely studied calixarenes, polyoxometalate-based cup-shaped molecules currently remain a virgin land waiting for exploration. In this work, we report the first discovery of two giant cup-shaped inorganic-organic hybrid polyoxoniobates (PONbs) of {Cu₁₂ Nb₁₂₀ } and {Cd₁₆ Nb₁₂₈ }. The former integrates three tricyclic Nb₂₄ clusters and a hexacyclic Nb₄₈ cluster into a cup-shaped molecule via a Cu₁₂ metallacalixarene, while the latter unifies two tricyclic Nb₂₄ clusters and a brand-new pentacyclic Nb₄₀ cluster into another cup-shaped molecule via a hybrid Cd₁₆ unit. With 132 and 144 metal centers, {Cu₁₂ Nb₁₂₀ } and {Cd₁₆ Nb₁₂₈ } show the largest two inorganic-organic hybrid PONbs known to date.

High Proton-Conductivity in Covalently Linked Polyoxometalate-Organoboronic Acid-Polymers

The controlled bottom-up design of polymers with metal oxide backbones is a grand challenge in materials design, as it could give unique control over the resulting chemical properties. Herein, we report a 1D-organo-functionalized polyoxometalate polymer featuring a purely inorganic backbone. The polymer is self-assembled from two types of monomers, inorganic Wells-Dawson-type polyoxometalates, and aromatic organo-boronates. Their covalent linkage results in 1D polymer strands, which combine an inorganic oxide backbone (based on B-O and Nb-O linkages) with functional organic side-chains. The polymer shows high bulk proton conductivity of up to 1.59×10-1  S cm-1 at 90 °C and 98 % relative humidity. This synthetic approach could lead to a new class of organic-inorganic polymers where function can be designed by controlled tuning of the monomer units.

Multicomponent Self-Assembly of a Giant Heterometallic Polyoxotungstate Supercluster with Antitumor Activity

The hierarchical aggregation of molecular nanostructures from multiple components is a grand synthetic challenge, which requires highly selective linkage control. We demonstrate how two orthogonal linkage groups, that is, organotin and lanthanide cations, can be used to drive the aggregation of a giant molecular metal oxide superstructure. The title compound {[(Sn(CH3 )2 )2 O]4 {[CeW5 O18 ] [TeW4 O16 ][CeSn(CH3 )2 ]4 [TeW8 O31 ]4 }2 }46- (1 a) features dimensions of ca. 2.2×2.3×3.4 nm3 and a molecular weight of ca. 25 kDa. Structural analysis shows the hierarchical aggregation from several independent subunits. Initial biomedical tests show that 1 features an inhibitory effect on the proliferation of HeLa cells based on an apoptosis pathway. In vivo experiments in mice reveal the antiproliferative activity of 1 and open new paths for further development of this new compound class.