Engineering Donor-Acceptor Arrangement in Perylene Diimide-Based Covalent Organic Frameworks for Enhanced Singlet Oxygen Photocatalysis.

The photocatalytic efficiency of two-dimensional covalent organic frameworks (2D COFs) is governed by the spatial arrangement of donor-acceptor (D-A) moieties, which strongly influences exciton transport. However, precise control over D-A alignment, especially across intra- and interlayer dimensions, remains a key challenge for optimizing singlet oxygen (O) generation. Here, we present a linker geometry-directed approach to modulate D-A organization within perylene diimide (PDI)-based COFs.

2D Covalent Organic Frameworks with cpt-defect topology Enabled by a Node-Splitting Strategy.

Reticular chemistry provides a robust platform for the construction of two-dimensional covalent organic frameworks (2D COFs) with tailored architectures and functionalities. A key synthetic challenge lies in the integration of densely arranged functional moieties without compromising long-range structural order. Herein, we report a node-splitting strategy in which half of the 6-connected -symmetric nodes in the cpt topology are replaced by trios of 2-connected -symmetric nodes, generating a new topology.

Cobalt-Metalated 1D Perylene Diimide Carbon-Organic Framework for Enhanced Photocatalytic α-C(sp)─H Activation and CO Reduction.

The photocatalytic activation of inert C(sp)─H bonds in saturated aza-heterocycles provides a direct and efficient route to high-value α-amino amides but remains challenging due to intrinsically high bond dissociation energies. Herein, we report a cobalt-metalated, one-dimensional ABC-stacking covalent organic framework (PP-COF-Co), integrating perylene diimide (PDI) as a photosensitizer and 1,10-phenanthroline as a metal coordination site. Cobalt metalation significantly enhances photocatalytic efficiency, enabling the α-C(sp)─H carbamoylation of saturated aza-heterocycles with yields of up to 91%, far surpassing its non-metalated counterpart (59%).

Urea-Linked Covalent Organic Framework as a Li-Ion Guided Channel Enabling Ultra-Stable Lithium Metal Anode in Carbonate-Based Electrolyte.

Lithium (Li) metal exhibits great potential for achieving high-energy-density rechargeable batteries. However, the practical application of Li metal anodes is severely hindered by the uncontrollable growth of lithium dendrites as well as the instability of the spontaneously generated solid electrolyte interphase (SEI), causing safety concerns and lifespan issues. Herein, we customize a novel urea-linked covalent organic framework (COF-531) as an interfacial Li-ion guided channel.

Low-valence platinum single atoms in sulfur-containing covalent organic frameworks for photocatalytic hydrogen evolution.

This study focuses on optimizing catalytic activity in photocatalytic hydrogen evolution reaction by precisely designing and modulating the electronic structure of metal single atoms. The catalyst, denoted as PtSA@S-TFPT, integrates low-valence platinum single atoms into sulfur-containing covalent organic frameworks. The robust asymmetric four-coordination between sulfur and platinum within the framework enables a high platinum loading of 12.

Linkage Engineering in Covalent Organic Frameworks for Metal-Free Electrocatalytic CH Production from CO.

Electrocatalytic carbon dioxide reduction reaction (CORR) to produce ethylene (CH) is conducive to sustainable development of energy and environment. At present, most electrocatalysts for CH production are limited to the heavy metal copper, meanwhile, achieving metal-free catalysis remains a challenge. Noted piperazine with sp N hybridization is beneficial to CO capture, but CORR performance and mechanism have been lacking.

Nitrogen-Rich Conjugated Microporous Polymers with Improved Cobalt(II) Density for Highly Efficient Electrocatalytic Oxygen Evolution.

Developing efficient oxygen evolution catalysts (OECs) made from earth-abundant elements is extremely important since the oxygen evolution reaction (OER) with sluggish kinetics hinders the development of many energy-related electrochemical devices. Herein, an efficient strategy is developed to prepare conjugated microporous polymers (CMPs) with abundant and uniform coordination sites by coupling the N-rich organic monomer 2,4,6-tris(5-bromopyrimidin-2-yl)-1,3,5-triazine (TBPT) with Co(II) porphyrin. The resulting CMP-Py(Co) is further metallized with Co ions to obtain CMP-Py(Co)@Co.

Thiol-Ene Click Reaction Modified Triazinyl-Based Covalent Organic Framework for Pb(II) Ion Effective Removal.

As a common water pollutant, Pb has harmful effects on the nervous, hematopoietic, digestive, renal, cardiovascular, and endocrine systems. Due to the drawbacks of traditional adsorbents such as structural disorder, poor stability, and difficulty in introducing adsorption active sites, the adsorption capacity is low, and it is difficult to accurately study the adsorption mechanism. Herein, vinyl-functionalized covalent organic frameworks (COFs) were synthesized at room temperature, and sulfur-containing active groups were introduced by the click reaction.

Revolutionizing the structural design and determination of covalent-organic frameworks: principles, methods, and techniques.

Covalent organic frameworks (COFs) represent an important class of crystalline porous materials with designable structures and functions. The interconnected organic monomers, featuring pre-designed symmetries and connectivities, dictate the structures of COFs, endowing them with high thermal and chemical stability, large surface area, and tunable micropores. Furthermore, by utilizing pre-functionalization or post-synthetic functionalization strategies, COFs can acquire multifunctionalities, leading to their versatile applications in gas separation/storage, catalysis, and optoelectronic devices.

Recent Progress on Phase Engineering of Nanomaterials.

As a key structural parameter, phase depicts the arrangement of atoms in materials. Normally, a nanomaterial exists in its thermodynamically stable crystal phase. With the development of nanotechnology, nanomaterials with unconventional crystal phases, which rarely exist in their bulk counterparts, or amorphous phase have been prepared using carefully controlled reaction conditions.

Kagome-topology 2D covalent organic frameworks assembled from -symmetric and non-centrosymmetric -symmetric blocks for photothermal imaging.

In this study, we synthesized two new two-dimensional (2D) covalent organic frameworks (COFs), COF-TA and COF-DP, by combining 4-connected -symmetric and 2-connected non-centrosymmetric -symmetric building blocks. Unlike the typical sql topology, these COFs exhibit an unconventional topology characterized by a favorable anti-parallel stacking arrangement, which results in a lower energy configuration. Notably, COF-DP, with its unique D-A-D structural motif and photosensitive properties, demonstrates a narrow band gap and excellent photothermal conversion capabilities, making it a promising material for photothermal imaging applications.

Salt-Assisted Fabrication of a Water-Based Covalent Organic Framework Ink and Its Hybrid Films for Photothermal Actuators.

The exceptional properties of two-dimensional covalent organic framework materials (2D-COFs), including their large π-conjugated structure at the molecular level and π-π multilayer stacking, have attracted interest for soft photothermal actuator applications. However, the conventional synthesis of COFs as microcrystalline powders limits their processing in water due to their limited dispersibility. Herein, we present a simple and environmentally friendly method to fabricate water-suspended COF inks by adjusting the surface potential of COF powders through adsorption of ionic species such as Na and Cl.

A rigidity-flexibility balance strategy enabling highly photoluminescent two-dimensional covalent organic framework nanosheets.

The fluorescence quenching phenomenon commonly found in two-dimensional COFs is due to either the strong interlayer π-π stacking or the non-radiative decay caused by intramolecular rotation. Here, we report a rigidity-flexibility balance strategy for constructing highly photoluminescent 2D COF nanosheets the integration of rigid fluorescent molecular nodes with flexible non-planar building blocks. The prepared COF nanosheets, termed TPE-DBC-COF, achieve extremely high PLQY in common organic solvents, especially in tetrahydrofuran (43.

Synthesis and Visualization of Entangled 3D Covalent Organic Frameworks with High-Valency Stereoscopic Molecular Nodes for Gas Separation.

The structural diversity of three-dimensional (3D) covalent organic frameworks (COFs) are limited as there are only a few choices of building units with multiple symmetrically distributed connection sites. To date, 4 and 6-connected stereoscopic nodes with T , D , D and C symmetries have been mostly reported, delivering limited 3D topologies. We propose an efficient approach to expand the 3D COF repertoire by introducing a high-valency quadrangular prism (D ) stereoscopic node with a connectivity of eight, based on which two isoreticular 3D imine-linked COFs can be created.

Substoichiometric 3D Covalent Organic Frameworks Based on Hexagonal Linkers.

Covalent organic frameworks (COFs), a fast-growing field in crystalline porous materials, have achieved tremendous success in structure development and application exploration over the past decade. The vast majority of COFs reported to date are designed according to the basic concept of reticular chemistry, which is rooted in the idea that building blocks are fully connected within the frameworks. We demonstrate here that sub-stoichiometric construction of 2D/3D COFs can be accomplished by the condensation of a hexagonal linker with 4-connected building units.