Two Analogous Polyhedron-Based MOFs with High Density of Lewis Basic Sites and Open Metal Sites: Significant CO2 Capture and Gas Selectivity Performance

Stoichiometry-Regulated Synthesis of Three Adenine-Based Coordination Polymers for Catalytic Excellence through the Synergistic Amalgamation of Coordinative Unsaturation and Lewis Basic Sites

Nucleobase adenine is a promising candidate for synthesizing fascinating coordination polymers (CPs) due to the presence of five potential metal-ion binding centers. In recent years, CPs have emerged as promising Lewis acid-base centers containing heterogeneous catalysts for a wide range of organic transformations. However, the crucial role of stoichiometric regulations of the starting materials and their consequential impact on catalytic performance are rarely studied. Herein, we have synthesized three adenine (Ad)-based cadmium CPs with 5-nitro isophthalic acid (H2NIPA) by a mixed linker approach by tuning the substrate's stoichiometric proportion. The single-crystal X-ray diffraction analysis of the synthesized CPs, SSICG-11, [Cd(Ad)(NIPA)(H2O)]·H2O; SSICG-12, [Cd(Ad)2(NIPA)(H2O)]; and SSICG-13, [Cd4(Ad)(NIPA)3]·H2O·DMF, reveals that these three compounds exhibit distinct asymmetric units, each reflecting varying precursor proportions. Due to their high chemical stability and the presence of both Lewis acidic-basic sites, SSICG-11-13 were employed as heterogeneous catalysts for Hantzsch and Strecker reactions. However, SSICG-12 is more efficient due to its capacity to form an open metal sites (OMSs) and the presence of a higher number of adenine moieties. Overall, this study demonstrated the stoichiometrically controlled synthesis of adenine-based CPs and dissected their efficiency as a heterogeneous catalyst by correlating their structures and compositions.

Three Polyhedron-Based Metal-Organic Frameworks Exhibiting Excellent Acetylene Selective Adsorption

The separation of acetylene (C2H2) from ethylene (C2H4) and ethane (C2H6) is crucial for the production of high-purity C2H2 and the recovery of other gases. Polyhedron-based metal-organic frameworks (PMOFs) are characterized by their spacious cavities, which facilitate gas trapping, and cage windows with varying sizes that enable gas screening. In this study, we carefully selected a class of PMOFs based on V-type tetracarboxylic acid linker (JLU-Liu22 containing benzene ring, JLU-Liu46 containing urea group and recombinant reconstructed In/Cu CBDA on the basis of JLU-Liu46) to study the relationship between pore environment and C2 adsorption and separation performance. Among the three compounds, JLU-Liu46 exhibits superior selectivity toward C2H2/C2H4 (2.06) as well as C2H2/C2H6 (2.43). Comparative structural analysis reveals that the exceptional adsorbed-C2H2 performance of JLU-Liu46 can be attributed to the synergistic effects arising from coordinatively unsaturated Cu sites combined with an optimal pore environment (matched pore size and polarity, urea functional group), resulting in a strong affinity between the framework and C2H2 molecules. Furthermore, transient breakthrough simulations of JLU-Liu46 confirmed its potential for separating C2H2 in ternary C2 gas.

Cd(II)-based complex loaded with drug doxorubicin hydrogels against leukemia and reinforcement learning

A new 3D metal-organic frameworks [Cd6(L)4(bipy)3(H2O)2·H2O] (1) was gained by employing Cd(II) and organic ligand [H3L = 4,4',4''-(benzene-1,3,5-triyltris(oxy))tribenzoic acid)benzene acid; bipy = 4,4'-bipyridine] in the solvothermal condition, which has been fully examined via single-X ray diffraction, FTIR and elemental analysis and so on. Using natural polysaccharides hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) as raw materials, we successfully prepared HA/CMCS hydrogels and observed their internal micromorphology by scanning electron microscopy. Using doxorubicin (Dox) as a drug model, we synthesized a novel metal gel particle loaded with doxorubicin, and their encapsulation and release effects were studied using fluorescence spectroscopy, followed by further investigation of their components through thermogravimetric analysis. Based on this, the therapeutic effect on leukemia was evaluated. Finally, an enhanced learning method for automatically designing new ligand structures from host ligands was proposed. Through generative modeling and molecular docking simulations, the biological behavior of the host and predicted cadmium complexes was extensively studied.

Efficient CO2 Capture and Separation in MOFs: Effect from Isoreticular Double Interpenetration

Severe CO2 emissions has posed an increasingly alarming threat, motivating the development of efficient CO2 capture materials, one of the key parts of carbon capture, utilization, and storage (CCUS). In this study, a series of metal-organic frameworks (MOFs) named Sc-X (X = S, M, L) were constructed inspired by recorded MOFs, Zn-BPZ-SA and MFU-4l-Li. The corresponding isoreticular double-interpenetrating MOFs (Sc-X-IDI) were subsequently constructed via the introduction of isoreticular double interpenetration. Grand canonical Monte Carlo (GCMC) simulations were adopted at 298 K and 0.1-1.0 bar to comprehensively evaluate the CO2 capture and separation performances in Sc-X and Sc-X-IDI, with gas distribution, isothermal adsorption heat (Qst), and van der Waals (vdW)/Coulomb interactions. It is showed that isoreticular double interpenetration significantly improved the interactions between adsorbed gases and frameworks by precisely modulating pore sizes, particularly observed in Sc-M and Sc-M-IDI. Specifically, the Qst and Coulomb interactions exhibited a substantial increase, rising from 28.38 and 22.19 kJ mol-1 in Sc-M to 43.52 and 38.04 kJ mol-1 in Sc-M-IDI, respectively, at 298 K and 1.0 bar. Besides, the selectivity of CO2 over CH4/N2 was enhanced from 55.36/107.28 in Sc-M to 3308.61/7021.48 in Sc-M-IDI. However, the CO2 capture capacity is significantly influenced by the pore size. Sc-M, with a favorable pore size, exhibits the highest capture capacity of 15.86 mmol g-1 at 298 K and 1.0 bar. This study elucidated the impact of isoreticular double interpenetration on the CO2 capture performance in MOFs.

Enhanced CO2 capture in partially interpenetrated MOFs: Synergistic effects from functional group, pore size, and steric-hindrance

Excessive CO2 emissions have contributed to global environmental issues, driving the development of CO2 capture adsorbents. Among various candidates, metal-organic frameworks (MOFs) are considered the most promising due to their unique microporous structure. Herein, a series of partially interpenetrated MOFs named UPC-XX were built to investigate the continuous enhancement in CO2 capture performance via synergistic effects from functional group, pore size, and steric-hindrance using theoretical calculations. It's showed that the introduction of functional groups improved the structure polarity and created more adsorption sites, thus, enhanced CO2 capture capacity. The pore size modification augments the exposure of adsorption sites to mitigate the negative impact of pore space and surface area reduction caused by the introduction of functional groups, thereby further increasing the CO2 capture capacity. The steric-hindrance effect optimized the adsorption sites distribution, which hasn't been considered in the previous two regulation strategies, thus, further increased the CO2 capture capacity. The results underscore UPC-MOFs as outstanding adsorbent materials, among the UPC-MOFs, UPC-OSO3-steric exhibited the highest CO2 capture capacity of 12.69 mmol/g with selectivities of 1142.41 (CO2 over N2) and 507.42 (CO2 over CH4) at 1.0 bar, 298 K. And the synergistic effect mechanisms of functional group, structure size, and steric hindrance were elucidated through theoretical calculations analyzing pore characteristics, gas distribution, isosteric heat, and van der Waals/Coulomb interactions.

Bioinspired Framework Catalysts: From Enzyme Immobilization to Biomimetic Catalysis

Enzymatic catalysis has fueled considerable interest from chemists due to its high efficiency and selectivity. However, the structural complexity and vulnerability hamper the application potentials of enzymes. Driven by the practical demand for chemical conversion, there is a long-sought quest for bioinspired catalysts reproducing and even surpassing the functions of natural enzymes. As nanoporous materials with high surface areas and crystallinity, metal-organic frameworks (MOFs) represent an exquisite case of how natural enzymes and their active sites are integrated into porous solids, affording bioinspired heterogeneous catalysts with superior stability and customizable structures. In this review, we comprehensively summarize the advances of bioinspired MOFs for catalysis, discuss the design principle of various MOF-based catalysts, such as MOF-enzyme composites and MOFs embedded with active sites, and explore the utility of these catalysts in different reactions. The advantages of MOFs as enzyme mimetics are also highlighted, including confinement, templating effects, and functionality, in comparison with homogeneous supramolecular catalysts. A perspective is provided to discuss potential solutions addressing current challenges in MOF catalysis.

Significantly Enhanced Carbon Dioxide Selective Adsorption via Gradual Acylamide Truncation in MOFs: Experimental and Theoretical Research

A gradual amide truncation strategy was presented to tune the pore chemistry and CO2 capture performance of a series of tetracarboxylate-based Cu-MOFs. These MOFs exhibited a high density of Lewis basic sites (LBSs) and open metal sites and were prepared with the goal to enhance CO2 selective adsorption capacity. [Cu2(L1)(H2O)2]n (NJU-Bai42: NJU-Bai for Nanjing University Bai's group), [Cu2(L2) (H2O)2]n (NJU-Bai17), and [Cu2(L3)(H2O)2]n (NTUniv-60: NTUniv for Nantong University) were synthesized, and we observed that the CO2 adsorption capacities and MOF structures were impacted by subtle changes in ligands. Interestingly, although the NTUniv-60 was decorated with the least LBSs in these three MOFs, its CO2 adsorption capacity reached 270 (53.0 wt %) and 164 (32.2 wt %) cm3 g-1 at 273 and 296 K under 1 bar, respectively, which is the highest data reported for MOFs under similar conditions. From the grand canonical Monte Carlo (GCMC) simulation, the cooperative interactions between the CO2 molecules within the shuttle-shaped cages of NTUniv-60 could potentially explain why the CO2 uptake is high in this material.

Emerging Trends in Sustainable CO2 -Management Materials

With the rising level of atmospheric CO₂ worsening climate change, a promising global movement toward carbon neutrality is forming. Sustainable CO₂ management based on carbon capture and utilization (CCU) has garnered considerable interest due to its critical role in resolving emission-control and energy-supply challenges. Here, a comprehensive review is presented that summarizes the state-of-the-art progress in developing promising materials for sustainable CO₂ management in terms of not only capture, catalytic conversion (thermochemistry, electrochemistry, photochemistry, and possible combinations), and direct utilization, but also emerging integrated capture and in situ conversion as well as artificial-intelligence-driven smart material study. In particular, insights that span multiple scopes of material research are offered, ranging from mechanistic comprehension of reactions, rational design and precise manipulation of key materials (e.g., carbon nanomaterials, metal-organic frameworks, covalent organic frameworks, zeolites, ionic liquids), to industrial implementation. This review concludes with a summary and new perspectives, especially from multiple aspects of society, which summarizes major difficulties and future potential for implementing advanced materials and technologies in sustainable CO₂ management. This work may serve as a guideline and road map for developing CCU material systems, benefiting both scientists and engineers working in this growing and potentially game-changing area.

Defect Engineering of Nanoscale Hf-Based Metal-Organic Frameworks for Highly Efficient Iodine Capture

With the rapid development of the nuclear industry, how to deal with radioactive iodine waste in a timely and effective manner has become an important issue to be solved urgently. Herein, the defect-engineering strategy has been applied to develop a metal-organic framework (MOF)-based solid adsorbent by using the classical UiO-type Hf-UiO-66 as an example. After simple acid treatment, the produced defect-containing Hf-UiO-66 (DHUN) not only retains its topological structure, high crystallization, and regular shape but also shows a great increase in the Brunauer-Emmett-Teller value and pore size in comparison with the original Hf-UiO (HUN). These formed defects within DHUN have been demonstrated to be important for the great enhancement of the iodine capture and following application in computed tomography imaging in vitro. This present work gives a new insight into the control and formation of defect sites, and this simple and efficient defect-engineering strategy also shows great promise for the development of novel solid adsorbents and other functional MOF materials.

Recent Progress on Microfine Design of Metal-Organic Frameworks: Structure Regulation and Gas Sorption and Separation

Metal-organic frameworks (MOFs) have emerged as an important and unique class of functional crystalline hybrid porous materials in the past two decades. Due to their modular structures and adjustable pore system, such distinctive materials have exhibited remarkable prospects in key applications pertaining to adsorption such as gas storage, gas and liquid separations, and trace impurity removal. Evidently, gaining a better understanding of the structure-property relationship offers great potential for the enhancement of a given associated MOF property either by structural adjustments via isoreticular chemistry or by the design and construction of new MOF structures via the practice of reticular chemistry. Correspondingly, the application of isoreticular chemistry paves the way for the microfine design and structure regulation of presented MOFs. Explicitly, the microfine tuning is mainly based on known MOF platforms, focusing on the modification and/or functionalization of a precise part of the MOF structure or pore system, thus providing an effective approach to produce richer pore systems with enhanced performances from a limited number of MOF platforms. Here, the latest progress in this field is highlighted by emphasizing the differences and connections between various methods. Finally, the challenges together with prospects are also discussed.

Rational Stepwise Construction of Different Heterometallic-Organic Frameworks (HMOFs) for Highly Efficient CO2 Conversion

The coordination preference of different metal ions and ligands have an immense influence on the constructions of functional MOF materials. In this work, two new monometallic complexes, namely [Ag(HL)(bipy)_0.5 ] (1) and {[Tb(L)_1.5 (H₂ O)]⋅4 H₂ O}_n (2) (bipy=4,4-bipyridine), have been synthesized successfully by employing a bifunctional 2-(imidazol-1-yl)terephthalic acid (H₂ L) ligand. After that, two new different heterometallic-organic frameworks (HMOFs), namely {[TbAg(L)₂ (H₂ O)₃ ]⋅H₂ O}_n (3) and [TbAg(L)₂ (H₂ O)]_n (4), were obtained from complexes 1 and 2 as the precursors based on a rational stepwise construction strategy and the theory of hard and soft acids and bases (HSAB principle), respectively. The HMOFs bearing dual metallic catalytic sites (Tb and Ag) can be used as heterogeneous catalysts without losing performance for the chemical fixation of CO₂ with epoxides including the sterically hindered epoxides, demonstrating some of the highest reported catalytic activity values. This work may provide a new synthetic route toward tailoring new HMOFs with excellent catalytic activity.

Highly Selective Separation of C3H8 and C2H2 from CH4 within Two Water-Stable Zn5 Cluster-Based Metal-Organic Frameworks

Adopting the mixed ligands approach, two water-stable Zn₅ cluster-based MOFs, [Zn₁₀(TZ)₁₂(TADIPA)₂(DMF)₄]·DMF·6H₂O (JLU-MOF66) and [Zn₁₀(TZ)₁₂(TPTA)₂(DMA)₂]·2DMA·4H₂O (JLU-MOF67), have been constructed (H₄TADIPA = 5,5'-(1H-1,2,4-triazole-3,5-diyl)diisophthalic acid, H₄TPTA = [1,1':3',1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid, and HTZ = 1H-[1,2,3]triazole). Both compounds with [Zn₅(TZ)₆] clusters exhibit extraordinary stability (pH = 2-11) and selectivity of C₃H₈/CH₄ (308 for JLU-MOF66, and 287 for JLU-MOF67). Compared to JLU-MOF67, JLU-MOF66 with functional groups exhibits higher CO₂ and C₂H₂ uptake capacity and excellent selective separation for C₂H₂/CH₄ (86, 1:1). Such high separation and chemical stability render them as promising materials for industrial applications.

Emerging trends in porous materials for CO2 capture and conversion

This review highlights the recent progress in porous materials (MOFs, zeolites, POPs, nanoporous carbons, and mesoporous materials) for CO₂ capture and conversion.

Highly efficient synergistic CO2 conversion with epoxide using copper polyhedron-based MOFs with Lewis acid and base sites

The catalytic performances and effect of LASs and LBSs of four isomorphous Cu-PMOFs in CO₂ cycloaddition reaction were systematically studied. JLU-Liu21 exhibited significant catalytic efficiency, remarkable recyclability and catalytic stability.

Metal-Assembled, Resorcin[4]arene-Based Molecular Trimer for Efficient Removal of Toxic Dichromate Pollutants and Knoevenagel Condensation Reaction

Self-assembly of resorcin[4]arene-based coordination cages involving more than two resorcin[4]arenes poses significant challenges for the requirements of suitable functionalized resorcin[4]arene ligands and metals. Here, we report an unusual example of a metal-coordinated, resorcin[4]arene-based molecular trimer (1-NO₃), composed of three resorcin[4]arenes and three Cd(II) cations. In particular, 1-NO₃ features efficient and selective removal of environmentally toxic dichromate (Cr₂O₇^2-) anions. Moreover, the Knoevenagel condensation reaction was also explored by using 1-NO₃ as an efficient heterogeneous catalyst.

Two ultramicroporous metal-organic frameworks assembled from binuclear secondary building units for highly selective CO2/N2 separation

Two novel metal-organic frameworks [Ni₂(μ₂-Cl)(BTBA)₂·DMF]·Cl·3DMF (JLU-MOF56, BTBA = 3,5-bis(triazol-1-yl)benzoic acid) and [Co₂(μ₂-Cl)(BTBA)₂·DMF]·Cl·3DMF (JLU-MOF57) have been successfully synthesized under solvothermal conditions. Crystallographic analysis indicates that the two compounds with different metal ions are isoreticular and both are constructed from binuclear [M₂(μ₂-Cl)(COO)₂N₄] (M = Co, Ni) and a 3-connected hetero-N,O donor ligand. The overall framework possesses a (3,6)-connected dag topology. Furthermore, both of them feature ultramicroporous channels of 3.5 Å× 3.4 Å, which are suitable for adsorbing smaller carbon dioxide (CO₂) gas molecules but not larger nitrogen (N₂) gas molecules. Therefore, JLU-MOF56 and JLU-MOF57 exhibit good performance for CO₂/N₂ separation, and are promising materials for gas adsorption and purification.

Multifunctional drug carrier on the basis of 3d–4f Fe/La-MOFs for drug delivery and dual-mode imaging

Multifunctional drug carriers for simultaneous imaging and drug delivery have emerged as an important new direction for the treatment of cancer.

A Zn(ii) metal–organic framework constructed by a mixed-ligand strategy for CO2 capture and gas separation

A microporous Zn(ii) metal–organic framework has been assembled using a mixed-ligand strategy, and it exhibits high capture ability for CO₂ and good selectivity for CO₂/CH₄, C₂H₆/CH₄ and C₃H₈/CH₄.

A heterometallic metal–organic framework based on multi-nuclear clusters exhibiting high stability and selective gas adsorption

Porous In/Tb-CBDA has been successfully synthesized in the light of the heterometallic cooperative crystallization (HCC) approach. In/Tb-CBDA with high thermal and chemical stability exhibited high performance for gas storage and separation.

Robust multivariate metal–porphyrin frameworks for efficient ambient fixation of CO2 to cyclic carbonates

A series of robust polyfluorometalate-metalloporphyrin nets have three-types of orderly distributed metals, high CO₂-trapping capacity and good catalytic properties for coupling CO₂ with epoxides.

Mesoporous Hexanuclear Copper Cluster-Based Metal-Organic Framework with Highly Selective Adsorption of Gas and Organic Dye Molecules

Despite many advances in the design and assembly of mesoporous metal-organic frameworks (meso-MOFs), it is still a challenge to obtain the desired structure. Here, we utilized an effective cluster cooperative assembly strategy by introducing SO₄^2- ions as chelating binding sites to construct a novel mesoporous MOF, [Cu₈(SO₄)(TBA)₆(OH)₂( N,N-dimethylacetamide (DMA))₄]·12DMA·12CH₃OH [JLU-MOF51, H₂TBA = 4-(1 H-tetrazol-5-yl)-benzoic acid]. Remarkably, the cooperative assembly of the infrequent hexanuclear [Cu₆SO₄(OH)₂] cluster and the classical paddlewheel [Cu₂(CO₂)₄] via linear hetero-N, O donor ligand results in an open three-dimensional framework, which possesses one-dimensional nanometer tube channels with the diameter of 24 and 28 Å. Fascinatingly, JLU-MOF51 displays an exceptionally large Langmuir surface area (5443 m² g^-1) and exhibits a high capacity for selective adsorption of C₃H₈ (C₃H₈: 348 cm³ g^-1 at 273 K; C₃H₈/CH₄ = 220 at 298 K). In addition, JLU-MOF51 can selectively adsorb fluorescein disodium salt dye among numerous organic dyes. An extremely high surface area and unique structural characteristics make JLU-MOF51 a promising meso-MOF material for the adsorption and separation of hydrocarbon gases and organic dyes. Moreover, this strategy will provide an effective means for constructing meso-MOFs via one-step synthesis.

Highly Effective Removal of Nonsteroidal Anti-inflammatory Pharmaceuticals from Water by Zr(IV)-Based Metal-Organic Framework: Adsorption Performance and Mechanisms

Nonsteroidal anti-inflammatory pharmaceuticals are emerging organic micropollutants in surface water, groundwater, and wastewater, whose removal is very important yet challenging. As a new class of porous functional materials, metal-organic frameworks (MOFs) have attracted extensive attention for their adsorption applications. Here, we report that Zr(IV)-based MOFs (defective UiO-66, and MOF-808) have extraordinary adsorption ability to remove nonsteroidal anti-inflammatory pharmaceuticals from water. Excellent adsorption performances are obtained for UiO-66 and MOF-808, particularly for UiO-66, of which the adsorption capacities are the highest in a wide series of adsorptive materials previously reported. It is elucidated that the incomplete-coordinated cationic Zr in the cluster has high affinity for the anionic pharmaceutical (chemical adsorption) and that the adsorption interaction between the benzene ring of the pharmaceutical and MOF's ligand is involved to enhance or as an alternative to the adsorption interactions (π-π interaction). In particular, adsorption of ibuprofen, ketoprofen, naproxen, indomethacin, and furosemide by UiO-66 and MOF-808 and the synergetic effect of chemical adsorption and π-π interaction are outstanding, leading to extremely higher binding energies ( E_bind) and sorption abilities.

An anionic metal–organic framework: metathesis of zinc(ii) with copper(ii) for efficient C3/C2 hydrocarbon and organic dye separation

Efficient separation of C₃/C₂ hydrocarbon and organic dyes is achieved on an anionic copper–organic framework formed by metal metathesis.