Dual-Enzyme-Mimicking Sites in Covalent Organic Frameworks Enable Highly Efficient Relay Electrosynthesis of Ammonia.

Electrocatalytic nitrate reduction poses significant importance in green ammonia synthesis and water denitrification. To date, high-performance nitrate reduction still relies on noble-metal-based catalysts, while transition metal compound and framework catalysts generally suffer from low activities (in terms of turnover frequency values), leading to insufficient ability to rapidly process large amounts of nitrate at the industrial level. To this end, enzyme-mimicking catalytic systems that integrate the high TOF efficiency of enzymatic sites (typically with nonprecious metal centers) into the crystalline, orderly assembled, and porous molecular frameworks hold great theoretical promises, yet the search for any single enzyme-site mimics has failed to overcome current limitations.

Square-Planar Tetranuclear Cluster-Based High-Symmetry Coordination Metal-Organic Polymers for Efficient Electrochemical Nitrate Reduction to Ammonia.

Metal-organic polymers (MOPs) are gaining booming attention as atomically precise single-site catalysts for electrochemical nitrate-to-ammonia conversion owing to their regular structures and tunable functionalities. However, a molecular-level understanding is still lacking for the design of more efficient MOP electrocatalysts. Here, we report the construction of high-symmetry coordination MOPs (, , and ), utilizing square-planar tetranuclear building units [M(μ-O)(CO)] (M = Mn, Fe, or Co) bridged by 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (HTATB) ligands.

Multivariate Tuning of Photosensitization in Mixed-Linker Metal-Organic Frameworks for Efficient CO Reduction.

Photosensitization is a powerful approach for enhancing the photocatalyst performance by improving light absorption, energy transfer, and charge separation. However, achieving high efficiency requires precise control over photosensitizers, catalytic centers, and their interactions, which remain challenging in heterogeneous systems. Herein, we develop multivariate zirconium metal-organic frameworks (MOFs) with mixing linkers and tunable defects that enable unprecedented control over photosensitizers, catalytic centers, and their ratios, creating an efficient platform for CO reduction.

Efficient Ammonia Electrosynthesis from Pure Nitrate Reduction via Tuning Bimetallic Sites in Redox-Active Covalent Organic Frameworks.

Electrocatalytic nitrate reduction reaction (NITRR) represents a promising approach for ammonia synthesis, but existing application has been constrained by the complex proton-coupled electron transfer and the sluggish kinetics induced by various intermediates. Herein, we synthesized a series of metalized covalent organic frameworks: NiTP-MTAPP MCOFs (M = 2H, Co, Cu, and Fe), based on dual redox-active centers: thiophene-substituted Ni-bis(dithiolene) ligand-Ni[CS(CHSCHO)] and metallic porphyrin. Through regulating the adsorption and desorption of species at the catalytic sites, we have identified the optimal NITRR electrocatalyst: NiTP-CoTAPP MCOF, which achieved the highest faradaic efficiency (FE) of approximately 85.

Self-Photosensitizing Cobalt Complexes for Photocatalytic CO Reduction Coupled with CHOH Oxidation.

The use of metal complexes as homogeneous molecular catalysts has attracted considerable attention regarding photocatalytic CO reduction. Enhancing these complexes with photosensitivity and photooxidation capabilities, aiming to create multifunctional molecular devices, presents significant challenges. In response to these challenges, we successfully designed and synthesized three innovative metal complexes.

Ligand spin immobilization in metal-organic frameworks enables high-performance chemispintronic detection of radical gas molecules.

The precise quantification of gaseous radicals in exhaled breath, such as fractional exhaled nitric oxide, serves as an invaluable noninvasive clinical diagnosis particularly in discerning various respiratory disorders. To date, the development of high-performance nitric oxide sensors compatible to modern electronic devices remains fundamentally challenging. We report that metal-organic frameworks (MOFs) with ligand spin immobilization demonstrate superior chemispintronic sensitivity and selectivity toward nitric oxide.

An Efficient Ultra-Narrowband Yellow Emitter Based on a Double-Boron-Embedded Tetraazacyclophane.

Ultra-narrowband and highly modifiable multiple resonance thermally activated delayed fluorescence (MR-TADF) materials are crucial for realizing high-performance wide-color-gamut display applications. Despite progress, most MR-TADF emitters remain confined to blue and green wavelengths, with difficulties extending into longer wavelengths without significant spectral broadening, which compromises color purity in full-color organic light-emitting diode (OLED) displays. In this work, we present a novel tetraazacyclophane-based architecture embedding dual boron atoms to remarkedly enhance intramolecular charge transfer through the strategic positioning of boron and nitrogen atoms.

Solubility-Limited Small Molecule for Stable High-Capacity Potassium Storage.

Small molecule electrode materials with superb redox activity have significant applied implications for K-ion storage, but they face significant challenges like high solubility in electrolytes and low conductivity, limiting their capacity, rate, and cycling stability. Herein, a series of Ni-bis(dithiolene) (NiS)-based small molecules are designed with control of various redox-active substitutional groups for K-ion batteries anode materials. It is identified that bis[1,2-di(pyridine-4-yl) ethylene-1,2-dithiolate] nickel Ni[CSPy] demonstrates a high reversible specific capacity (399 mAh g at 0.

Integrating Multiple Redox-Active Units into Conductive Covalent Organic Frameworks for High-Performance Sodium-Ion Batteries.

The rational design of porous covalent organic frameworks (COFs) with high conductivity and reversible redox activity is the key to improving their performance in sodium-ion batteries (SIBs). Herein, we report a series of COFs (FPDC-TPA-COF, FPDC-TPB-COF, and FPDC-TPT-COF) based on an organosulfur linker, (trioxocyclohexane-triylidene)tris(dithiole-diylylidene))hexabenzaldehyde (FPDC). These COFs feature two-dimensional crystalline structures, high porosity, good conductivity, and densely packed redox-active sites, making them suitable for energy storage devices.

Polynuclear Cobalt Cluster-Based Coordination Polymers for Efficient Nitrate-to-Ammonia Electroreduction.

The electrocatalytic nitrate reduction reaction (NITRR) holds great promise for purifying wastewater and producing valuable ammonia (NH). However, the lack of efficient electrocatalysts has impeded the achievement of highly selective NH synthesis from the NITRR. In this study, we report the design and synthesis of two polynuclear Co-cluster-based coordination polymers, {[Co(TCPPDA)(HO)]·(HO)(DMF)} and {Co(TCPPDA)[(CH)NH]·(HO)(DMF)} (namely, and ), which possess distinct coordination motifs with well-defined porosity, high-density catalytic sites, accessible mass transfer channels, and nanoconfined chemical environments.

Porous Crystalline Materials Based on Tetrathiafulvalene and Its Analogues: Assembly, Charge Transfer, and Applications.

ConspectusThe directed synthesis and functionalization of porous crystalline materials pose significant challenges for chemists. The synergistic integration of different functionalities within an ordered molecular material holds great significance for expanding its applications as functional materials. The presence of coordination bonds connected by inorganic and organic components in molecular materials can not only increase the structural diversity of materials but also modulate the electronic structure and band gap, which further regulates the physical and chemical properties of molecular materials.

Dynamic Interchain Motion in 1D Tetrathiafulvalene-Based Coordination Polymers for Highly Sensitive Molecular Recognition.

The application of electrically conductive 1D coordination polymers (1D CPs) in nanoelectronic molecular recognition is theoretically promising yet rarely explored due to the challenges in their synthesis and optimization of electrical properties. In this regard, two tetrathiafulvalene-based 1D CPs, namely [Co(m-HTTFTB)(DMF)(HO)] (Co-m-TTFTB), and {[Ni(m-HTTFTB)(CHCHOH)(HO)]·(HO)} (Ni-m-TTFTB) are successfully constructed. The shorter S···S contacts between the [M(solvent)(m-HTTFTB)] chains contribute to a significant improvement in their electrical conductivities.

Tetraborated Intrinsically Axial Chiral Multi-resonance Thermally Activated Delayed Fluorescence Materials.

Chiral multi-resonance thermally activated delayed fluorescence (CP-MR-TADF) materials hold promise for circularly polarized organic light-emitting diodes (CP-OLEDs) and 3D displays. Herein, we present two pairs of tetraborated intrinsically axial CP-MR-TADF materials, R/S-BDBF-BOH and R/S-BDBT-BOH, with conjugation-extended bidibenzo[b,d]furan and bidibenzo[b,d]thiophene as chiral sources, which effectively participate in the distribution of the frontier molecular orbitals. Due to the heavy-atom effect, sulfur atoms are introduced to accelerate the reverse intersystem crossing process and increase the efficiency of molecules.

Construction of a stable radical hydrogen-bonded metal-organic framework with functionalized tetrathiafulvalene linkers.

A stable two-dimensional radical hydrogen-bonded metal-organic framework, constructed using a modified tetrathiafulvalene-tetrabenzoate ((2-Me)-HTTFTB) linker and Cd ions, exhibits a high electrical conductivity of 4.1 × 10 S m and excellent photothermal conversion with a temperature increase of 137 °C in 15 s under the irradiation of a 0.7 W cm 808 nm laser.

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.

Metal-Coordinated Covalent Organic Frameworks as Advanced Bifunctional Hosts for Both Sulfur Cathodes and Lithium Anodes in Lithium-Sulfur Batteries.

The shuttling of polysulfides on the cathode and the uncontrollable growth of lithium dendrites on the anode have restricted the practical application of lithium-sulfur (Li-S) batteries. In this study, a metal-coordinated 3D covalent organic framework (COF) with a homogeneous distribution of nickel-bis(dithiolene) and N-rich triazine centers (namely, NiS-TAPT) was designed and synthesized, which can serve as bifunctional hosts for both sulfur cathodes and lithium anodes in Li-S batteries. The abundant Ni centers and N-sites in NiS-TAPT can greatly enhance the adsorption and conversion of the polysulfides.

Accessible Tetrathiafulvalene Moieties in a 3D Covalent Organic Framework for Enhanced Near-Infrared Photo-Thermal Conversion and Photo-Electrical Response.

Redox-active tetrathiafulvalene (TTF)-based covalent organic frameworks (COFs) exhibit distinctive electrochemical and photoelectrical properties, but their prevalent two-dimensional (2D) structure with densely packed TTF moieties limits the accessibility of redox center and constrains their potential applications. To overcome this challenge, an 8-connected TTF linker (TTF-8CHO) is designed as a new building block for the construction of three-dimensional (3D) COFs. This approach led to the successful synthesis of a 3D COF with the bcu topology, designated as TTF-8CHO-COF.

Coordination-Modulated Metal Tetrathiafulvalene Octacarboxylate Frameworks for High-Performance Lithium-Ion Battery Anodes.

Modulation of the ligands and coordination environment of metal-organic frameworks (MOFs) has been an effective and relatively unexplored avenue for improving the anode performance of lithium-ion batteries (LIBs). In this study, three MOFs are synthesized, namely, M (o-TTFOB)(bpm) (H O) (where M is Mn, Zn, and Cd; o-H TTFOB is ortho-tetrathiafulvalene octabenzoate; and bpm is 2,2'-bipyrimidine), based on a new ligand o-H TTFOB with two adjacent carboxylates on one phenyl, which allows us to establish the impact of metal coordination on the performance of these MOFs as anode materials in LIBs. Mn-o-TTFOB and Zn-o-TTFOB, with two more uncoordinated oxygen atoms from o-TTFOB , show higher reversible specific capacities of 1249 mAh g and 1288 mAh g under 200 mA g after full activation.

Dynamic Bond-Directed Synthesis of Stable Mesoporous Metal-Organic Frameworks under Room Temperature.

Stable metal-organic frameworks (MOFs) with mesopores (2-50 nm) are promising platforms for immobilizing nanosized functional compounds, such as metal-oxo clusters, metal-sulfide quantum dots, and coordination complexes. However, these species easily decompose under acidic conditions or high temperatures, hindering their encapsulation in stable MOFs, which are usually synthesized under harsh conditions involving excess acid modulators and high temperatures. Herein, we report a route for the room-temperature and acid-modulator-free synthesis of stable mesoporous MOFs and MOF catalysts with acid-sensitive species encapsulated: (1) we initially construct a MOF template by connecting stable Zr clusters with labile Cu-bipyridyl moieties; (2) Cu-bipyridyl moieties are subsequently exchanged by organic linkers to afford a stable version of Zr-MOFs; (3) acid-sensitive species, including polyoxometalates (POMs), CdSeS/ZnS quantum dots, and Cu-coordination cages, can be encapsulated into the MOFs during step 1.

Integrating Tetrathiafulvalene and Nickel-Bis(dithiolene) Units into Donor-Acceptor Covalent Organic Frameworks for Stable and Efficient Photothermal Conversion.

Tetrathiafulvalene (TTF) and Ni-bis(dithiolene) are typical conductive units widely studied in electronics, optics, and photochemistry. However, their applications in near-infrared (NIR) photothermal conversion are often limited by insufficient NIR absorption and low chemical/thermal stability. Herein, we integrate TTF and Ni-bis(dithiolene) into a covalent organic framework (COF) with stable and efficient NIR and solar photothermal conversion performance.

Tough, Reprocessable, and Recyclable Dynamic Covalent Polymers with Ultrastable Long-Lived Room-Temperature Phosphorescence.

Room-temperature phosphorescence (RTP) polymers, whose emission can persist for a long period after photoexcitation, are of great importance for practical applications. Herein, dynamic covalent boronic ester linkages with internal B-N coordination are incorporated into a commercial epoxy matrix. The reversible dissociation of B-N bonds upon loading provides an efficient energy dissipation pathway for the epoxy network, while the rigid epoxy matrix can inhibit the quenching of triplet excitons in boronic esters.