ChemCatChem最新文献

Piezoelectric materials offer great promise due to their ability to generate electric fields under mechanical stress, producing surface charges that drive otherwise kinetically sluggish redox reactions. The strained surfaces of these materials provide a unique advantage in controlling product selectivity and enabling reaction pathways that are unattainable with conventional methods. This perspective highlights advancements, challenges, and the future potential of piezoelectric materials in synthetic organic chemistry, with a focus on designing materials optimized for piezocatalyzed organic synthesis. Piezocatalysis is industrially relevant because of its operational simplicity, enabling mild, gram scale synthesis with reusable catalysts, minimal solvent use, and air tolerant conditions. It involves redox cycles that facilitate one electron redox events without requiring light exposure or electrical bias. Despite significant progress, many fundamental aspects are yet to be fully understood. One example is the correlation between piezoelectricity and catalytic activity, which is not always linear, as demonstrated by the comparison between tetragonal and cubic BaTiO₃. While cubic BaTiO₃ is not piezoelectric, it shows excellent catalytic activity in certain redox reactions such as arylation, dicarbonylation, and cyclization under mechanochemical conditions comparable to that of piezoelectric tetragonal BaTiO₃. Considering all these aspects, this perspective aims to stimulate discussion to advance this promising field in the right direction.

The Cover Feature shows the creation of carbon dots (CDs) with multivalent amine ligands represented by the glowing core with a hairy surface. These CDs catalyze the denitrosylation of S-nitrosothiols, enabling the controlled release of nitric oxide (NO) under physiological conditions. Nucleophilic reaction by the primary amine groups drives the NO generation. Integration of these active CDs into a hydrogel-based prototissue allows biological NO-releasing platforms with future biomedical applications to be constructed. More information can be found in the Research Article by S. Rana and co-workers (DOI: 10.1002/cctc.202401338).

The depletion of fossil fuel reserves, coupled with the mounting environmental concerns, highlights the urgent need to develop sustainable methods for chemical synthesis from renewable resources. One promising avenue is the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), utilizing non-precious metal catalysts. Herein, we designed and synthesized covalent organic frameworks (COFs) as electrocatalysts, engineered through the integration of N-hydroxyphthalimide (NHPI) linkers with porphyrin building blocks. Electrochemical studies revealed that the Co-Por-COF-NHPI with metallic porphyrin(Co) surpassed the nonmetallic Por-COF-NHPI in conversion, selectivity, and recyclable stability by virtue of the lower onset potentials, higher current densities, and diminished charge transfer resistance. The Co-Por-COF-NHPI achieved remarkable HMF conversion of 95.5% and selectivity to FDCA of 95.6%, attributable to the synergistic effect of porphyrin(Co) and oxidative organocatalytic NHPI sites. Continuous cycling tests further verified its outstanding stability and durability, underscoring the potential of Co-Por-COF-NHPI as an efficient and sustainable catalyst for biomass conversion.

Carbonaceous materials, especially the metal-free carbons, have attracted widespread attention owing to their risk-free nature with metal dissolving during the electrocatalysis process, but their further developments are still hindered by missing a suitable scenario on practical applications. Herein, we demonstrate a successful case of using the oxygen-containing-groups-modified carbons for the H₂O₂ electrosynthesis and the derivative electrochemical advanced oxidation process. The active sites with the more C─O rather than C═O groups are easily obtained by controlling the temperature and time in the wet chemical treatment. Identified by theoretical calculations and electrochemical testing, the modified carbons with the highest ratio of C─O/C═O groups exhibit high activity with above 90% H₂O₂ selectivity over the entire potential during 2e-transfer oxygen reduction reaction, attributing to their enlarged charge delocalization. In addition, the corresponding gas diffusion electrodes with the high-speed and high-stability H₂O₂ electrosynthesis (2.78 µg s⁻¹ cm⁻² with the above 80% current efficiency) are applied for the electro-peroxone process on the simulant and practical phenolic wastewater, where the chemical oxygen demand removal reaches above 90%. The long-term operation in the harsh electrochemical environment for over 200 h also confirms its great potential for practical electrochemical applications.

The Front Cover highlights an innovative approach for incorporating lipase into deep eutectic solvents (DES) with silica as a mediator, forming an efficient biocatalytic system. The dynamic interface illustrates the seamless interaction between the biocatalyst and the DES, emphasizing its transformative role in ester synthesis. In their Research Article (DOI: 10.1002/cctc.202401393), A. Chrobok and co-workers investigate how silica facilitates enzyme integration, enhancing stability and activity to enable more sustainable and effective biocatalysis. Art by the team of INMYWORK Studio.

In this work, we report a 2D metal-organic framework with dangling pyridine groups, {[Cd₂(4-tpom)₂(oxdz)₂(H₂O)₂]·4H₂O}_n (1), has been synthesized using a flexible N-donor linker, 4-tpom (tetrakis(4-pyridyloxymethylene)methane), and a bent dicarboxylate, oxdz²⁻(4,4′-(1,3,4-oxadiazole-2,5-diyl)-dibenzoate), to demonstrate its multipurpose as a bifunctional heterogeneous catalyst. Its thermal (up to 332 °C) and chemical stability in water and methanol and at different pH levels (5, 7.4, 9) provides sustainability for any application. Its structural features and properties are well established by elemental analysis, powder X-ray diffraction (PXRD), various spectroscopic/microscopic techniques, and geometry optimization. With unsaturated metal centers as the Lewis acidic sites and uncoordinated nitrogen/oxygen atoms as the Lewis/Bronsted basic sites, a very low catalyst loading (1.5 mol%) of activated 1 is found to be sufficient to catalyze two important C─C bond-forming reactions at room temperature: a) the cyanosilylation reaction converting benzaldehyde to trimethyl silyl ether (100% in 5 h) under solvent-free conditions, and b) the Knoevenagel-intramolecular cyclization reaction for converting salicylaldehyde to coumarin-3-carboxylic acid in methanol (99% in 1 h). Notably, this is the first time the same catalyst has been utilized for these two reactions, demonstrating its multipurpose nature. Furthermore, the spent catalyst is recyclable for multiple cycles, maintaining its structural integrity established via FTIR spectroscopy and PXRD.

Two iron salen complexes, Fe─di─F and Fe─di─Me, have been synthesized by incorporating substituents that possess distinct electronic properties to the phenyl diimine bridge of salen ligands, aiming to enhance the catalytic efficiency. These structural modifications enabled the di-fluoro substituted precatalyst, Fe─di─F, to exhibit a significant improvement in hydroboration of ketones. A diverse range of ketones were selectively hydroborated in the presence of various functional groups, even at minimal catalyst loading. The incorporation of fluorine atoms into the salen ligand proved to be a highly effective approach for boosting the catalytic efficiency of iron salen complexes in hydroboration reactions.

Highly efficient Ni-catalyzed C─N/C─C bond formation from amidines during the [3 + 2 + 1] annulation by primary alcohols alone or by primary alcohols with secondary alcohols/phenyl acetylenes has been successfully accomplished toward scaled synthesis of s-triazine and pyrimidines, respectively. A strongly π-acidic bis-azo NNN-pincer scaffold was successfully introduced for dual functionalization such as augmenting the sustainability of the molecular catalyst by enhancing the metal–ligand integrity and interposing a potent electron-sink chromophore. The high yield synthesis (up to 94%) of poly-azaheterocycles with merely 0.001 mol% catalyst loading demonstrates the potency of azo-anion radical assisted catalysis. A diverse range of primary and secondary alcohols are successfully used as substrates. Furthermore, use of methanol/ethanol as C1/C2 synthon (alkylating agents) enables the formation of challenging imine intermediates from amidines through dehydrogenation under mild conditions. This facilitates the synthesis of wide varieties of s-triazines, and pyrimidines driven by the auto-tandem catalyst. Mechanistic investigations reveal that the formation of C─C and C─N bonds proceed through a metalloradical catalysis (MRC) pathway instead of borrowing hydrogen (BH) method and thereby addresses the challenge of controlling stereoselection. This process is initiated by Ni-catalyzed acceptorless dehydrogenation (AD) of the alcohol substrate, followed by a series of sequential steps, including condensation, aza-Michael addition, cyclization, and subsequent dehydrogenation. The well-defined one-electron reductive response at −0.34 V (versus Fc⁺/Fc) is indicative of the involvement of azo anion radical during catalytic annulation. The formation of the ligand radical intermediate was further substantiated by an electron paramagnetic resonance (EPR) study conducted both in the presence and absence of radical scavengers, specifically 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), and butylated hydroxytoluene (BHT).

The electrochemical reduction of CO₂ (CO₂RR) on copper electrodes in acetonitrile (MeCN) solutions offers a promising route for converting CO₂ into valuable products but competes with the hydrogen evolution reaction (HER). This study systematically explores the impact of varying water content in MeCN on the selectivity and efficiency of CO₂RR and HER. Cyclic voltammetry shows that increasing water content shifts onset potentials and Tafel slopes, indicating changes in reaction mechanisms and rate-determining steps. In dry MeCN, CO₂RR predominates due to high CO₂ solubility and limited proton availability, but as water content increases, HER kinetics improve, eventually dominating the reaction at higher water concentrations. In situ FTIR spectroscopy and molecular dynamics simulations reveal that water preferentially adsorbs onto the copper electrode surface, enhancing stabilization of reaction intermediates and facilitating HER. These findings provide critical insights into optimizing electrochemical systems for selective CO₂ reduction by controlling water content, offering a pathway for improved electrocatalytic performance.

The paint production sector emits both aromatic compounds and oxygenated volatile organic compounds (OVOCs). Supported palladium catalysts have demonstrated effective oxidation performance for each type of VOCs separately; however, the challenge persists in managing the competitive adsorption of different VOCs types on Pd-based catalysts. In this study, we developed a nitrogen-doped carbon (NC)-modified TiO₂-supported catalyst featuring a highly dispersed, cluster-type Pd structure created through in situ pyrolysis method, which offers more catalytic active sites than conventional nanoparticle catalysts. The catalyst's key characteristics, including high noble-metal usage and an ideal Pd⁰/Pd²⁺ ratio, enhance its catalytic performance for multicomponent VOCs oxidation, reaching T_90% values of 167 and 191 °C (at a space velocity of 40,000 mL/(g h)). Furthermore, the NC structure created through in situ pyrolysis technique aids in diminishing the inhibitive adsorption effect of ethyl acetate on o-xylene and improves the catalyst's resistance to water. This research presents a promising approach for the rational design of highly dispersed Pd catalysts that have enhanced water resistance and offers new understanding in managing competitive adsorption for the efficient removal of multicomponent aromatic VOCs and OVOCs in complicated settings.