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How to achieve CO 2 electroreduction in high efficiency is a current challenge with the mechanism not well understood yet. The metal-organic cages with multiple metal sites, tunable active centers, and well-defined microenvironments may provide a promising catalyst model. Here, we report self-assembly of Ag 4 L 4 type cuboctahedral cages from coordination dynamic Ag + ion and triangular imidazolyl ligand 1,3,5-tris(1-benzylbenzimidazol-2-yl) benzene (Ag-MOC-X, X=NO 3 , ClO 4 , BF 4 ) via anion template effect. Notably, Ag-MOC-NO 3 achieves the highest CO faradaic efficiency in pH-universal electrolytes of 86.1 % (acidic), 94.1 % (neutral) and 95.3 % (alkaline), much higher than those of Ag-MOC-ClO 4 and Ag-MOC-BF 4 with just different counter anions. In situ attenuated total reflection Fourier transform infrared spectroscopy observes formation of vital intermediate *COOH for CO 2 -to-CO conversion. The density functional theory calculations suggest that the adsorption of CO 2 on unsaturated Ag-site is stabilized by C-H⋅⋅⋅O hydrogen-bonding of CO 2 in a microenvironment surrounded by three benzimidazole rings, and the activation of CO 2 is dependent on the coordination dynamics of Ag-centers modulated by the hosted anions through Ag⋅⋅⋅X interactions. This work offers a supramolecular electrocatalytic strategy based on Ag-coordination geometry and host-guest interaction regulation of MOCs as high-efficient electrocatalysts for CO 2 reduction to CO which is a key intermediate in chemical industry process., (© 2024 Wiley-VCH GmbH.)

The self-assembled metal-organic cages (MOCs) have been evolved as a paradigm of enzyme-mimic catalysts since they are able to synergize multifunctionalities inherent in metal and organic components and constitute microenvironments characteristic of enzymatic spatial confinement and versatile host-guest interactions, thus facilitating unconventional organic transformations via unique driving-forces such as weak noncovalent binding and electron/energy transfer. Recently, MOC-based photoreactors emerged as a burgeoning platform of supramolecular photocatalysis, displaying anomalous reactivities and selectivities distinct from bulk solution. This perspective recaps two decades journey of the photoinduced radical reactions by using photoactive metal-organic cages (PMOCs) as artificial reactors, outlining how the cage-confined photocatalysis was evolved from stoichiometric photoreactions to photocatalytic turnover, from high-energy UV-irradiation to sustainable visible-light photoactivation, and from simple radical reactions to multi-level chemo- and stereoselectivities. We will focus on PMOCs that merge structural and functional biomimicry into a single-cage to behave as multi-role photoreactors, emphasizing their potentials in tackling current challenges in organic transformations through single-electron transfer (SET) or energy transfer (EnT) pathways in a simple, green while feasible manner., (© 2024 Wiley‐VCH GmbH.)

A series of isostructural supramolecular cages with a rhombic dodecahedron shape have been assembled with distinct metal-coordination lability (M 8 Pd 6 -MOC-16, M=Ru 2+ , Fe 2+ , Ni 2+ , Zn 2+ ). The chirality transfer between metal centers generally imposes homochirality on individual cages to enable solvent-dependent spontaneous resolution of Δ 8 /Λ 8 -M 8 Pd 6 enantiomers; however, their distinguishable stereochemical dynamics manifests differential chiral phenomena governed by the cage stability following the order Ru 8 Pd 6 >Ni 8 Pd 6 >Fe 8 Pd 6 >Zn 8 Pd 6 . The highly labile Zn centers endow the Zn 8 Pd 6 cage with conformational flexibility and deformation, enabling intrigue chiral-Δ 8 /Λ 8 -Zn 8 Pd 6 to meso-Δ 4 Λ 4 -Zn 8 Pd 6 transition induced by anions. The cage stabilization effect differs from inert Ru 2+ , metastable Fe 2+ /Ni 2+ , and labile Zn 2+ , resulting in different chiral-guest induction. Strikingly, solvent-mediated host-guest interactions have been revealed for Δ 8 /Λ 8 -(Ru/Ni/Fe) 8 Pd 6 cages to discriminate the chiral recognition of the guests with opposite chirality. These results demonstrate a versatile procedure to control the stereochemistry of metal-organic cages based on the dynamic metal centers, thus providing guidance to maneuver cage chirality at a supramolecular level by virtue of the solvent, anion, and guest to benefit practical applications., (© 2023 Wiley-VCH GmbH.)

Herein we demonstrate that, based on the creation of dynamic nanospaces in solution by highly charged positive coordination cage of [Pd 6 (RuL 3 ) 8 ] 28+ , multirole and multi-way cage-confined catalysis is accomplishable for versatile functions and anomalous reactivities with the aid of the biomimetic cage effect. The high cationic-host charges drive partial deprotonation of 24 imidazole-NHs on cage sphere alike imidazole-residuals in proteins, generating amphoteric heterogeneity in solution to enforce effective cavity-basicity against solution-acidity. Synergistic actions arisen from cage hydrophobicity, host-guest electrostatic interactions and imidazole-N coordination facilitate C(sp)-H activation and carbanionic intermediate stabilization of terminal alkynes to achieve unusual H/D-exchange and Glaser coupling under acidic conditions, and enable phase transfers of water-insoluble substrates/products/co-catalysts to make immiscible-phase and bi-phase catalysis feasible, thus providing a useful catalytic protocol to combine merits from homogeneous, heterogeneous, enzymatic and phase transfer catalysis., (© 2021 Wiley-VCH GmbH.)

Although the photodimerization of acenaphthylene (ACE) has been known for 100 years, the asymmetric cycloaddition of its 1-substituted derivatives is unknown. Herein, we report a supramolecular photochirogenic approach in which a homochiral and photoactive Δ/Λ-[Pd 6 (RuL 3 ) 8 ] 28+ metal-organic cage (Δ/Λ-MOC-16) is used as a supramolecular reactor for the enantioselective exited-state photocatalysis of 1-Br-ACE. Owing to preorganization of the substrates by the supramolecular cage, stereochemical control of the triplet state, and nanospace transfer of energy and chirality, the cycloaddition of ACE proceeded with high selectivity for the formation of anti over syn stereoisomers, whereas the regio-, stereo-, and enantioselective cycloaddition of unsymmetrical 1-Br-ACE showed effective enantiodifferentiation of a pair of anti head-to-head stereoisomers. The enzyme-mimicking photocatalysis was verified by catalytic turnover, rate enhancement, and competing-guest inhibition experiments., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A nanocage coupling effect from a redox Ru II -Pd II metal-organic cage (MOC-16) is demonstrated for efficient photochemical H 2 production by virtue of redox-guest modulation of the photo-induced electron transfer (PET) process. Through coupling with photoredox cycle of MOC-16, tetrathiafulvalene (TTF) guests act as electron relay mediator to improve the overall electron transfer efficiency in the host-guest system in a long-time scale, leading to significant promotion of visible-light driven H 2 evolution. By contrast, the presence of larger TTF-derivatives in bulk solution without host-guest interactions results in interference with PET process of MOC-16, leading to inefficient H 2 evolution. Such interaction provides an example to understand the interplay between the redox-active nanocage and guest for optimization of redox events and photocatalytic activities in a confined chemical nanoenvironment., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Molecular or supramolecular level photoluminescence (PL) modulation combining chemical and photonic input/output signals together in an integrated system can provide potential high-density data memorizing and process functions intended for miniaturized devices and machines. Herein, a PL-responsive supramolecular coordination cage has been demonstrated for complex interactions with redox-active guests. PL signals of the cage can be switched and modulated by adding or retracting Fc derivatives or converting TTF into different oxidation states through chemical or photochemical pathways. As a result, reversible or stepwise PL responses are displayed by these host-guest systems because of the occurrence of photoinduced electron-transfer (PET) or fluorescence resonance energy transfer (FREnT) processes, providing unique nanodevice models bearing off/on logic gates or memristor-like sequential memory and Boolean operation functions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)