Ligand‐Directed Template Assembly for the Construction of Gigantic Molybdenum Blue Wheels

Heterometallic AuI 6 AgI 6 Macrocyclic Cluster Templated by a Supramolecular Melamine Dimer

The application of supramolecular templates in aligning atomically precise heterometal arrays is important for pursuing functional materials. Herein, we report that a bilayered supramolecular tri-deprotonated melamine dimer functions as an effective template in the construction of a heterometallic gold(I)-silver(I) macrocyclic cluster [μ6 -(C3 N6 H3 )3- ]2 -AuI 6 AgI 6 . X-ray single crystal structural analysis showed that a crown-like AuI 6 AgI 6 macrocycle is aligned around two parallelly stacked μ6 -(C3 N6 H3 )3- moieties hold together with π-π interactions. Theoretical calculations revealed that the [μ6 -(C3 N6 H3 )3- ]2 motif dominantly contributes to the near-occupied orbitals in the electronic structure, which is closely related to its luminescence properties. This work demonstrates that the supramolecular templates containing multiple symmetric binding sites may present a facile approach in the construction of functional metal clusters.

Gamma-Ray-Induced Formation of Uranyl Peroxide Cage Clusters

Aqueous solutions of lithium uranyl triperoxide, Li₄[UO₂(O₂)₃] (LiUT), were irradiated with gamma rays at room temperature and found to form the uranyl peroxide cage cluster, Li₂₄[(UO₂)(O₂)(OH)]₂₄ (Li-U₂₄). Raman spectroscopy and ¹⁸O labeling were used to identify the Raman-active vibrations of LiUT. With these assignments, the concentration of LiUT was tracked as a function of radiation dose. A discrepancy between monomer removal and cluster formation suggests that the reaction proceeds by the assembly of an intermediate. Non-negative matrix factorization was used to separate Raman spectra into components and resulted in the identification of a unique intermediate species. Much of the conversion appears to be driven by water radiolysis products, particularly the hydroxyl radical. This differs from the ¹⁸O-labeled copper-catalyzed formation of U₂₄, which progresses at a steady rate with no observation of intermediates. Li-U₂₄ in solution decomposes at high radiation doses resulting in a solid insoluble product similar to Na-compreignacite, Na₂(UO₂)₆O₄(OH)₆·7H₂O, which contains uranyl oxyhydroxy sheets.

Macrocyclic Polyoxometalates: Selective Polyanion Binding and Ultrahigh Proton Conduction

The rational development of an anion templation strategy for the construction of macrocycles has been historically limited to small anions, but large polyoxoanions can offer unmatched structural diversity and ample binding sites. Here we report the formation of a {Mo₂₂ Fe₈ } macrocycle by using the Preyssler anion, [NaP₅ W₃₀ O₁₁₀ ]^14- ({P₅ W₃₀ }), as a supramolecular template. The {Mo₂₂ Fe₈ } macrocycle displays selective anion binding behavior in solution. In the solid state, the 1 : 2 host-guest complex, {P₅ W₃₀ }₂ ⊂{Mo₂₂ Fe₈ }, transports protons more effectively, through an extended hydrogen-bonding network, than a related 1 : 1 complex where the guest is completely encapsulated. The results highlight the great potential this anion templation approach has in producing macrocyclic systems for selective anion recognition and proton conduction purposes.

Record Aluminum Molecular Rings for Optical Limiting and Nonlinear Optics

Crystalline cluster materials, a class of functional motif aggregations, provide a great opportunity for tuning the properties stemming from the flexible and accurate variation of inorganic and organic compositions. In this study, we demonstrate the effects of functional ligand and ring size regulation on the structures and third-order nonlinear optical (NLO) properties. Revealed by the single-crystal X-ray analysis results, aluminum molecular ring expansion is achieved by 2×9 and 3×6 strategies. In terms of the given organic shells, we further tuned the aluminum molecular ring sizes from 3.0 nm to 1.7 nm. The picosecond Z-scan measurements results revealed that the third-order NLO performances do not only depend on the general conjugate interactions but are also related to hydrogen bonding, polarizability, and ring sizes. The large nonlinear absorption coefficient and onset prove that the observed samples are promising candidates for the field of nonlinear optics.

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.

Macrocyclic Inorganic Tin-Containing Oxo Clusters: Heterometallic Strategy for Configuration and Catalytic Activity Modulation

In this work, the first examples of inorganic macrocyclic tin-oxo clusters which are stabilized by sulfate ligands are reported. As determined by X-ray diffraction and photoelectron spectroscopy analyses, the prepared inorganic Sn₁₀ -oxo cluster displays interesting mixed valence behaviors, with 8 Sn⁴⁺ located at the cyclic skeleton and two Sn²⁺ encapsulated in the center. When further introducing Ti⁴⁺ and In³⁺ ions to the synthetic systems, heterometallic Sn₂ Ti₆ and SnIn₅ Ti₆ complexes with Ti₆ (SO₄ )₉ and SnIn₅ (SO₄ )₁₂ macrocyclic skeletons were prepared whose configuration and packing models were affected by the ionic radius of incorporated metals. Moreover, comparative CO₂ reduction experiments confirm that such heterometallic composition can significantly improve the catalytic activities of these inorganic macrocyclic oxo clusters. This work represents a milestone in constructing inorganic tin complexes and also macrocyclic metal oxo clusters with tunable configurations and properties.

Designable Aluminum Molecular Rings: Ring Expansion and Ligand Functionalization

Presented herein are the Al^III molecular ring architectures from 8-ring to 16-ring. Although there are numerous reported cyclic coordination compounds based on transition metals, gallium, or lanthanides, the Al versions are less developed due to the fast hydrolysis nature of Al³⁺ ion. With the assistant of monohydric alcohols, a series of atomic precisely Al molecular rings based on benzoates are synthesized. The ring expansion of these Al-rings from 8-ring to 16-ring is related to the monohydric alcohol structure-directing agents. Moreover, the organic ligands on the Al-rings can be modified by using various benzoate derivatives, which lead to tunable surface properties of the Al-rings from hydrophilicity to ultra-hydrophobicity. Importantly, 4-aminobenzoic acid bridged 16-ring is soluble in organic solvents and exhibits high solution stability revealed by mass spectroscopy. Ligand substitution also can be performed between these Al-rings, which reveal controllable ligand functionalization of these Al-rings.

Superior thermally robust energetic materials featuring Z–E isomeric bis(3,4-diamino-1,2,4-triazol-5-yl)-1H-pyrazole: self-assembly nitrogen-rich tubes and templates with Hofmeister anion capture architecture

A super thermally robust nitrogen-rich framework was synthesized, and Z → E isomerization as well as supramolecular assembly inclusion strategy gave rise to two different nitrogen-rich tubes and templates with Hofmeister anions capture architecture.

Augmented polyhydrazone formation in water by template-assisted polymerization using dual-purpose supramolecular templates

Template-assisted polymerization using donor–acceptor supramolecular templates results in higher M_w and M_n values, decreased critical hydrogelation concentrations, and increased gel recovery velocity following shear-induced breakdown.