Giant Polyoxoniobate‐Based Inorganic Molecular Tweezers: Metal Recognitions, Ion‐Exchange Interactions and Mechanism Studies

Abstract

This work reports the interesting and unique cation-exchange behaviors of the first indium-bridged purely inorganic 3D framework based on high-nuclearity polyoxoniobates as building units. Each nanoscale polyoxoniobate features a fascinating near-icosahedral core-shell structure with six pairs of unique inorganic "molecular tweezers" that have changeable openings for binding different metal cations via ion-exchanges and exhibit unusual selective metal-uptake behaviors. Further, the material has high chemical stability so that can undergo single-crystal-to-single-crystal metal-exchange processes to produce a dozen new crystals with high crystallinity. Based on these crystals and time-dependent metal-exchange experiments, we can visually reveal the detailed metal-exchange interactions and mechanisms of the material at the atomic precision level. This work demonstrates a rare systematic and atomic-level study on the ion-exchange properties of nanoclusters, which is of significance for the exploration of cluster-based ionexchange materials that are still to be developed.

Photochromic Polyoxoniobates with Photoinduced “D‐f‐A” Electron Transfer Mechanism

“…Usually, in the PONb chemistry, the absorption bands at � 212 and 276 nm are attributed to local excitation of O and charge-transfer transition of O to Nb, respectively. [22] While, in the structure of PONb-Dy-RA, the experimental and computational electronic absorption spectra indicate that the absorption…”

Two Unprecedented Germanoniobate Frameworks Based on High-Nuclearity Peanut-Shaped {Ge12Nb38} Clusters

“…PONbs can display a variety of reactivities, such as coordination chemistry, redox chemistry, and acid–base reactions, making them useful in a number of applications, including photocatalysis, chemical warfare agents, nuclear waste treatment, energy storage materials, and biomedical fields . PONbs have also been investigated in the constructing functional materials and molecular devices …”

Efficient catalysis of Knoevenagel condensation by 1D copper-containing heteropolyoxoniobate at room temperature

“…Inspired by this, the principle of similar solubility may resolve the challenge of low contact frequency between POM catalysts and methylene substrates by connecting organic ligands and POMs. [14][15][16] Transition metal heteroatoms, such as Cu 2+ , can be easily introduced into POMs before modifying with organic ligands, leading to new and efficient organic-inorganic hybrid heteropolyoxometalate catalysts. [17][18][19] Here, we successfully incorporated the Cu(en) complex unit (en = ethylenediamine) into polyoxoniobate in the coordinating mode.…”