Post-synthetic modifications of metal–organic cages

One-Step Coordinating POPD in H3BTB-Sensitized EuMOF-Enabled Tunable Antenna Effects for Fluorescence Turn-On Sensing of Sarin Analogue Vapor

The structural modification of metal-organic frameworks (MOFs) is of vital importance in many fields, especially in sensing with enhanced performance, while the efficient synthesis of functionalized MOF nanoparticles toward small molecule detection remains challenging. Here, a general cellulose nanofibril (CNF)-induced in situ one-step strategy was proposed for the synthesis of dual-ligand-functionalized europium-based MOF (EuMOF@CNF) nanoparticles under an effective regulation of the crystallization kinetics in hydrothermal synthesis. Based on the unique dual-ligand structure, the obtained EuMOF featured a tunable antenna effect and laid a good foundation for fluorescence-sensing materials. Benefiting from the superior self-assembly properties of CNFs and the tunable antenna effect of EuMOF@CNF, flexible sensing films were constructed, showing excellent mechanical properties (72 MPa for stress and 3.8% for strain) and tunable luminescence properties and achieving instant (1 s) and sensitive fluorescence sensing of sarin analogue vapor with a significantly low limit of detection (LOD, 2.8 ppb) and robust selectivity against a wide range of common interferents (>14 types), especially independent of common acids. We believe that this pioneering design of EuMOF with tunable antenna effects would positively advance the development of high-performance MOF-based fluorescent materials and devices.

Hierarchically Self-Assembled Anion-Coordination-Driven Gels for Guest Segregation and Electrical Sensing

The search for macroscopic materials with differentially addressable spaces based on molecular containers has long been driven by their great potential for diverse practical applications pertaining guest selective capture and release. Herein, we report a class of gels (G1-NH2, G1-UPy, G2-NH2, and G2-UPy) that are formed through hierarchical self-assembly of anion-coordinated architectures. The well-defined shapes and sizes of the cavities within anion-coordinated architectures endow the gels with different internal phases, which is beneficial to differentiate the release profiles of guest molecules (dimethylethanolamine, choline, and propyl trimethylammonium) depending on their binding affinity. This study also introduces the concept of flowing a solution containing guests through a host-containing gel for effective guest separation. The process of guest binding could be also monitored in real time via electrical characterization. This work may thus provide a useful strategy for selective solid-phase molecular separation.

Supramolecular Eu(III)4L4 Tetrahedra-Based Films for Luminescence Sensing of Volatile Amines with Sub-ppt-Level Detection Limit

Metal-organic cages are a class of discrete supramolecular architectures endowed with a well-defined cavity and diverse functionalities, offering a broad range of applications that, however, are predominantly confined to liquid phases. In this study, we present the self-assembly of supramolecular Eu(III)4L4 tetrahedra, constructed from triarylborane-cored tritopic tridentate ligands, which were fabricated into spin-coated films with bright emission, smooth surfaces, and uniform thickness. These films demonstrated ultralow detection limits for a series of volatile amines, reaching the sub-ppt level. This work serves as a compelling example of the preparation and application of metal-organic-cage-based films, paving the way for broader application scenarios.

Topological Supramolecular Complexation of Metal-Organic Polyhedra for Tunable Interconnected Hierarchical Microporosity in Amorphous Form

The precise engineering of microporosity is challenging due to the interference at the sub-nm scale from unexpected structural flexibility and molecular packing. Herein, the concept of topological supramolecular complexation is proposed for the feasible fabrication of hierarchical microporosity with broad tunability in amorphous form. The 2.5 nm metal-organic polyhedra (MOP) are complexed with quadridentate ligands through hydrogen and coordination bonding while the mismatch between the MOPs' cuboctahedron and ligands' tetrahedron topology leads to frustrated packing with extrinsic microporosity. Amorphous supramolecular frameworks can be obtained that integrate the intrinsic microporosity of the MOPs with the extrinsic porosity from the frustrated packing. The topologies, sizes and flexibility of ligands as well as ligand/MOP ratios are systemically varied, and the pore size distribution can be precisely adjusted. The hierarchical structures ranging from molecular packing to the morphologies of meso-scale assemblies are probed using ultra-small, small- and wide-angle X-ray scattering, enabling the quantitative evaluation of the micropores interconnectivity for the understanding of gas permeation performance. Gas separation membranes with permselectivity surpassing the Robeson upper bound can be designed. The findings not only give insight into the microscopic mechanism of supramolecular frustrated packing from topological design, but also pave new avenues for the cost-effective fabrications of microporous frameworks.

Tuning the electronic states of Pd(II) defect-engineered metal-organic framework catalysts for efficient conversion of isocyanides

Recently, defective sites in MOFs have become an important tool for tuning the catalytic performance of MOFs. Herein, we report a heterogeneous catalyst "Pd-UiO-67(N)x" by utilizing the active site of defective MOF to modulate the electronic state of Pd, which demonstrates excellent catalytic performances in the oxidative cyclization reaction of isocyanides with o-aminophenols benefiting from the electron-deficient nature of the Pd species. When the Pd loading in defective Pd-UiO-67(N)x system was decreased to 0.37 mol %, the catalytic efficiency was significantly enhanced and the Pd turnover number (TON) increased to 232, which was 27 and 2.6 times higher than that of homogeneous Pd catalysts and defect-free Pd-UiO-67(N)0, respectively. The open pore structure of d-MOFs supports the adsorption of o-aminophenols. Additionally, the domain-limiting effect of the framework restricts the aggregation of Pd, resulting in good stability of the Pd species, which without significant loss of its activity in five consecutive reaction cycles. This work provides an insight into the improvement of stereoelectronic properties of organometallic catalysts through defect-engineered MOFs.

Enhancing carbon enrichment by metal-organic cage to improve the electrocatalytic carbon dioxide reduction performance of silver-based catalyst

Electrochemical reduction of carbon dioxide (CO2) into value-added chemicals provide an alternative technology for achieving carbon neutrality. Limited mass transfer of CO2 in aqueous electrolyte and unsatisfied catalytic activity are the major determinants that inhibit the CO2 conversion at industrial current density level. Herein, an electroreduction-generated metallic Ag atomic clusters supported on metal organic cage (Ag AC/MOC) electrocatalyst is reported to improve the enrichment of inorganic carbon species over catalytic sites for efficient CO2 electroreduction. In-situ infrared spectroscopy and density functional theory studies reveal that the Ag AC/MOC induces the CO2-concentrating in the metal organic cage via a spontaneous ionization of the accumulated CO2, which dramatically enhances the coverage of inorganic carbon species for accelerated kinetic of CO2 conversion. The highly dispersed Ag atomic clusters further reduce the activation energy of CO2 and promote the protonation of CO2 to form carboxyl species, enabling high selectivity toward CO. Hence, the Ag AC/MOC achieves a high CO faradaic efficiency of 97.0 %, while the highest CO partial current reaches 231.6 mA cm-2, which is significantly higher than that of metallic Ag electrocatalyst. This work demonstrates a deep insight into high-performance electrocatalyst design in view of CO2 transfer and catalytic activity.

Single-Step Synthesis of a Heterometallic [Cu2PdL4]2+ Hybrid Metal-Organic Coordination Cage

Traditional methods of assembling low-symmetry heterometallic cage architectures are limited to stepwise construction and combinations of inert and labile metal ions, affording complex, anisotropic cage structures by sacrificing synthetic ease. Herein, a heterometallic [Cu2PdL4]2+ lantern-type cage has been assembled in a single self-assembly step through the use of a heteroditopic ligand with two different metal-binding groups. The resultant cage complex is a fusion of two common lantern-type cage motifs-carboxylate-based metal-organic Cu4L4 cages and pyridyl-based Pd2L4 coordination cages. Evidence for heterometallic cage formation in solution was provided by 1H and diffusion-ordered NMR spectroscopy and electrospray ionization mass spectrometry (ESIMS) data, whereas circular dichroism (CD) spectra confirmed the helical nature of the assembly. The heterometallic cage was then exploited in binding heterotopic guests. It is envisioned that the simple design strategy presented herein will ease the assembly of other structurally complex, low-symmetry cage architectures.

Metal-Organic Frameworks (MOFs): Multifunctional Platforms for Environmental Sustainability

Metal-Organic Frameworks (MOFs) have emerged as versatile materials bridging inorganic and organic chemistry to address critical environmental challenges. Composed of metal nodes and organic linkers, these crystalline structures offer unique properties such as high surface area, tunable pore sizes, and structural diversity. Recent advancements in MOFs synthesis, particularly innovative approaches like mechanochemical, microwave-assisted, and ultrasonic synthesis, have significantly enhanced sustainability by utilizing non-toxic solvents, renewable feedstocks, and energy-efficient processes, offering promising solutions to reduce environmental impact. This review highlights these novel methods and their contributions to improving MOFs functionality for applications in environmental remediation, gas capture, and energy storage. We examine the potential of MOFs in catalysis for pollutant degradation, water purification, and hazardous waste removal, as well as their role in next-generation energy storage technologies, such as supercapacitors, batteries, and hydrogen production. Furthermore, we address challenges including scalability, stability, and long-term performance, underscoring the need for continued innovation in synthesis techniques to enable large-scale MOFs applications. Overall, MOFs hold transformative potential as multifunctional materials, and advancements in synthesis and sustainability are critical for their successful integration into practical environmental and energy solutions.

Incorporation of Cages into Gels: Access to a New Class of Soft Materials with Well-Defined Functionality

The combination of supramolecular self-assemblies and polymer science has resulted in the development of soft materials with diverse properties and applications. In particular, the coordination cages of predefined shape, size, and internal cavity can be utilized intelligently as promising building units for designing responsive and smart soft materials with dual porosity, contributing to the introduction of versatile host-guest chemistry into gels. In this review, we present the recent advancements in gels incorporating coordination cages into their networks, ranging from synthesis strategies to state-of-art applications. In particular, the host-guest chemistry endows the hybrid gel materials with possibilities for guest-specific responsive systems.

Amino-Acid-Induced Circularly Polarized Luminescence of Octahedral Lanthanide Cage

Chiral metal organic cage compounds with excellent circularly polarized luminescent performance have broad application prospects in many fields. Herein, two lanthanide complexes with luminescent properties in the form of racemic hexagonal octahedral cages were synthesized using a tri (β-diketone) ligand. Eu6(C21H6F15O6)8(H2O)6 exhibited red light emission with high quantum yields of 61 %. Then, we successfully synthesized lanthanide compounds with circularly polarized luminescent activity by chiral induction of the racemic mixture with arginine. The luminescence asymmetry factor was 0.53, and the circularly polarized luminescent merit figure reached 0.323. High-performance circularly polarized luminescent of racemic cage like compound systems have achieved using cheap and readily available chiral amino acid molecules through chiral induction.

Mechanically Robust, Durable, and Multifunctional Hyper-Crosslinked Elastomer Based on Metal-Organic-Cluster Crosslinker: The Role of Topological Structure

Polymer materials formed by conventional metal-ligand bonds have very low branch functionality, the crosslinker of such polymer usually consists of 2-4 polymer chains and a single metal ion. Thus, these materials are weak, soft, humidity-sensitive, and unable to withstand their shape under long-term service. In this work, a new hyperbranched metal-organic cluster (MOC) crosslinker containing up to 16 vinyl groups is prepared by a straightforward coordination reaction. Compared with the current typical synthesis of metal-organic cages (MOCs) or metal-organic-polyhedra (MOP) crosslinkers with complex operations and low yield, the preparation of the MOC is simple and gram-scale. Thus, MOC can serve as a high-connectivity crosslinker to construct hyper-crosslinked polymer networks. The as-prepared elastomer exhibits mechanical robustness, creep-resistance, and humidity-stability. Besides, the elastomer possesses self-healing and recyclability at mild condition as well as fluorescence stability. These impressive comprehensive properties are proven to originate from the hyper-crosslinked topological structure and microphase-separated morphology. The MOC-driven hyper-crosslinked elastomers provide a new solution for the construction of mechanically robust, durable, and multifunctional polymers.

Post-synthetic modification of amine-functionalized permanently porous coordination cages

This manuscript explores the post-synthetic modification (PSM) of amine-functionalized porous coordination cages, specifically focusing on the formation of imine bonds through reactions with aldehydes. Targeting various cage topologies, including zirconium-, magnesium-, and molybdenum-based structures, we demonstrate the tunability of cage solubility and porosity through selective functionalization where the proximity of amine groups on the parent cage impacts the extent of modification. The work highlights the reversible nature of imine formation, offering potential applications in solubility switching and mixed-metal solid synthesis.

Functional Post-Synthetic Chemistry of Metal-Organic Cages According to Molecular Architecture and Specific Geometry of Origin

Metal-organic cages (MOCs) are discrete supramolecular entities consisting of metal nodes and organic connectors or linkers; MOCs are noted for their high porosity and processability. Chemically, they can be post-synthetically modified (PSM) and new functional groups can be introduced, presenting attractive qualities, and it is expected that their new properties will differ from those of the original compound. This is why they are highly regarded in the fields of biology and chemistry. The present review deals with the current PSM strategies used for MOCs, including covalent, coordination, and noncovalent methods and their structural benefits. The main emphasis of this review is to show to what extent and under what circumstances a MOC can be designed to obtain a tailored geometric architecture. Although sometimes unclear when examining supramolecular systems, particularizing the design of and systematic approaches to the development and characterization of families of MOCs provides new insights into structure-function relationships, which will guide future developments.

Perylene- and Perylene Diimide-based Framework Materials Constructed through Metal Coordination

Metal-organic frameworks (MOFs) are a class of materials composed of coordinative interactions between metal ions and organic linkers, encompassing two-dimensional (2D), and three-dimensional (3D) architectures. Metal-organic cages (MOCs), a special case of these species, are discrete molecular "capsules" with zero-dimensional (0D) structures. Over the last two decades, MOFs and MOCs composed of organic perylene (P) and perylene diimide (PDI) linkers have gained much attention due to their versatile properties, which can be further enhanced after incorporation into frameworks. This minireview highlights recent progress in the construction and application of P/PDI-based coordination framework materials. The text offers an overview of the synthesis of P/PDI organic linkers, proceeds to their integration into coordination frameworks of different dimensionalities - 2D and 3D MOFs, and 0D MOCs, and then explores potential applications. These include sensing, photocatalysis, electrochemical devices and photothermal conversion and focus on the apparent structure-property relationships. Finally, the challenges and future prospects of P/PDI-derived coordination frameworks will be addressed.

Hypercrosslinked Metal-Organic Polyhedra Electrolyte with High Transference Number and Fast Conduction of Li Ions

Solid-state electrolytes (SSEs) with high Li-ion transference numbers and fast ionic conductivity are urgently needed for technological innovations in lithium-metal batteries. To promote the dissociation of ion pairs and overcome the mechanical brittleness and interface defects caused by traditional fillers in polymeric electrolytes, we designed and fabricated a cationic hypercrosslinking metal-organic polyhedra (HCMOPs) polymer as SSE. Benefiting a three-component synergistic effect: cationic MOPs, branched polyethyleneimine macromonomer and polyelectrolyte units, the Li-HCMOP electrolyte possesses a high Li-ion conductivity, a high Li-ion transference number and a low activation energy. The LiFePO4/Li battery exhibits high capacity with superior rate performance and cycling stability. Moreover, soluble MOPs serve as high crosslinking nodes to provide excellent mechanical strength for electrolytes and good compatibility with polymers. This work highlights an effective idea of high-performance MOP-based solid-state electrolytes applied in LMBs.

Tunable synthesis of heteroleptic zirconium-based porous coordination cages

Zirconium-based porous coordination cages have been widely studied and have shown to be potentially useful for many applications as a result of their tunability and stability, likely as a result of their status as a molecular equivalent to the small 8 Å tetrahedral pores of UiO-66 (Zr6(μ3-O)4(μ2-OH)4(C8O4H4)6). Functional groups attached to these molecular materials endow them with a range of tunable properties. While so-called multivariate MOFs containing multiple types of functional groups on different bridging ligands within a structure are common, incorporating multiple functional moieties in permanently microporous molecular materials has proved challenging. By applying a mixed-ligand, or heteroleptic, synthesis strategy to cage formation, we have designed a straight-forward, one-pot synthesis of 10 Å zirconium-based molecular cages in a basket-shaped, or Zr12L6, geometry containing 3 : 3 ratios of combinations of two types of functional moieties from 11 different ligand options. Additionally, using more sterically hindered ligands, such as 5-benzyloxybenzene dicarboxylate, we show that ligand size governs the resulting cage geometry. This method allows for multiple functional groups to be incorporated in molecular cages and the ratio of moieties incorporated can be easily controlled. With this strategy in hand, we show that ligands for which zirconium cage syntheses have been elusive, such as 2,5-dihydroxybenzene dicarboxylate, have now been successfully incorporated into porous structures.

Assembling a new generation of radiopharmaceuticals with supramolecular theranostics

Supramolecular chemistry has been used to tackle some of the major challenges in modern science, including cancer therapy and diagnosis. Supramolecular platforms provide synthetic flexibility, rapid generation through self-assembly, facile labelling, unique topologies, tunable reversibility of the enabling noncovalent interactions, and opportunities for host-guest chemistry and mechanical bonding. In this Review, we summarize recent advances in the design and radiopharmaceutical application of discrete self-assembled coordination complexes and mechanically interlocked molecules - namely, metallacages and rotaxanes, respectively - as well as in situ-forming supramolecular aggregates, specifically pinpointing their potential as next-generation radiotheranostic agents. The outlook of such supramolecular constructs for potential applications in the clinic is discussed.

Double-Bridging Increases the Stability of Zinc(II) Metal-Organic Cages

A key feature of coordination cages is the dynamic nature of their coordinative bonds, which facilitates the synthesis of complex polyhedral structures and their post-assembly modification. However, this dynamic nature can limit cage stability. Increasing cage robustness is important for real-world use cases. Here we introduce a double-bridging strategy to increase cage stability, where designed pairs of bifunctional subcomponents combine to generate rectangular tetratopic ligands within pseudo-cubic Zn8L6 cages. These cages withstand transmetalation, the addition of competing ligands, and nucleophilic imines, under conditions where their single-bridged congeners decompose. Our approach not only increases the stability and robustness of the cages while maintaining their polyhedral structure, but also enables the incorporation of additional functional units in proximity to the cavity. The double-bridging strategy also facilitates the synthesis of larger cages, which are inaccessible as single-bridged congeners.

Ideal Bi-Based Hybrid Anode Material for Ultrafast Charging of Sodium-Ion Batteries at Extremely Low Temperatures

Sodium-ion batteries have emerged as competitive substitutes for low-temperature applications due to severe capacity loss and safety concerns of lithium-ion batteries at - 20 °C or lower. However, the key capability of ultrafast charging at ultralow temperature for SIBs is rarely reported. Herein, a hybrid of Bi nanoparticles embedded in carbon nanorods is demonstrated as an ideal material to address this issue, which is synthesized via a high temperature shock method. Such a hybrid shows an unprecedented rate performance (237.9 mAh g-1 at 2 A g-1) at - 60 °C, outperforming all reported SIB anode materials. Coupled with a Na3V2(PO4)3 cathode, the energy density of the full cell can reach to 181.9 Wh kg-1 at - 40 °C. Based on this work, a novel strategy of high-rate activation is proposed to enhance performances of Bi-based materials in cryogenic conditions by creating new active sites for interfacial reaction under large current.

Topological control in paddlewheel metal-organic cages via ligand length variation

Varying the length of phenanthrene-derived ligands switches the selective assembly of MIInLn metal-organic cages (MOCs, n = 6 or 8) between tetrahedral, square, or triangular architectures. The limit of this approach is explored for both Cu2 and Rh2 paddlewheel MOCs, and supported by solution, solid-state and computational analysis.

Enhancing Performances of Enzyme/Metal-Organic Polyhedra Composites by Mixed-Protein Co-Immobilization

Protein immobilization using water-soluble ionic metal-organic polyhedra (MOPs) acting as porous spacers has recently been demonstrated as a potent strategy for the preparation of biocatalysts. In this article, we describe a mixed-protein approach to achieve biocomposites with adjustable enzyme contents and excellent immobilization efficiencies, in a systematic and well-controlled manner. Self-assembly of either cationic or anionic MOPs with bovine serum albumin or egg white lysozyme combined with enzymes (alkaline phosphatase, laccase or cytochrome c) led to solid-state catalysts with a high retention of enzyme activity. Furthermore, for all these systems, the dilution of enzymes within the solid-state composite led to noticeably improved catalytic performances, with both higher specific activity and affinity for substrate.

Terpyridine-Based Metal-Organic Cage with Enhanced Emission via Coordination-Induced Rigidity

Realizing the regulation of photophysical properties by precisely controlling the molecular composition and configuration, thereby obtaining high-performance optical materials, remains of great significance. Due to the directionality and reversibility of the coordination bond, coordination-driven self-assembly endows the molecule with customized thermodynamically stable structures and desired properties. In this paper, a luminous metal-organic cage [Zn12L6] (S) was elaborately designed and quantitatively synthesized by self-assembly of tetrapodal TQPP chromophore-containing terpyridine ligand L with Zn2+. Complex S possessed a rigid cage-like structure, which endows a higher fluorescence quantum efficiency both in solution (∼88%) and neat solid (16%) than the corresponding ligand L. Further, using complex S as the photoactive component, two light-emitting diodes (LEDs) were successfully fabricated and the emission of pure white light (CIE coordinates: 0.3341, 0.3300) was achieved. These results afford a method to obtain enhanced luminescence performance via the formation of rigid coordination-driven supramolecular architectures.

Understanding the Selective Removal of Perfluoroalkyl and Polyfluoroalkyl Substances via Fluorine-Fluorine Interactions: A Critical Review

As regulatory standards for per- and polyfluoroalkyl substances (PFAS) become increasingly stringent, innovative water treatment technologies are urgently demanded for effective PFAS removal. Reported sorbents often exhibit limited affinity for PFAS and are frequently hindered by competitive background substances. Recently, fluorinated sorbents (abbreviated as fluorosorbents) have emerged as a potent solution by leveraging fluorine-fluorine (F···F) interactions to enhance selectivity and efficiency in PFAS removal. This review delves into the designs and applications of fluorosorbents, emphasizing how F···F interactions improve PFAS binding affinity. Specifically, the existence of F···F interactions results in removal efficiencies orders of magnitude higher than other counterpart sorbents, particularly under competitive conditions. Furthermore, we provide a detailed analysis of the fundamental principles underlying F···F interactions and elucidate their synergistic effects with other sorption forces, which contribute to the enhanced efficacy and selectivity. Subsequently, we examine various fluorosorbents and their synthesis and fluorination techniques, underscore the importance of accurately characterizing F···F interactions through advanced analytical methods, and emphasize the significance of this interaction in developing selective sorbents. Finally, we discuss challenges and opportunities associated with employing advanced techniques to guide the design of selective sorbents and advocate for further research in the development of sustainable and cost-effective treatment technologies leveraging F···F interactions.

Supramolecular Complexation Reinforced Polymer Frustrated Packing: Controllable Dual Porosity for Improved Permselectivity of Coordination Nanocage Mixed Matrix Membranes

The developments of mixed matrix membranes (MMMs) are severely hindered by the complex inter-phase interaction and the resulting poor utilization of inorganics' microporosity. Herein, a dual porosity framework is constructed in MMMs to enhance the accessibility of inorganics' microporosity to external gas molecules for the effective application of microporosity for gas separation. Nanocomposite organogels are first prepared from the supramolecular complexation of rigid polymers and 2 nm microporous coordination nanocages (CNCs). The network structures can be maintained with microporous features after solvent removal originated from the rigid nature of polymers, and the strong coordination and hydrogen bond between the two components. Moreover, the strong supramolecular attraction reinforces the frustrated packing of the rigid polymers on CNC surface, leading to polymer networks' extrinsic pores and the interconnection of CNCs' micro-cavities for the fast gas transportation. The gas permeabilities of the MMMs are 869 times for H2 and 1099 times for CO2 higher than those of pure polymers. The open metal sites from nanocage also contribute to the enhanced gas selectivity and the overall performance surpasses 2008 H2/CO2 Robeson upper bound. The supramolecular complexation reinforced packing frustration strategy offers a simple and practical solution to achieve improved gas permselectivity in MMMs.

From individuals to families: design and application of self-similar chiral nanomaterials

Establishing an intimate relationship between similar individuals is the beginning of self-extension. Various self-similar chiral nanomaterials can be designed using an individual-to-family approach, accomplishing self-extension. This self-similarity facilitates chiral communication, transmission, and amplification of synthons. We focus on describing the marriage of discrete cages to develop self-similar extended frameworks. The advantages of utilizing cage-based frameworks for chiral recognition, enantioseparation, chiral catalysis and sensing are highlighted. To further promote self-extension, fractal chiral nanomaterials with self-similar and iterated architectures have attracted tremendous attention. The beauty of a fractal family tree lies in its ability to capture the complexity and interconnectedness of a family's lineage. As a type of fractal material, nanoflowers possess an overarching importance in chiral amplification due to their large surface-to-volume ratio. This review summarizes the design and application of state-of-the-art self-similar chiral nanomaterials including cage-based extended frameworks, fractal nanomaterials, and nanoflowers. We hope this formation process from individuals to families will inherit and broaden this great chirality.

Metal Ions Trigger the Gelation of Cysteine-Containing Peptide-Appended Coordination Cages

We report a series of coordination cages that incorporate peptide chains at their vertices, prepared through subcomponent self-assembly. Three distinct heterochiral tripeptide subcomponents were incorporated, each exhibiting an L-D-L stereoconfiguration. Through this approach, we prepared and characterized three tetrahedral metal-peptide cages that incorporate thiol and methylthio groups. The gelation of these cages was probed through the binding of additional metal ions, with the metal-peptide cages acting as junctions, owing to the presence of sulfur atoms on the peripheral peptides. Gels were obtained with cages bearing cysteine at the C-terminus. Our strategy for developing functional metal-coordinated supramolecular gels with a modular design may result in the development of materials useful for chemical separations or drug delivery.

Proton-Induced Reversible Spin-State Switching in Octanuclear FeIII Spin-Crossover Metal-Organic Cages

Responsive spin-crossover (SCO) metal-organic cages (MOCs) are emerging dynamic platforms with potential for advanced applications in magnetic sensing and molecular switching. Among these, FeIII-based MOCs are particularly noteworthy for their air stability, yet they remain largely unexplored. Herein, we report the synthesis of two novel FeIII MOCs using a bis-bidentate ligand approach, which exhibit SCO activity above room temperature. These represent the first SCO-active FeIII cages and feature an atypical {FeN6}-type coordination sphere, uncommon for FeIII SCO compounds. Our study reveals that these MOCs are sensitive to acid/base variations, enabling reversible magnetic switching in solution. The presence of multiple active proton sites within these SCO-MOCs facilitates multisite, multilevel proton-induced spin-state modulation. This behavior is observed at room temperature through 1H NMR spectroscopy, capturing the subtle proton-induced spin-state transitions triggered by pH changes. Further insights from extended X-ray absorption fine structure (EXAFS) and theoretical analyses indicate that these magnetic alterations primarily result from the protonation and deprotonation processes at the NH active sites on the ligands. These processes induce changes in the secondary coordination sphere, thereby modulating the magnetic properties of the cages. The capability of these FeIII MOCs to integrate magnetic responses with environmental stimuli underscores their potential as finely tunable magnetic sensors and highlights their versatility as molecular switches. This work paves the way for the development of SCO-active materials with tailored properties for applications in sensing and molecular switching.

Recyclable Homogeneous Catalysis Enabled by Dynamic Coordination on Rhodium(II) Axial Sites of Metal-Organic Polyhedra

The activity of catalytic nanoparticles is strongly dependent on their surface chemistry, which controls colloidal stability and substrate diffusion toward catalytic sites. In this work, we studied how the outer surface chemistry of nanostructured Rh(II)-based metal-organic cages or polyhedra (Rh-MOPs) impacts their performance in homogeneous catalysis. Specifically, through post-synthetic coordination of aliphatic imidazole ligands onto the exohedral Rh(II) axial sites of Rh-MOPs, we solubilized a cuboctahedral Rh-MOP in dichloromethane, thereby enabling its use as a homogeneous catalyst. We demonstrated that the presence of the coordinating ligand on the surface of the Rh-MOP does not hinder its catalytic activity in styrene aziridination and cyclopropanation reactions, thanks to the dynamic Rh-imidazole coordination bond. Finally, we used similar ligand exchange post-synthetic reactions to develop a ligand-mediated approach for precipitating the Rh-MOP catalyst, facilitating the recovery and reuse of Rh-MOPs as homogeneous catalysts.

A Cages-on-Cluster Structure Constructed by Post-Clustering Covalent Modifications and Guest-Enabled Stimuli-Responsive Luminescence

A gold(I)-cluster-based twin-cage has been constructed by post-clustering covalent modification of a hexa-aldehyde cluster precursor with triaminotriethylamines. The cages-on-cluster structure has double cavities and four binding sites, which show site-discriminative binding for silver(I) and copper(I) guests. The guests in the tripodal hats affect the luminescence of the cluster: the tetra-silver(I) host-guest complex is weakly red-emissive, while the bis-copper(I)-bis-silver(I) one is non-emissive but is a stimuli-responsive supramolecule. The copper(I) ion inside the tri-imine cavity is oxidation sensitive, which enables the release of the bright emissive precursor cluster triggered by H2O2 solution. The hybridization of a cluster with cavities to construct a cluster-based cage presents an innovative concept for functional cluster design, and the post-clustering covalent modification opens up new avenues for finely tuning the properties of clusters.

An Encyclopedic Compendium on Chemosensing Supramolecular Metal-Organic Gels

Chemosensing, an interdisciplinary scientific domain, plays a pivotal role ranging from environmental monitoring to healthcare diagnostics and (inter)national security. Metal-organic gels (MOGs) are recognized for their stability, selectivity, and responsiveness, making them valuable for chemosensing applications. Researchers have explored the development of MOGs based on different metal ions and ligands, allowing for tailored properties and sensitivities, and have even demonstrated their applications as portable sensors such as paper-based test strips for practical use. Herein, several studies related to MOGs development and their applications in the chemosensing field via UV-visible or luminance along with electrochemical approach are presented. These papers explored MOGs as versatile materials with their use in sensing bio or environmental analytes. This review provides a foundational understanding of key concepts, methodologies, and recent advancements in this field, fostering the scientific community.

Cage-To-Cage Transformations in Self-Assembled Coordination Cages Using "Acid/Base" or "Guest Binding-Induced Strain" as Stimuli

Controlling supramolecular systems between different functional forms by utilizing acids/bases as stimuli is a formidable challenge, especially where labile coordination bonds are involved. A pair of acid/base responsive, interconvertible 1,5-enedione/pyrylium based Pd2L4-type cages are prepared that exhibit differential guest binding abilities towards disulfonates of varied sizes. A three-state switch has been achieved, where (i) a weakly coordinating base induced cage-to-cage transformation in the first step, (ii) a strongly coordinating base triggered cage disassembly as the second step, and (iii) the third step shows acid(strong) promoted generation of initial cage, thereby completing the cycle. To our surprise, binding of a specific disulfonate guest facilitated cage-to-cage transformations by inducing strain on the cage assembly thereby opening the labile pyrylium rings of the cage. Through a competitive guest binding study, we demonstrated the superior guest binding capability of the octacationic pyrylium-based cage over a similar-sized tetracationic cage. These results provide a reliable approach to reversibly modulate the guest binding properties of acid/base-responsive self-assembled coordination cages.

Unlocking High Porosity: Post-Synthetic Solvothermal Treatment of Cu-Paddlewheel Based Metal-Organic Cages

Metal-organic cages (MOCs) have garnered significant attention due to their unique discrete structures, intrinsic porosity, designability, and tailorability. However, weak inter-cage interactions, such as van der Waals forces and hydrogen bonding can cause solid-state MOCs to lose structural integrity during desolvation, leading to the loss of porosity. In this work, a novel strategy to retain the permanent porosity of Cu-paddlewheel-based MOCs, enabling their use as heterogeneous catalysts is presented. Post-synthetic solvothermal treatments in non-coordinating solvents, mesitylene, and p-xylene, effectively preserve the packing structures of solvent-evacuated MOCs while preventing cage agglomeration. The resulting MOCs exhibit an exceptional N2 sorption capacity, with a high surface area (SBET = 1934 m2 g-1 for MOP-23), which is among the highest reported for porous MOCs. Intriguingly, while the solvothermal treatment reduced Cu(II) to Cu(I) in the Cu-paddlewheel clusters, the MOCs with mixed-valenced Cu(I)/Cu(II) maintained their crystallinity and permanent porosity. The catalytic activities of these MOCs are successfully examined in copper(I)-catalyzed hydrative amide synthesis, highlighting the prospect of MOCs as versatile reaction platforms.

Metal-organic frameworks as candidates for tumor sonodynamic therapy: Designable structures for targeted multifunctional transformation

Sonodynamic therapy (SDT), utilizing ultrasound (US) as the trigger, has gained popularity recently as a therapeutic approach with significant potential for treating various diseases. Metal-organic frameworks (MOFs), characterized by structural flexibility, are prominently emerging in the SDT realm as an innovative type of sonosensitizer, offering functional tunability and biocompatibility. However, due to the inherent limitations of MOFs, such as low reactivity to reactive oxygen species and challenges posed by the complex tumor microenvironment, MOF-based sonosensitizers with singular functions are unable to demonstrate the desired therapeutic efficacy and may pose risks of toxicity, limiting their biological applications to superficial tissues. MOFs generally possess distinctive crystalline structures and properties, and their controlled coordination environments provide a flexible platform for exploring structure-effect relationships and guiding the design and development of MOF-based nanomaterials to unlock their broader potential in biological fields. The primary focus of this paper is to summarize cases involving the modification of different MOF materials and the innovative strategies developed for various complex conditions. The paper outlines the diverse application areas of functionalized MOF-based sonosensitizers in tumor synergistic therapies, highlighting the extensive prospects of SDT. Additionally, challenges confronting SDT are briefly summarized to stimulate increased scientific interest in the practical application of MOFs and the successful clinical translation of SDT. Through these discussions, we strive to foster advancements that lead to early-stage clinical benefits for patients. STATEMENT OF SIGNIFICANCE: 1. An overview for the progresses in SDT explored from a novel and fundamental perspective. 2. Different modification strategies to improve the MOFs-mediated SDT efficacy are provided. 3. Guidelines for the design of multifunctional MOFs-based sonosensitizers are offered. 4. Powerful tumor ablation potential is reflected in SDT-led synergistic therapies. 5. Future challenges in the field of MOFs-based SDT in clinical translation are suggested.

Solvents regulate the packing porosity of a bilayer metal-organic cage

Metal-organic cages (MOCs) are an emerging class of porous materials with promising applications. However, controlling the configuration of the cage packing, which can influence the overall porosity of the materials, remains a difficulty, as many factors can influence the cage assembly and stacking. Herein, we report a solvent strategy to fine-tune the packing configuration of a bilayer MOC, a small triangular prism cage (six Cu ions act as vertices, three nitrate ions act as pillars, and six nitrate ions act as caps) incorporated into a large triangular prism cage (another six Cu ions act as vertices, a couple of oxygen atoms act as pillars and six ligands (L1: 3,5-bis(pyridine-3-yl)-4H-1,2,4-triazole) act as a jointed cap) by the coordination between the triazole nitrogen from L1 and the inner vertex Cu ions. The involved solvents water, acetonitrile (MeCN) and N,N'-dimethylformamide (DMF) form hydrogen bonds with this bilayer MOC, resulting in three different types of packing associated with systemically tuned porosity (NTU-93: 12.2%, NTU-94: 19.3%, and NTU-95: 42.1%). Gas adsorption and breakthrough tests demonstrate that NTU-95 has potential ability for C2H2/C2H4 separation. This work not only shows a case of finely tuned packing of coordination cages, but also provides a powerful tool that may be extended to other cage families.

Dimensional Reduction of Metal-Organic Frameworks for Photocatalytic Synthesis of Fused Tetracyclic Heterocycles

Heterogeneous palladium catalysts with high efficiency, high Pd atom utilization, simplified separation, and recycle have attracted considerable attention in the field of synthetic chemistry. Herein, we reported a zirconium-based two-dimensional metal-organic framework (2D-MOF)-based Pd(II) photocatalyst (Zr-Ir-Pd) by merging the Ir photosensitizers and Pd(II) species into the skeletons of the 2D-MOF for the Pd(II)-catalyzed oxidation reaction. Morphological and structural characterization identified that Zr-Ir-Pd with a specific nanoflower-like structure consists of ultrathin 2D-MOF nanosheets (3.85 nm). Due to its excellent visible-light response and absorption capability, faster transfer and separation of photogenerated carriers, more accessible Pd active sites, and low mass transfer resistance, Zr-Ir-Pd exhibited boosted photocatalytic activity in catalyzing sterically hindered isocyanide insertion of diarylalkynes for the construction of fused tetracyclic heterocycles, with up to 12 times the Pd catalyst turnover number than the existing catalytic systems. In addition, Zr-Ir-Pd inhibited the competitive agglomeration of Pd(0) species and could be reused at least five times, owing to the stabilization of 2D-MOF on the single-site Pd and Ir sites. Finally, a possible mechanism of the photocatalytic synthesis of fused tetracyclic heterocycles catalyzed by Zr-Ir-Pd was proposed.

Precise Post-Synthetic Modification of Heterometal-Organic Capsules for Selectively Encapsulating Tetrahedral Anions

Post-synthetic modification plays a crucial role in precisely adjusting the structure and functions of advanced materials. Herein, we report the self-assembly of a tubular heterometallic Pd3Cu6L16 capsule that incorporates Pd(II) and CuL1 metalloligands. This capsule undergoes further modification with two tridentate anionic ligands (L2) to afford a bicapped Pd3Cu6L16L22 capsule with an Edshammer polyhedral structure. By employing transition metal ions, acid, and oxidation agents, the bicapped capsule can be converted into an uncapped one. This uncapped form can then revert back to the bicapped structure on the addition of Br- ions and a base. Interestingly, introducing Ag+ ions leads to the removal of one L2 ligand from the bicapped capsule, yielding a mono-capped Pd3Cu6L16L2 structure. Furthermore, the size of the anions critically influences the precise control over the post-synthetic modifications of the capsules. It was demonstrated that these capsules selectively encapsulate tetrahedral anions, offering a novel approach for the design of intelligent molecular delivery systems.

Baicalin nanodelivery system based on functionalized metal-organic framework for targeted therapy of osteoarthritis by modulating macrophage polarization

Intra-articular drugs used to treat osteoarthritis (OA) often suffer from poor pharmacokinetics and stability. Nano-platforms as drug delivery systems for drug delivery are promising for OA therapy. In this study, we reported an M1 macrophage-targeted delivery system Bai@FA-UIO-66-NH2 based on folic acid (FA) -modified metal-organic framework (MOF) loaded with baicalin (Bai) as antioxidant agent for OA therapy. With outstanding biocompatibility and high drug loading efficiency, Bai@FA-UIO-66-NH2 could be specifically uptaken by LPS-induced macrophages to serve as a potent ROS scavenger, gradually releasing Bai at the subcellular level to reduce ROS production, modulate macrophage polarization to M2, leading to alleviation of synovial inflammation in OA joints. The synergistic effect of Bai@FA-UIO-66-NH2 on macrophage polarization and ROS scavenging significantly improved the therapeutic efficacy of OA, which may provide a new insight into the design of OA precision therapy.

Humidity-Induced Self-Oscillating and Self-Healing Hypercrosslinked Metal-Organic Polyhedra Membranes

Designing autonomously oscillating materials is highly desirable for emerging smart material fields but challenging. Herein, a type of hypercrosslinked metal-organic polyhedra (HCMOPs) membranes formed by covalent crosslinking of boronic acid-modified Zr-based MOPs with polyvinyl alcohol (PVA) are rationally designed. In these membranes, MOPs serve as high-connectivity nodes and provide dynamic borate bonds with PVA in hypercrosslinked networks, which can be broken/formed reversibly upon the stimulus of water vapor. The humidity response characteristic of HCMOPs promotes their self-oscillating and self-healing properties. HCMOP membranes can realize a self-oscillating property above the water surface even after loading a cargo that is 1.5 times the weight of the membrane due to the fast adsorption and desorption kinetics. Finally, the HCMOP actuator can realize energy conversion from mechanical energy into electricity when coupled with a piezoelectric membrane. This work not only paves a new avenue to construct MOP-polymer hybrid materials but also expands the application scopes of MOPs for smart actuation devices.

Covalent Post-Synthetic Modification of Metal-Organic Cages: Concepts and Recent Progress

Metal-organic cages (MOCs) are supramolecular coordination complexes that have internal cavities for hosting guest molecules and exhibiting various properties. However, the functions of MOCs are limited by the choice of the building blocks. Post-synthetic modification (PSM) is a technique that can introduce new functional groups and replace existing ones on the MOCs without changing their geometry. Among many PSM methods, covalent PSM is a promising approach to modify MOCs with tailored structures and functions. Covalent PSM can be applied to either the internal cavity or the external surface of the MOCs, depending on the functionality expected to be customized. However, there are still some challenges and limitations in the field of covalent PSM of MOCs, such as the balance between the stability of MOCs and the harshness of organic reactions involved in covalent PSMs. This concept article introduces the organic reaction types involved in covalent PSM of MOCs, their new applications after modification, and summarizes and provides an outlook of this research field.

Stabilization of Lantern-Type Metal-Organic Cages (MOCs) by Protective Control of Ligand Exchange Rates

Self-assembling systems in nature display remarkable complexity with assemblies of different sub-units to generate functional species. Synthetic analogues of such systems are a challenge, often requiring the ability to bias distributions that are under thermodynamic assembly control. Using lantern-type MOCs (metal-organic cages) as a prototypical self-assembling system, herein we explore the role that steric bulk plays in controlling the exchange rate of ligands in paddlewheel-based assemblies, and thus the stability of cages, in competitive self-assembling scenarios. The effective lifetime of the lantern-type MOCs varies over an order of magnitude depending on the steric bulk proximal to the metal nodes with lifetimes of the cages ranging from tens of minutes to several hours. The bulk of the coordinating solvents likewise reduces the rate of ligand exchange, and thus yields longer-lived species. Understanding this subtle effect has implications for controlling the stability of complex assemblies in competitive environments with implications for guest release and application.

Fabrication of Self-Expanding Metal-Organic Cages Using a Ring-Openable Ligand

Metal-organic cages (MOCs), which are formed via coordination-driven assembly, are being extensively developed for various applications owing to the utility of their accessible molecular-sized cavity. While MOC structures are uniquely and precisely predetermined by the metal coordination number and ligand configuration, tailoring MOCs to further modulate the size, shape, and chemical environment of the cavities has become intensively studied for a more efficient and adaptive molecular binding. Herein, we report self-expanding MOCs that exhibit remarkable structural variations in cage size and flexibility while maintaining their topology. A cyclic ligand with an oligomeric chain tethering the two benzene rings of stilbene was designed and mixed with RhII ions to obtain the parent MOCs. These MOCs were successfully transformed into expanded MOCs via the selective cleavage of the double bond in stilbene. The expanded MOCs could effectively trap multidentate N-donor molecules in their enlarged cavity, in contrast to the original MOCs with a narrow cavity. As the direct synthesis of expanded MOCs is impractical because of the entropically disfavored structures, self-expansion using ring-openable ligands is a promising approach that allows precision engineering and the production of functional MOCs that would otherwise be inaccessible.

Bridging the Homogeneous and Heterogeneous Catalysis by Supramolecular Metal-Organic Cages with Varied Packing Modes

Integrating the advantages of homogeneous and heterogeneous catalysis has proved to be an optimal strategy for developing catalytic systems with high efficiency, selectivity, and recoverability. Supramolecular metal-organic cages (MOCs), assembled by the coordination of metal ions with organic linkers into discrete molecules, have performed solvent processability due to their tunable packing modes, endowing them with the potential to act as homogeneous or heterogeneous catalysts in different solvent systems. Here, the design and synthesis of a series of stable {Cu3} cluster-based tetrahedral MOCs with varied packing structures are reported. These MOCs, as homogeneous catalysts, not only show high catalytic activity and selectivity regardless of substrate size during the CO2 cycloaddition reaction, but also can be easily recovered from the reaction media through separating products and co-catalysts by one-step work-up. This is because that these MOCs have varied solubilities in different solvents due to the tunable packing of MOCs in the solid state. Moreover, the entire catalytic reaction system is very clean, and the purity of cyclic carbonates is as high as 97% without further purification. This work provides a unique strategy for developing novel supramolecular catalysts that can be used for homogeneous catalysis and recycled in a heterogeneous manner.

Macrocycle-Based Hierarchically Porous Hydrogen-Bonded Organic Frameworks

Hydrogen-bonded organic frameworks (HOFs) are porous crystalline materials. The pores in HOFs are usually non-covalent extrinsic pores constructed through the formation of the framework. Supramolecular macrocycles with intrinsic pores in their structures are good candidates for constructing HOFs with intrinsic pores from the macrocycles themselves, thus leading to hierarchically porous structures. Combining the macrocycle and HOFs will endow these hierarchically porous materials with enhanced properties and special functionalities. This review summarizes recent advances in macrocycle-based HOFs, including the macrocycles used for constructing HOFs, the hierarchically porous structures of the HOFs, and the applications induced by the hierarchically HOFs porous structures. This review provides insights for future research on macrocycle-based hierarchically porous HOFs and the appropriate applications of the unique structures.

Design and application of dual-emission metal-organic framework-based ratiometric fluorescence sensors

Metal-organic frameworks (MOFs) are novel inorganic-organic hybridized crystals with a wide range of applications. In the last twenty years, fluorescence sensing based on MOFs has attracted much attention. MOFs can exhibit luminescence from metal nodes, ligands or introduced guests, which provides an excellent fluorescence response in sensing. However, single-signal emitting MOFs are susceptible to interference from concentration, environment, and excitation intensity, resulting in poor accuracy. To overcome the shortcomings, dual-emission MOF-based ratiometric fluorescence sensors have been proposed and rapidly developed. In this review, we first introduce the luminescence mechanisms, synthetic methods, and detection mechanisms of dual-emission MOFs, highlight the strategies for constructing ratiometric fluorescence sensors based on dual-emission MOFs, and classify them into three categories: intrinsic dual-emission and single-emission MOFs with luminescent guests, and non-emission MOFs with other luminescent materials. Then, we summarize the recent advances in dual-emission MOF-based ratiometric fluorescence sensors in various analytical industries. Finally, we discuss the current challenges and prospects for the future development of these sensors.

Automated Structural Activity Screening of β-Diketonate Assemblies with High-Throughput Ion Mobility-Mass Spectrometry

Embracing complexity in design, metallo-supramolecular self-assembly presents an opportunity for fabricating materials of economic significance. The array of accessible supramolecules is alluring, along with favourable energy requirements. Implementation is hampered by an inability to efficiently characterise complex mixtures. The stoichiometry, size, shape, guest binding properties and reactivity of individual components and combinations thereof are inherently challenging to resolve. A large combinatorial library of four transition metals (Fe, Cu, Ni and Zn), and six β-diketonate ligands at different molar ratios and pH was robotically prepared and directly analysed over multiple timepoints with electrospray ionisation travelling wave ion mobility-mass spectrometry. The dataset was parsed for self-assembling activity without first attempting to structurally assign individual species. Self-assembling systems were readily categorised without manual data-handling, allowing efficient screening of self-assembly activity. This workflow clarifies solution phase supramolecular assembly processes without manual, bottom-up processing. The complex behaviour of the self-assembling systems was reduced to simpler qualities, which could be automatically processed.

Heterometallic cages: synthesis and applications

High symmetry metallosupramolecular architectures (MSAs) have been exploited for a range of applications including molecular recognition, catalysis and drug delivery. Recently there have been increasing efforts to enhance those applications by generating reduced symmetry MSAs. While there are several emerging methods for generating lower symmetry MSAs, this tutorial review examines the general methods used for synthesizing heterometallic MSAs with a particular focus on heterometallic cages. Additionally, the intrinsic properties of the cages and their potential emerging applications as host-guest systems and reaction catalysts are described.

Utility of all-pyrazole heteroscorpionates in f-element chemistry

Since their discovery in 1966, scorpionate ligands have been utilized to make coordination compounds for a variety of applications such as: studying organometallic reactions, biomimetic complexes, light-emitting materials and single-ion magnets. The recent development of a solvent-free pyrazole substitution chemistry has yielded the quantitative synthesis of asymmetrically functionalized all-pyrazole heteroscorpionate ligands. In this frontier article, we highlight the utility of all-pyrazole heteroscorpionates, specifically, nitro-trispyrazolylborates, in f-element chemistry. They offer great versatility in coordinating ability, donor strength, steric bulk and even optical charge transfer properties, all of which can be used to tune the properties of resultant complexes with metal ions. We show how they can impart structural diversity, sensitize Ln3+ luminescence and engender magnetic anisotropy and slow magnetic relaxation in the ion they coordinate. Additionally, we comment on the future of functionalized trispyrazolyl scorpionates, which includes enabling post-synthetic modifications of f-element complexes and becoming a platform to study the electronic properties of low oxidation state actinides.

Chiral metal-organic cages decorated with binaphthalene moieties

The construction of chiral nanoobjects with atomically precise nanostructures has attracted much more attention in the past decades. However, this field is still in its early stages. We designed and synthesized a series of chiral ligands containing the binaphthalene moiety and isophthalate module. Then, four chiral metal-organic cages (MOCs) were obtained through the coordination between isophthalate modules and copper ions. These chiral MOCs exhibit discrete, uniform and stable structures, good solubility and photoluminescence behaviors.

A Highly Luminescent Metallo-Supramolecular Radical Cage

Luminescent metal-radicals have recently received increasing attention due to their unique properties and promising applications in materials science. However, the luminescence of metal-radicals tends to be quenched after formation of metallo-complexes. It is challenging to construct metal-radicals with highly luminescent properties. Herein, we report a highly luminescent metallo-supramolecular radical cage (LMRC) constructed by the assembly of a tritopic terpyridinyl ligand RL with tris(2,4,6-trichlorophenyl)methyl (TTM) radical and Zn2+. Electrospray ionization-mass spectrometry (ESI-MS), traveling-wave ion mobility-mass spectrometry (TWIM-MS), X-ray crystallography, electron paramagnetic resonance (EPR) spectroscopy, and superconducting quantum interference device (SQUID) confirm the formation of a prism-like supramolecular radical cage. LMRC exhibits a remarkable photoluminescence quantum yield (PLQY) of 65%, which is 5 times that of RL; meanwhile, LMRC also shows high photostability. Notably, significant magnetoluminescence can be observed for the high-concentration LMRC (15 wt % doped in PMMA film); however, the magnetoluminescence of 0.1 wt % doped LMRC film vanishes, revealing negligible spin-spin interactions between two radical centers in LMRC.

Imparting structural robustness of metal-organic cages based on oxo-dimolybdenum clusters

A family of robust and stable molybdenum-based metal-organic cages have been obtained based on the [Mo2O2(μ2-O)2]2+ secondary building unit. The resulting cages are decorated with different pyrdine derivatives that impart structural stability, resulting in the structural elucidation of the activated cage with single-crystal diffraction. The chemical robustness of the cage is also demonstrated by the post-synthetic modification of the cage, which allows the exchange of the pyridine derivatives without rupture of the cage.