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Conventional strategies for highly efficient and selective CO2 photoreduction focus on the design of catalysts and cocatalysts. In this study, we discover that hydrogen bond network breakdown in reaction system can suppress H2 evolution, thereby improving CO2 photoreduction performance. Photosensitive poly(ionic liquid)s are designed as photocatalysts owing to their strong hydrogen bonding with solvents. The hydrogen bond strength is tuned by solvent composition, thereby effectively regulating H2 evolution (from 0 to 12.6 mmol g−1 h−1). No H2 is detected after hydrogen bond network breakdown with trichloromethane or tetrachloromethane as additives. CO production rate and selectivity increase to 35.4 mmol g−1 h−1 and 98.9 % with trichloromethane, compared with 0.6 mmol g−1 h−1 and 26.2 %, respectively, without trichloromethane. Raman spectroscopy and theoretical calculations confirm that trichloromethane broke the systemic hydrogen bond network and subsequently suppressed H2 evolution. This hydrogen bond network breakdown strategy may be extended to other catalytic reactions involving H2 evolution. [ABSTRACT FROM AUTHOR]

Nucleophilic substitutions are fundamentally important transformations in synthetic organic chemistry. Despite the substantial advances in bimolecular nucleophilic substitutions (SN2) at saturated carbon centers, analogous SN2 reaction at the amide nitrogen atom remains extremely limited. Here we report an SN2 substitution method at the amide nitrogen atom with amine nucleophiles for nitrogen–nitrogen (N−N) bond formation that leads to a novel strategy toward biologically and medicinally important hydrazide derivatives. We found the use of sulfonate‐leaving groups at the amide nitrogen atom played a pivotal role in the reaction. This new N−N coupling reaction allows the use of O‐tosyl hydroxamates as electrophiles and readily available amines, including acyclic aliphatic amines and saturated N‐heterocycles as nucleophiles. The reaction features mild conditions, broad substrate scope (>80 examples), excellent functional group tolerability, and scalability. The method is applicable to late‐stage modification of various approved drug molecules, thus enabling complex hydrazide scaffold synthesis. [ABSTRACT FROM AUTHOR]

One‐step separation of C2H4 from ternary C2 mixtures by physisorbents remains a challenge to combine excellent separation performance with high stability, low cost, and easy scalability for industrial applications. Herein, we report a strategy of constructing negative electrostatic pore environments in a stable, low‐cost, and easily scaled‐up aluminum MOF (MOF‐303) for efficient one‐step C2H2/C2H6/C2H4 separation. This material exhibits not only record high C2H2 and C2H6 uptakes, but also top‐tier C2H2/C2H4 and C2H6/C2H4 selectivities at ambient conditions. Theoretical calculations combined with in situ infrared spectroscopy indicate that multiple N/O sites on pore channels can build a negative electro‐environment to provide stronger interactions with C2H2 and C2H6 over C2H4. Breakthrough experiments confirm its exceptional separation performance for ternary mixtures, affording one of the highest C2H4 productivity of 1.35 mmol g−1. This material is highly stable and can be easily synthesized at kilogram‐scale from cheap raw materials using a water‐based green synthesis. The benchmark combination of excellent separation properties with high stability and low cost in scalable MOF‐303 has unlocked its great potential in this challenging industrial separation. [ABSTRACT FROM AUTHOR]

Developing hydrogen‐bonded organic frameworks (HOFs) that combine functional sites, size control, and storage capability for targeting gas molecule capture is a novel and challenging venture. However, there is a lack of effective strategies to tune the hydrogen‐bonded network to achieve high‐performance HOFs. Here, a series of HOFs termed as HOF‐ZSTU‐M (M=1, 2, and 3) with different pore structures are obtained by introducing structure‐directing agents (SDAs) into the hydrogen‐bonding network of tetrakis (4‐carboxyphenyl) porphyrin (TCPP). These HOFs have distinct space configurations with pore channels ranging from discrete to continuous multi‐dimensional. Single‐crystal X‐ray diffraction (SCXRD) analysis reveals a rare diversity of hydrogen‐bonding models dominated by SDAs. HOF‐ZSTU‐2, which forms a strong layered hydrogen‐bonding network with ammonium (NH4+) through multiple carboxyl groups, has a suitable 1D "pearl‐chain" channel for the selective capture of propylene (C3H6). At 298 K and 1 bar, the C3H6 storage density of HOF‐ZSTU‐2 reaches 0.6 kg L−1, representing one of the best C3H6 storage materials, while offering a propylene/propane (C3H6/C3H8) selectivity of 12.2. Theoretical calculations and in situ SCXRD provide a detailed analysis of the binding strength of C3H6 at different locations in the pearl‐chain channel. Dynamic breakthrough tests confirm that HOF‐ZSTU‐2 can effectively separate C3H6 from multi‐mixtures. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) with expanding porosity and tailored pore environments are intriguing for catalytic applications. We report herein a straightforward method of controlled partial linker thermolysis to introduce desirable mesopores into mono‐ligand MOFs, which is different from the classical thermolyzing method that starts from mixed‐linker MOFs. UiO‐66‐NH2, after partial ligand thermolysis, exhibits significant mesoporosity, retained crystal structure, improved charge photogeneration and abundant anchoring sites, which is ideal to explore single‐site photocatalysis. Atomically dispersed Cu is then accommodated in the tailored pore. The resulting single‐site Cu catalyst exhibits excellent performance for photocatalytic alkylation and oxidation coupling for the functionalization of terminal alkynes. The study highlights the advantage of controlled partial linker thermolysis to synthesize hierarchical MOFs to achieve the advanced single‐site photocatalysis. [ABSTRACT FROM AUTHOR]

Integrating a molecular catalyst with a light harvester into a photocatalyst is an effective strategy for solar light conversion. However, it is challenging to establish a crystallized framework with well‐organized connections that favour charge separation and transfer. Herein, we report the heterogenization of a Salen metal complex molecular catalyst into a rigid covalent organic framework (COF) through covalent linkage with the light‐harvesting unit of pyrene for photocatalytic hydrogen evolution. The chemically conjugated bonds between the two units contribute to fast photogenerated electron transfer and thereby promote the proton reduction reaction. The Salen cobalt‐based COF showed the best hydrogen evolution activity (1378 μmol g−1 h−1), which is superior to the previously reported nonnoble metal based COF photocatalysts. This work provides a strategy to construct atom‐efficient photocatalysts by the heterogenization of molecular catalysts into covalent organic frameworks. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of nitrate pollutants to ammonia has emerged as an attractive alternative for ammonia synthesis. Currently, many strategies have been developed for enhancing nitrate reduction to ammonia (NRA) efficiency, but the influence of the degree of structural disorder is still unexplored. Here, carbon‐supported RuO2 nanosheets with adjustable crystallinity are synthesized by a facile molten salt method. The as‐synthesized amorphous RuO2 displays high ammonia Faradaic efficiency (97.46 %) and selectivity (96.42 %), greatly outperforming the crystalline counterparts. The disordered structure with abundant oxygen vacancies is revealed to modulate the d‐band center and hydrogen affinity, thus lowering the energy of the potential‐determining step (NH2*→NH3*). [ABSTRACT FROM AUTHOR]

A recent research article published in Angewandte Chemie discusses the breakdown of the hydrogen bond network in the CO2 photoreduction system, which can suppress the evolution of H2 and increase the production of CO. The study by Chengcheng Liu, Weiqiao Deng, and others focuses on the use of photosensitive poly(ionic liquid)s as photocatalysts, which have strong hydrogen bonding with solvents. By disrupting the hydrogen bond network with solvent additives, the researchers were able to effectively suppress H2 evolution in photocatalytic CO2 reduction. Another research article in the journal discusses the use of metal-organic frameworks to achieve photocatalytic CO2 reduction to syngas. [Extracted from the article]

Synthesis of functional 3D COFs with irreversible bond is challenging. Herein, 3D imide‐bonded COFs were constructed via the imidization reaction between phthalocyanine‐based tetraanhydride and 1,3,5,7‐tetra(4‐aminophenyl)adamantine. These two 3D COFs are made up of interpenetrated pts networks according to powder X‐ray diffraction and gas adsorption analyses. CoPc‐PI‐COF‐3 doped with carbon black has been employed to fabricate the electrocatalytic cathode towards CO2 reduction reaction within KHCO3 aqueous solution, displaying the Faradaic efficiency of 88–96 % for the CO2‐to‐CO conversion at the voltage range of ca. −0.60 to −1.00 V (vs. RHE). In particular, the 3D porous structure of CoPc‐PI‐COF‐3 enables the active electrocatalytic centers occupying 32.7 % of total cobalt‐phthalocyanine subunits, thus giving a large current density (jCO) of −31.7 mA cm−2 at −0.90 V. These two parameters are significantly improved than the excellent 2D COF analogue (CoPc‐PI‐COF‐1, 5.1 % and −21.2 mA cm−2). [ABSTRACT FROM AUTHOR]

Fundamental understanding of the dependence between the structure and composition on the electrochemical CO2 reduction reaction (CO2RR) would guide the rational design of highly efficient and selective electrocatalysts. A major impediment to the deep reduction CO2 to multi‐carbon products is the complexity of carbon–carbon bond coupling. The chemically well‐defined catalysts with atomically dispersed dual‐metal sites are required for these C−C coupling involved processes. Here, we developed a catalyst (BIF‐102NSs) that features Cl− bridged dimer copper (Cu2) units, which delivers high catalytic activity and selectivity for C2H4. Mechanistic investigation verifies that neighboring Cu monomers not only perform as regulator for varying the reaction barrier, but also afford distinct reaction paths compared with isolated monomers, resulting in greatly improved electroreduction performance for CO2. [ABSTRACT FROM AUTHOR]

A robust 2,2′‐bipyridine (bpy)‐derived biological hydrogen‐bonded framework (HOF‐25) has been realized depending on guanine‐quadruplex with the assistance of π‐π interaction, which reacts with Re(CO)5Cl to give a post‐functionalized HOF‐25‐Re. X‐ray absorption fine structure spectroscopic study on HOF‐25‐Re confirms the covalent attachment of Re(bpy)(CO)3Cl segments to this HOF. Robust and recycled HOF‐25‐Re bearing photocatalytic Re(bpy)(CO)3Cl centers displays good heterogeneous catalytic activity towards carbon dioxide photoreduction in the presence of [Ru(bpy)3]Cl2 and triisopropanolamine in CH3CN under visible‐light irradiation, with both high CO production rate of 1448 μmol g−1 h−1 and high selectivity of 93 %. Under the same conditions, the experimental turnover number of HOF‐25‐Re (50) is about 8 times as that of the homogeneous control Re(bpy)(CO)3Cl. The sustainably regenerated HOF‐25‐Re via crystallization and post‐modification processes shows recovered photocatalytic performance. [ABSTRACT FROM AUTHOR]