Large breathing effect in ZIF-65(Zn) with expansion and contraction of the SOD cage

Tailoring Molecular Diffusion in Core-Shell Zeolite Imidazolate Framework Composites Realizes Efficient Kinetic Separation of Xylene Isomers

The separation of xylene isomers is a critical and energy-intensive process in the petrochemical industry, primarily due to their closely similar molecular structures and boiling points. In this work, we report the synthesis and application of a novel core-shell zeolitic imidazolate framework (ZIF) composite, ZIF-65@ZIF-67, designed to significantly enhance the kinetic separation of xylene isomers through a synergistic "shell-gated diffusion and core-facilitated transport" strategy. The external ZIF-67 shell selectively restricts the diffusion of larger isomers (MX and OX), while the internal ZIF-65 core accelerates the diffusion of PX, thereby amplifying the diffusion differences among the isomers. This architecture yields remarkable improvements in both selectivity and diffusion rates, as demonstrated by vapor-phase adsorption studies and molecular dynamics simulations. The ZIF-65@ZIF-67 composite exhibits up to 12.5 times higher PX/OX selectivity in liquid-phase adsorption and 3.4 times higher dynamic selectivity in fixed-column breakthrough experiments compared to the individual ZIF components. Theoretical simulations further corroborate the heterogeneous diffusion control mechanism, revealing the time-dependent diffusion regulation within the core-shell architecture. This work underscores the great potential of core-shell MOF composites in optimizing molecular sieving processes for industrially significant separations and highlights a new route for enhancing kinetic separation efficiency in complex multicomponent systems.

Plastic Pores for Switchable and Optimized Adsorption Behaviors

Similar to conventional solids, porous materials have demonstrated rigid and flexible behaviors. Here, we show that flexible pores can be not just elastic but also plastic. By variation of the hydrogen-bonding ability and steric hindrance of ligand side groups, the energy difference and barrier between metastable states of a porous framework are fine-tuned to enable the plastic behavior. All metastable pore structures can transform to the target ones in atmospheres of the target guests with sufficiently high pressures, and all shaped pores can remain unchanged after guest removal, resulting in optimized host-guest recognitions for the target guests. Up to a 6-fold increase of adsorption selectivity and 9-fold increase of purification productivity for CO2 capture and coalmine CH4 upgrading, and even inversion of CO2/C2H2 selectivity, have been achieved by reversible pore-shaping of a single plastic-pore adsorbent. The realization of plastic pores creates an opportunity for on-demand switching of adsorption and separation functions with optimized performances.

Modeling Gas Adsorption and Mechanistic Insights into Flexibility in Isoreticular Metal-Organic Frameworks Using High-Dimensional Neural Network Potentials

Metal-organic frameworks (MOFs), known for their remarkable porous and well-organized structures, have found extensive use in various applications, including gas storage. Predicting the bulk properties from atomistic simulations as well as gas uptakes and the adsorption mechanism requires the most accurate definition of MOF systems. The application of ab initio molecular dynamics to these extensive periodic systems exceeds the current computational capabilities. Consequently, alternative strategies need to be devised to decrease computational costs without compromising accuracy. In this work, we construct high-dimensional neural network potentials (HDNNPs) to describe rotationally and translationally invariant energies and forces of isoreticular metal-organic framework (IRMOF) series at the density functional theory level of accuracy using a fragmentation technique to study H2 and CH4 adsorption isotherms by means of an "adsorption-relaxation" model in which molecular dynamics and grand canonical Monte Carlo simulations were performed simultaneously. Herein, for the first time, we report that HDNNPs could be utilized for such simulations with excellent agreement with experimental values. We also report that the UFF4MOF force field may not be suitable for adsorption-relaxation simulations. In addition, we show that the real number of CH4 uptake values of IRMOF-10 under the extreme conditions could be much greater than what the classical force field predicts. Adsorption-relaxation simulations enable us to characterize the behavior of MOF atoms and the distribution of gas molecules during the adsorption process, giving the most detailed mechanistic picture.

Pore Structure Modulation in Kirigamic Zeolitic Imidazolate Framework

Paper crafts, such as origami and kirigami, have become an interdisciplinary research theme transportable from art to science, and further to engineering. Kirigami-inspired architectural design strategies allow the establishment of three-dimensional (3D) mechanical linkages with unprecedented mechanical properties. Herein, we report a crystalline zeolitic imidazolate framework (ZIF), displaying folding mechanics based on a kirigami tessellation, originated from the double-corrugation surface (DCS) pattern. Pressure- and guest-induced responses demonstrate the kirigami mechanism of the ZIF, wherein imidazolate linkers act as hinges, controlling pore dimensionality, resembling the check valve-adapted mechanical manifold. This discovery of the kirigami tessellation inside a flexible ZIF reveals foldable mechanics at the molecular level.

Au3+-Functionalized Metal-Organic Framework Coordinated Nanotherapeutics for Substrate Self-Supplied Parallel Catalytic and Calcium-Overload-Mediated Therapy of Cancer

The multiple enzymatic properties of the Au3+-modified metal-organic framework (Au3+-MOFs) have made it a functional catalytic system for antitumor treatment. However, in the face of insufficient catalytic substrates in tumor tissue, it is still impossible to achieve efficient treatment of tumors. Herein, Au3+-MOFs loaded with hyaluronic acid (HA)-modified calcium peroxide nanoparticles (CaO2 NPs) were used to construct a nanozyme (Au3+-MOF/CaO2/HA) for substrate self-supplied and parallel catalytic/calcium-overload-mediated therapy of cancer. Due to the specific targeted ability and retention (EPR) effect of the HA, the built nanozyme can effectively accumulate at the tumor site. Due to the oxidase-like (OXD) activity and peroxidase-like (POD) activity of Au3+-MOFs, superoxide radical anion (O2•-) and hydroxyl radicals (·OH) were cooperatively formed for parallel catalytic therapy (PCT) of cancer. Subsequently, CaO2 NPs were decomposed to Ca2+, H2O2, and O2 in the weak acidic environment of the tumor microenvironment (TME). Thus, self-supplementation of O2 as well as H2O2 was achieved, alleviating the deficiency of Au3+-MOF nanozyme catalytic substrate. In addition, Ca2+ can lead to oxidative stress for tumor calcification and calcium-overload-mediated therapy (COMT) to promote tumor necrosis in vivo. An effective paradigm of tumor PCT/COMT therapy with a self-supplying substrate has been successfully established for considerably enhanced therapeutic efficacy.

Structural Features, Chemical Diversity, and Physical Properties of Microporous Sodalite-Type Materials: A Review

This review contains data on a wide class of microporous materials with frameworks belonging to the sodalite topological type. Various methods for the synthesis of these materials, their structural and crystal chemical features, as well as physical and chemical properties are discussed. Specific properties of sodalite-related materials make it possible to consider they as thermally stable ionic conductors, catalysts and catalyst carriers, sorbents, ion exchangers for water purification, matrices for the immobilization of radionuclides and heavy metals, hydrogen and methane storage, and stabilization of chromophores and phosphors. It has been shown that the diversity of properties of sodalite-type materials is associated with the chemical diversity of their frameworks and extra-framework components, as well as with the high elasticity of the framework.

Template Role of Long Alkyl-Chain Amides in the Synthesis of Zeolitic Imidazolate Frameworks

Organic amides as solvents and structure directing agents (SDAs) are crucial for synthesizing zeolitic imidazolate frameworks (ZIFs). However, current research focuses only on the use of short alkyl-chain amides as solvents/SDAs. Here, we investigate the role of amides with varying alkyl-chain lengths on the structures and topologies of Zn(Im)2 polymorphs. Using short alkyl-chain amides as solvents, the Zn(Im)2 topological structures are affected by the synthesis conditions, leading to "one SDA/multiple topological structures". In contrast, when long alkyl-chain amides are used as solvents, the Zn(Im)2 topological structures are essentially unaffected by other synthesis conditions. Thus, long alkyl-chain amides are shown for the first time to exhibit a significant template role, leading to "one template/one topological structure". Specifically, the use of long alkyl-chain N,N-dimethyl-Cn amides (abbreviated as DM-Cn amides, n = 3, 4, 6, 8, and 10) can lead to only DTF-type Zn(Im)2 frameworks under broad crystallization conditions. Single-crystal X-ray diffraction confirmed that the exquisite structural compatibility between long alkyl-chain DM-Cn amides and the DFT-type Zn(Im)2 framework results in a highly regular head-to-tail arrangement of amides along the (kaa-lov) n chain of the DFT framework. The template role for long alkyl-chain amides was further identified to be multiple C-H···π interactions between DM-Cn amides and Zn(Im)2 frameworks thanks to molecular simulations.

Evolution of the Structure and Morphology of Dual-Linker ZIF-301-eIm

Few studies have reported on the continuous evolution of dual-linker zeolitic imidazolate frameworks' (ZIFs) structure and morphology during the crystal growth process. Herein, we report the synthesis of a novel ZIF material with CHA topology (ZIF-301-eIm) via the combination of a small-sized 2-ethylimidazole (eIm) with the large-sized 5-chlorobenzimidazole ligand. A series of derivative materials with distinct structures and morphologies were obtained via two pathways: (1) insufficient amount of eIm with prolonged crystallization time (pathway A) and (2) sufficient amount of eIm with prolonged crystallization time (pathway B). Various characterization techniques revealed the continuous evolution of structure and morphology during the crystal growth process. Insufficient amount of eIm and crystallization time (crystallization pathway A) led to ZIF-301-eIm derivatives with defective and open structures alongside an aggregated morphology of nanoparticles. Prolonging the crystallization time allowed small-sized eIm ligands to gradually fill into the framework, resulting in the formation of ZIF-301-eIm-A5 characterized by complete but dense structures with a perfect polyhedral morphology. Remarkably, a sufficient amount of eIm during synthesis (crystallization pathway B) formed ZIF-301-eIm-B1 with a similar structure and morphology to ZIF-301-eIm-A5 in just 1 day. ZIF-301-eIm-B3, with intact, dense structures, exhibits superior acetone/butanol separation performance compared to ZIF-301-eIm-A3 due to small pore windows and large cages facilitating selective adsorption of acetone through exclusion separation.

Popping and Locking: Balanced Rigidity and Porosity of Zeolitic Imidazolate Frameworks for High-Productivity Methane Purification

Zeolitic imidazolate frameworks (ZIFs) hold great promise in carbon capture, owing to their structural designability and functional porosity. However, intrinsic linker dynamics limit their pressure-swing adsorption application to biogas upgrading and methane purification. Recently, a functionality-locking strategy has shown feasibility in suppressing such dynamics. Still, a trade-off between structural rigidity and uptake capacity remains a key challenge for optimizing their high-pressure CO2/CH4 separation performance. Here, we report a sequential structural locking (SSL) strategy for enhancing the CO2 capture capacity and CH4 purification productivity in dynamic ZIFs (dynaZIFs). Specifically, we isolated multiple functionality-locked phases, ZIF-78-lt, -ht1, and -ht2, by activation at 50, 160, and 210 °C, respectively. We observed multiple-level locking through gas adsorption and powder X-ray diffraction. We uncovered an SSL mechanism dominated by linker-linker π-π interactions that transit to C-H···O hydrogen bonds with binding energies increasing from -0.64 to -2.77 and -5.72 kcal mol-1, respectively, as evidenced by single-crystal X-ray diffraction and density functional theory calculations. Among them, ZIF-78-ht1 exhibits the highest CO2 capture capacity (up to 18.6 mmol g-1) and CH4 purification productivity (up to 7.6 mmol g-1) at 298 K and 30 bar. These findings provide molecular and energetic insights into leveraging framework flexibility through the SSL mechanism to optimize porous materials' separation performance.

Zeolitic imidazolate framework-8: a versatile nanoplatform for tissue regeneration

Extensive research on zeolitic imidazolate framework (ZIF-8) and its derivatives has highlighted their unique properties in nanomedicine. ZIF-8 exhibits advantages such as pH-responsive dissolution, easy surface functionalization, and efficient drug loading, making it an ideal nanosystem for intelligent drug delivery and phototherapy. These characteristics have sparked significant interest in its potential applications in tissue regeneration, particularly in bone, skin, and nerve regeneration. This review provides a comprehensive assessment of ZIF-8's feasibility in tissue engineering, encompassing material synthesis, performance testing, and the development of multifunctional nanosystems. Furthermore, the latest advancements in the field, as well as potential limitations and future prospects, are discussed. Overall, this review emphasizes the latest developments in ZIF-8 in tissue engineering and highlights the potential of its multifunctional nanoplatforms for effective complex tissue repair.

Polynuclear Rare-Earth Cluster-Directed Self-Assembly of Highly Porous Zeolite-like Metal-Organic Frameworks with Methane Storage Property

Due to their intrinsic structural features, the design and synthesis of a new type of zeolite-like metal-organic frameworks (ZMOFs) is highly desirable but challenging. Herein, solvothermal reactions between an angular dicarboxylate linker and rare-earth (RE) ions afforded two RE-MOFs, namely, Tb-ZMOF-2 and Tb-ZMOF-3, respectively. Structural analyses reveal that Tb-ZMOF-2 encompasses a novel [446482] cage, while Tb-ZMOF-3 contains nonanuclear (i.e., D6R) and hexanuclear (i.e., D4R) RE clusters simultaneously, subsequently resulting in two new zeolitic topologies. Thanks to its high surface area and pore volume, Tb-ZMOF-2 demonstrates considerably high gravimetric and volumetric methane storage working capacities.

Dual-quenching mechanisms in electrochemiluminescence immunoassay based on zinc-based MOFs of ruthenium hybrid for D-dimer detection

The successful application of electrochemiluminescence (ECL) in immunoassay for clinical diagnosis requires improving sensitivity and accuracy. Herein was reported an ECL analytical model based zinc-based metal-organic frameworks of ruthenium hybrid (RuZn MOFs) as the signal emitter. To enlarge the output difference, the quenching effect of three different noble metal nanoparticles included palladium seeds (Pd_seeds), palladium octahedrons (Pd_oct), and Pt-based palladium (Pd@Pt_oct) core-shell were researched. Among them, Pd@Pt_oct core-shell possessed higher activity and improved durability than Pd-only (NPs), they could load more protein macromolecules amicably and stabilized in the analysis system. Furthermore, since the charge redistribution owing to the hybridization of the Pt and Pd atoms in Pd@Pt_oct, it could generate the electron flow maximumly from the emitter RuZn MOFs to Pd@Pt_oct and result in the enhancement of quenching ECL. And the UV absorption of noble metal nanoparticles overlapped with the ECL emission of RuZn MOFs to varying degrees, which caused the behavior of resonance energy transfer (RET) reaction at the same time. This would greatly promote the sensitivity of this ECL system compared with the traditional single quenching mechanism. Based on this, a signal-off immunsensor was constructed to sensitive detection of D-dimer with linearity range from 0.001 to 200 ng mL^-1, limit of detection (LOD) was 0.20 pg mL^-1 and provide a further theoretical basis for the clinical application of ECL technology.