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Design and self-assembly of hexahedral coordination cages for cascade reactions.

ABSTRACT: The search for supramolecular reactors that contain no catalytically active sites but can promote chemical transformations has received significant attention, but it remains a synthetic challenge. Here we demonstrate a strategy of incorporating bulky and electro-rich aromatic linkers into metallocages to induce cascade reactions. Two hexahedral cages with a framework formula [(Zn₈L₆)(OTf)₁₆] are assembled from six tetrakis-bidentate ligands derived from tetraphenylethylene and eight zinc(II)tris(pyridylimine) centers. The cage cavities can accommodate different molecules such as anthranilamide and aromatic aldehyde through supramolecular interactions, allowing for a cascade condensation and cyclization to produce nonplanar 2,3-dihyroquinazolinones. The reaction is highly efficient with high rate enhancements (up to k_cat/k_uncat?=?38,000) and multiple turnovers compared to the bulk reaction mixture. Control experiments and molecular simulations suggest that the acceleration is attributed to inherent strength of binding affinity for reactants and the release of products to establish catalytic turnover is due to the host-guest geometry discrepancy.

SUBMITTER: Jiao J

PROVIDER: S-EPMC6200784 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Design and self-assembly of wide and robust coordination cages.

Project description:The self-assembly of a new class of coordination cages formed from two tetrapyridyl-substituted cavitands connected through four square-planar palladium or platinum complexes is reported. The shape of the internal cavity resembles an ellipsoid with a calculated volume of 840 A(3). The four lateral portals have a diameter of about 6 A, large enough to allow the fast entrance/egress of counterions in solution. The platinum cages 3a,e cannot be disassembled using triethylamine as competitive ligand and they are kinetically stable at room temperature, whereas the palladium cages 3b-d, 3f-h are disassembled and kinetically labile under the same conditions. The different solubility properties of the cage components have allowed the extension of this self-assembly protocol to the liquid-liquid interface.

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Platinum(II)-Based Convex Trigonal-Prismatic Cages via Coordination-Driven Self-Assembly and C60 Encapsulation.

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Coordination-driven self-assembly of discrete Ru<sub>6</sub>-Pt<sub>6</sub> prismatic cages.

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Coordination-driven self-assembly of M3L2 trigonal cages from preorganized metalloligands incorporating octahedral metal centers and fluorescent detection of nitroaromatics.

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| S-EPMC3071539 | biostudies-literature

Narcissistic, Integrative, and Kinetic Self-Sorting within a System of Coordination Cages.

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Exploiting Coordination Isomerism for Controlled Self-Assembly.

Project description:We exploited the inherent geometrical isomerism of a PtII complex as a new tool to control supramolecular assembly processes. UV irradiation and careful selection of solvent, temperature, and concentration leads to tunable coordination isomerism, which in turn allows fully reversible switching between two distinct aggregate species (1D fibers↔2D lamellae) with different photoresponsive behavior. Our findings not only broaden the scope of coordination isomerism, but also open up exciting possibilities for the development of novel stimuli-responsive nanomaterials.

| S-EPMC6856968 | biostudies-literature

Topological prediction of palladium coordination cages.

Project description:The preparation of functionalized, heteroleptic Pd x L2x coordination cages is desirable for catalytic and optoelectronic applications. Current rational design of these cages uses the angle between metal-binding (∠B) sites of the di(pyridyl)arene linker to predict the topology of homoleptic cages obtained via non-covalent chemistry. However, this model neglects the contributions of steric bulk between the pyridyl residues-a prerequisite for endohedrally functionalized cages, and fails to rationalize heteroleptic cages. We describe a classical mechanics (CM) approach to predict the topological outcomes of Pd x L2x coordination cage formation with arbitrary linker combinations, accounting for the electronic effects of coordination and steric effects of linker structure. Initial validation of our CM method with reported homoleptic Pd12 LFu 24 (LFu = 2,5-bis(pyridyl)furan) assembly suggested the formation of a minor topology Pd15 LFu 30, identified experimentally by mass spectrometry. Application to heteroleptic cage systems employing mixtures of LFu (∠B = 127°) and its thiophene congener LTh (∠B = 149° ∠B exp = 152.4°) enabled prediction of Pd12L24 and Pd24L48 coordination cages formation, reliably emulating experimental data. Finally, the topological outcome for exohedrally (LEx) and endohedrally (LEn) functionalized heteroleptic Pd x L2x coordination cages were predicted to assess the effect of steric bulk on both topological outcomes and coordination cage yields, with comparisons drawn to experimental data.

| S-EPMC8162455 | biostudies-literature

Self-Assembly of Nanoparticles in a Modular Fashion to Prepare Multifunctional Catalysts for Cascade Reactions: From Simplicity to Complexity.

Project description:One-pot cascade reactions can simplify the synthetic route and reduce the use of solvents and energy. The critical part of the completion of the cascade reaction is the preparation of multifunctional catalysts. In this work, a novel and simple pathway was developed to construct multifunctional catalysts with acidic, basic, and magnetic properties at the same time. Mesoporous silica materials modified with different metal oxides were used as catalytic elements. Microspheres that assembled with catalytic components have a diameter of 150 μm and a specific surface area larger than 400 m2 g-1 and can be used as catalysts for cascade reactions. The yield of the final product in the deacetalization-Knoevenagel reaction is 92%. Microspheres integrated with Fe3O4 nanoparticles have a magnetic susceptibility of 7.2 emu g-1 and can be easily removed from the reaction system by applying an external magnetic field. This multimodule assembly method fully reflects the enormous power of complexity resulting from simplicity. This method provides a reference and practical technical support for the preparation of other multifunctional materials.

| S-EPMC6649285 | biostudies-literature

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