From fundamentals to applications: a toolbox for robust and multifunctional MOF materials

Highly Selective and Reversible Sulfur Dioxide Adsorption on a Microporous Metal-Organic Framework via Polar Sites

It is very challenging to achieve efficient and deep desulfurization, especially in flue gases with an extremely low SO₂ concentration. Herein, we report a microporous metal-organic framework (ELM-12) with specific polar sites and proper pore size for the highly efficient SO₂ removal from flue gas and other SO₂-containing gases. A high SO₂ capacity of 61.2 cm³·g^-1 combined with exceptionally outstanding selectivity of SO₂/CO₂ (30), SO₂/CH₄ (871), and SO₂/N₂ (4064) under ambient conditions (i.e., 10:90 mixture at 298 K and 1 bar) was achieved. Notably, the SO₂/N₂ selectivity is unprecedented among ever reported values of porous materials. Moreover, the dispersion-corrected density functional theory calculations illustrated the superior SO₂ capture ability and selectivity arise from the high-density SO₂ binding sites of the CF₃SO₃^- group in the pore cavity (S^δ+···O^δ- interactions) and aromatic linkers in the pore walls (H^δ+···O^δ- interactions). Dynamic breakthrough experiments confirm the regeneration stability and excellent separation performance. Furthermore, ELM-12 is also stable after exposure to SO₂, water vapor, and organic solvents.

Dihalobenzene Shape Sorting by Nonporous Adaptive Crystals of Perbromoethylated Pillararenes

The separation of dihalobenzene isomers, such as dichlorobenzene isomers and difluorobenzene isomers, has a high practical value in both synthetic chemistry and industrial production. Herein we provide a simple to operate and energy-efficient adsorptive separation method using nonporous adaptive crystals of perbromoethylated pillar[5]arene (BrP5) and pillar[6]arene (BrP6). BrP6 crystals show a preference towards the ortho isomer of dichlorobenzene in isomer mixtures, but cannot discriminate difluorobenzene isomers. Single-crystal structures reveal that this selectivity is derived from the stability of the new host-guest crystal structure of BrP6 after uptake of the preferred guest and the binding strength of the host-guest interactions. Furthermore, because of the reversible transition between guest-free and guest-loaded structures, BrP6 crystals are recyclable.

Nanoscale ATP-Responsive Zeolitic Imidazole Framework-90 as a General Platform for Cytosolic Protein Delivery and Genome Editing

Metal-organic frameworks (MOFs) are an emerging class of nanocarriers for drug delivery, owing to their tunable chemical functionality. Here we report ATP-responsive zeolitic imidazole framework-90 (ZIF-90) as a general platform for cytosolic protein delivery and CRISPR/Cas9 genome editing. The self-assembly of imidazole-2-carboxaldehyde and Zn²⁺ with protein forms ZIF-90/protein nanoparticles and efficiently encapsulates protein. It was found that, in the presence of ATP, the ZIF-90/protein nanoparticles are degraded to release protein due to the competitive coordination between ATP and the Zn²⁺ of ZIF-90. Intracellular delivery studies showed that the ZIF-90/protein nanoparticle can deliver a large variety of proteins into the cytosol, regardless of protein size and molecular weight. The delivery of cytotoxic RNase A efficiently prohibits tumor cell growth, while the effective delivery of genome-editing protein Cas9 knocks out the green fluorescent protein (GFP) expression of HeLa cells with efficiency up to 35%. Given the fact that ATP is upregulated in disease cells, it is envisaged that the ATP-responsive protein delivery will open up new opportunities for an advanced protein delivery and CRISPR/Cas9 genome editing for targeted disease treatment.

Versatile carboxylate-directed structures of ten 1D → 3D Ni(ii) coordination polymers: fluorescence behaviors and electrochemical activities

Ten 1D → 3D Ni(ii) coordination polymers based on a phenyl/methylene-mixed-bridged ligand have been obtained and structurally directed by carboxylates; they show different fluorescence behaviors and electrochemical activities.

Hydrothermal generation, structural versatility and properties of metal(ii)-organic architectures driven by a pyridine-tricarboxylic acid

A new series of metal(ii) coordination compounds driven by a pyridine-tricarboxylate block was generated, their structural features, magnetic, luminescent or photocatalytic properties were explored.

Fabrication of hierarchically porous MIL-88-NH2(Fe): a highly efficient catalyst for the chemical fixation of CO2 under ambient pressure

A hierarchically micro- and mesoporous MIL-88-NH₂ metal organic framework was prepared through an easy template directed methodology.

Carbon capture and conversion using metal–organic frameworks and MOF-based materials

This review summarizes recent advances and highlights the structure–property relationship on metal–organic framework-based materials for carbon dioxide capture and conversion.

High quantum yield pure blue emission and fast proton conduction from an indium–metal–organic framework

A 3D anionic In³⁺–MOF integrates the multifunctionality of pure blue luminescence with a high quantum yield of 61.4% and water-mediated fast proton conduction with σ = 2.90–9.22 × 10⁻³ S cm⁻¹ at 25–60 °C and 99% RH.

Ab initio powder X-ray diffraction structural analysis of bispidine based 1D coordination polymers: insights into their guest responsive behaviour

The first ab initio synchrotron powder XRD structure solution of a desolvated 1D bispidine coordination polymer (CP) is reported, providing valuable insights into the stability, dynamic and guest responsive behavior of a new class of CPs.

The chemistry of multi-component and hierarchical framework compounds

This review is expected to provide a library of multi-component hierarchically porous compounds, which shall guide the state-of-the-art design of future porous materials with unprecedented tunability, synergism and precision.

A 3D heterometallic Ni(ii)/K(i) MOF with a rare rna topology: synthesis, structural features, and photocatalytic dye degradation modeling

A new picolinate-driven Ni/K MOF was prepared by different methods, fully characterized, and explored in the photocatalytic degradation of bromocresol green.

Visible-light-mediated guest trapping in a photosensitizing porous coordination network: metal-free C–C bond-forming modification of metal–organic frameworks for aqueous-phase herbicide adsorption

Metal-free visible-light-mediated C–C bond-forming modification of metal–organic frameworks (MOFs) for aqueous-phase herbicide adsorption.

A tri-functional metal–organic framework heterogeneous catalyst for efficient conversion of CO2 under mild and co-catalyst free conditions

A novel tri-functional MOF catalyst was achieved by PSM method. Because of the synergistic effect of Lewis acid, Brønsted acid and Br⁻ anion, MIL-IMAc-Br⁻ displayed an efficient catalytic performance for CO₂ conversion.

A series of dysprosium-based hydrogen-bonded organic frameworks (Dy–HOFs): thermally triggered off → on conversion of a single-ion magnet

A series of dysprosium-based HOFs (Dy–HOFs) were designed and synthesized for the first time under solvothermal conditions. Herein, we achieved the magnetic off → on SIM switching of Dy–HOFs under thermal driving conditions.

[Zr6O4(OH)4(benzene-1,4-dicarboxylato)6]n: a hexagonal polymorph of UiO-66

The first polymorph of the paradigmatic UiO-66 and the key conditions that led to its formation are reported.

Uncovering Two Principles of Multivariate Hierarchical Metal-Organic Framework Synthesis via Retrosynthetic Design

Multivariate (MTV) hierarchical metal-organic frameworks (MOFs), which contain multiple regions arranged in ordered structures, show promise for applications such as gas separation, size-selective catalysis, and controlled drug delivery. However, the complexity of these hierarchical MOFs is limited by a lack of control during framework assembly. Herein, we report the controlled generation of hierarchical MOF-on-MOF structural formation under the guidance of two design principles, surface functionalization and retrosynthetic techniques for stability control. Accordingly, the tunability of spatial distributions, compositions, and crystal sizes has been achieved in these hierarchical systems. The resulting MOF-on-MOF hierarchical structures represent a unique crystalline porous material which contains a controllable distribution of functional groups and metal clusters that are associated together within a framework composite. This general synthetic approach not only expands the scope and tunability of the traditional MTV strategy to multicomponent materials, but also offers a facile route to introduce variants and sequences to sophisticated three-dimensional hierarchical and cooperative systems. As a proof of concept, the photothermal effects of a porphyrinic core-MOF are exploited to trigger the controlled guest release from a shell-MOF with high guest capacity, highlighting the integrated cooperative behaviors in multivariate hierarchical systems.

Colloidal Metal-Organic Framework Hexapods Prepared from Postsynthesis Etching with Enhanced Catalytic Activity and Rollable Packing

Recent studies on the effect of particle shapes have led to extensive applications of anisotropic colloids as complex materials building blocks. Although much research has been devoted to colloids of convex polyhedral shapes, branched colloids remain largely underexplored because of limited synthesis strategies. Here we achieved the preparation of metal-organic framework (MOF) colloids in a hexapod shape, not directly from growth but from postsynthesis etching of truncated rhombic dodecahedron (TRD) parent particles. To understand the branch development, we used in situ optical microscopy to track the local surface curvature evolution of the colloids as well as facet-dependent etching rate. The hexapods show unique properties, such as improved catalytic activity in a model Knoevenagel reaction likely due to enhanced access to active sites, and the assembly into open structures which can be easily integrated with a self-rolled-up nanomembrane structure. Both the postsynthesis etching and the hexapod colloids demonstrated here show a new route of engineering micrometer-sized building blocks with exotic shapes and intrinsic functionalities originated from the molecular structure of materials.