Catalytic Strategy Research Articles

Highly Efficient Degradation of 2-Methylisoborneol by Laccase Assisted by a Micro-Electric Field

Taste and odor (T&O) compounds have emerged as crucial parameters for assessing water quality. Therefore, identifying effective methodologies for the removal of these compounds is imperative. In this study, an effective approach utilizing laccase assisted by a micro-electric field was developed for the degradation of 2-methylisoborneol (2-MIB). For this purpose, the optimal conditions for the laccase-catalyzed degradation of 2-MIB were determined, and they were pH 4.0, 25 °C, 150 rpm, 0.1 U/mL of laccase, and 200 ng/L of 2-MIB. Under these specified conditions, the degradation efficiency of 2-MIB was approximately 78% after a 4 h reaction period. Subsequently, the introduction of an electric field yielded a synergistic effect with the enzyme for 2-MIB degradation. At an electric current intensity of 0.04 A over a 4 h duration, the degradation efficiency increased to 90.78%. An analysis using SPME-GC/MS provided information on the degradation intermediates of 2-MIB resulting from laccase-catalyzed degradation, electrocatalytic degradation, and micro-electric-assisted laccase degradation. The potential degradation pathways of 2-MIB illustrated that these three methods result in common degradation products, such as capric aldehyde, nonylaldehyde, and 2-ethylhexanol, and their final products include 3-pentanone, acetone, and 2-butanone. This study provides an enzyme–electrochemical method for the efficient and rapid degradation and removal of 2-MIB. The strategy of laccase catalysis assisted by a micro-electric field has good potential for the removal of pollutants from the natural environment.

Photoredox/NHC Dual Catalysis Enabled de Novo Synthesis of α-Amino Acids Derivatives.

Herein, we report a mild and operationally simple photoredox/NHC dual catalysis strategy for the α-carboxylation of tertiary amine C(sp3)-H bonds using diethyl pyrocarbonate. This method offers a novel approach for synthesizing α-amino acid derivatives. The protocol features a broad substrate scope, accommodating both N-aryl tetrahydroisoquinolines (THIQ) and N-methyl aniline and is scalable to gram quantities. Additionally, it is suitable for the late-stage derivatization of certain pharmaceutical compounds.

Reductive catalytic fractionation of cotton stalks: catalytic strategy for tuning the selectivity of phenolic monomers

Reductive catalytic fractionation of cotton stalks: catalytic strategy for tuning the selectivity of phenolic monomers

Anchoring Catalytic Metal Nodes within a Single-Crystalline Pyrazolate Metal-Organic Framework for Efficient Heterogeneous Catalysis.

The synthesis of single-crystalline and robust pyrazolate metal-organic frameworks (Pz-MOFs) capable of facilitating challenging organic transformations is fundamentally significant in catalysis. Here we demonstrate a metal-node-based catalytic site anchoring strategy by synthesizing a single-crystalline and robust Pz-MOF (PCN-1004). PCN-1004 features one-dimensional (1D) copper-Pz chains interconnected by well-organized ligands, forming a porous three-dimensional (3D) network with two types of 1D open channels. Notably, PCN-1004 displays exceptional stability in aqueous solutions across a broad pH range (1 to 14), attributed to the robust copper-Pz coordination bonds. Significantly, PCN-1004 functions as an outstanding catalyst in cross dehydrogenative coupling reactions for constructing C-O/C-S bonds, even in the absence of directing groups, achieving yields of up to ~99%, with long cycle lives and high substrate compatibility. PCN-1004 outperforms all previously reported porphyrin-based homogeneous and heterogeneous catalysts. Control experiments and computations elucidate the pivotal catalytic role of the copper-Pz chains and reveal a free radical pathway for the reaction. This work not only demonstrates the successful implementation of a metal-node-based catalytic site anchoring strategy for the efficient catalysis of challenging organic transformations but also highlights the synergistic effect of a robust framework, 1D open channels, and active sites in enhancing catalytic efficiency within MOFs.

Anchoring Catalytic Metal Nodes within a Single‐Crystalline Pyrazolate Metal‐Organic Framework for Efficient Heterogeneous Catalysis

The synthesis of single‐crystalline and robust pyrazolate metal‐organic frameworks (Pz‐MOFs) capable of facilitating challenging organic transformations is fundamentally significant in catalysis. Here we demonstrate a metal‐node‐based catalytic site anchoring strategy by synthesizing a single‐crystalline and robust Pz‐MOF (PCN‐1004). PCN‐1004 features one‐dimensional (1D) copper‐Pz chains interconnected by well‐organized ligands, forming a porous three‐dimensional (3D) network with two types of 1D open channels. Notably, PCN‐1004 displays exceptional stability in aqueous solutions across a broad pH range (1 to 14), attributed to the robust copper‐Pz coordination bonds. Significantly, PCN‐1004 functions as an outstanding catalyst in cross dehydrogenative coupling reactions for constructing C‐O/C‐S bonds, even in the absence of directing groups, achieving yields of up to ~99%, with long cycle lives and high substrate compatibility. PCN‐1004 outperforms all previously reported porphyrin‐based homogeneous and heterogeneous catalysts. Control experiments and computations elucidate the pivotal catalytic role of the copper‐Pz chains and reveal a free radical pathway for the reaction. This work not only demonstrates the successful implementation of a metal‐node‐based catalytic site anchoring strategy for the efficient catalysis of challenging organic transformations but also highlights the synergistic effect of a robust framework, 1D open channels, and active sites in enhancing catalytic efficiency within MOFs.

Simultaneous detection of CaMV35S and NOS using fluorescence sensors with dual-emission silver nanoclusters and catalytic hairpin amplification strategy.

Adual-emission fluorescent biosensing method was developed for simultaneous determinationof CaMV35S and NOS in genetically modified(GM) plants. Two designed hairpin DNA (H1, H2) sequences were used as templates to synthesize H1-AgNCs (λex = 570nm, λem = 625nm) and H2-AgNCs (λex = 470nm, λem = 555nm). By using H1-AgNCs and H2-AgNCs as dual-signal tags, combined with signal amplification strategy of magnetic separation to reduce background signal and an enzyme-free catalytic hairpin assembly (CHA) signal amplification strategy, a novel multi-target fluorescent biosensor was fabricated to detect multiple targets based on FRET between signal tags (donors) and magnetic Fe3O4 modified graphene oxide (Fe3O4@GO, acceptors). In the presence of the target NOS and CaMV35S, the hairpin structures of H1 and H2 can be opened respectively, and the exposed sequences will hybridize with the G-rich hairpin sequences HP1 and HP2 respectively, displacing the target sequences to participate in the next round of CHA cycle. Meanwhile, H1-HP1 and H2-HP2 double-stranded DNA sequences (dsDNA) were formed, resulting in the desorption of dsDNA from the surface of Fe3O4@GO due to weak π-π interaction between dsDNA and Fe3O4@GO and leading to the fluorescence recovery of AgNCs. Under optimal conditions, the linear ranges of this fluorescence sensor were 5 ~ 300nmol L-1 for NOS and 5 ~ 200nmol L-1 CaMV35S, and the LODs were 0.14nmol L-1 and 0.18nmol L-1, respectively. In addition, the fluorescence sensor has good selectivity for the detection of NOS and CaMV35S in GM soybean samples, showing the potential applications in GM screening.

Cobalt-Catalyzed Asymmetric Migratory Nozaki-Hiyama-Kishi Coupling.

Selective functionalization of ubiquitous C-H bonds based on 1,n-metal migration provides an attractive and sustainable route to access complex molecules from readily available precursors. Herein, we report a Co-catalyzed asymmetric reductive migratory Nozaki-Hiyama-Kishi (NHK) coupling between two readily available electrophiles, aryl (pseudo)halides and aldehydes, via an unprecedented through-space aryl-to-alkenyl 1,4-cobalt/hydride shift. The judicious choice of ligands is crucial for selectivity, leading to either ipso- or migratory NHK products with exquisite control of regio-, E/Z-, and enantioselectivity. Enabled by a ligand relay catalytic strategy, this platform has been further extended to aryl-to-aryl asymmetric migratory NHK coupling. These high-value NHK adducts, including α-chiral allylic alcohols and benzyl alcohols, are readily convertible to a variety of useful synthons.

Persistent ultraviolet luminescence and photocatalytic properties of SiO2-Zn2SiO4:Ga,Pb nanoparticles

Persistent phosphors possess unique afterglow optical properties. In this paper, a class of ultra-violet (UV) persistent luminescence nanoparticles were developed for catalytic photodegradation applications. UV persistent luminescence nanoparticles of SiO2-Zn2SiO4:Ga and SiO2-Zn2SiO4:Ga,Pb were successfully synthesized by using a mesoporous template method. The UV persistent luminescence intensity of SiO2-Zn2SiO4:Ga at 405 nm was enhanced up to ca. 3.5 times by co-doping with Pb2+ (396 nm), along with longer persistent luminescence duration. The photodegradation results indicate that it is useful to introduce UV persistent luminescence property into SiO2-Zn2SiO4:Ga,Pb to obtain enhanced catalytic activity of SiO2-Zn2SiO4 with a bigger catalytic oxidation reaction kinetic constant (up to ∼4 times). This kind of UV persistent catalysis strategy may become a potential feasible method for better catalytic photodegradation activity. The UV persistent photocatalyst has potential applications in the photooxidation of organic molecules in high chroma and/or turbidity aqueous systems.

Novel BDD-loaded bimetallic phosphide electrodes enable interesting bifunctional seawater electrolysis

The direct electrolysis of seawater for the production of green hydrogen energy is an economically attractive approach. However, this technique confronts technical problems because to the oxygen evolution reaction (OER) weak stability and inadequate selectivity due to competition with the chlorine evolution process. This work focuses on improving the stability of the electrode and electrolysis efficiency. The phosphating NiCoP active layer with 3D porous morphology was created by electrodeposition on the B-doped diamond (BDD) as an electrode inspired by the bifunctional catalysis strategy. The successfully constructed unique cube-on-nanosheets structure in the NiCoP active layer enables the electrode to exhibit excellent electrocatalytic performance. The porous NiCoP/BDD (Por-NiCoP/BDD) electrodes showed good catalytic activity in alkaline-simulated seawater with the OER and hydrogen evolution reaction (HER) overpotentials of 400 and 261 mV, respectively, at a current density of 100 mA cm−2. More importantly, the electrode exhibits interesting stability of the catalytic performance and structural in alkaline-simulated seawater electrolysis, with the current density decaying by only 1.52 % and 4.06 % after OER and HER processes for 50 h, respectively. This work expands the valuable application scenarios of BDD electrode and provides novel ideas for the development of seawater electrolysis.

Atroposelective Arene-Forming Wittig Reaction by Phosphorus PIII/PV=O Redox Catalysis.

The Wittig reaction is renowned as exceptionally versatile method for converting a diversity of aldehydes and ketones into alkenes. Recently, strategies for chiral phosphine catalysis under PIII/PV=O redox cycling emerged to render this venerable transformation stereoselective. Herein, we describe that phosphine redox catalysis enables the enantioselective synthesis of pertinent biaryl atropisomers by means of a stereocontrolled arene-forming Wittig reaction. Key to the process is the release of an endogenous base from readily accessible tert-butyloxycarbonylated Morita-Baylis-Hillman adducts triggered by catalyst intramolecularization, permitting mild phosphine redox catalysis for atroposelective Wittig reactions. By this strategy, a broad diversity of biaryl atropisomers is obtained with up to 94 : 6 enantioselectivity.

Halogen and Chalcogen Activation by Nucleophilic Catalysis.

The high utility of halogenated organic compounds has prompted the development of numerous transformations that install the carbon-halogen motif. Halogen functionalities, deemed as "functional and functionalizable" molecules due to their capacity to modulate diverse internal properties, constitute a pivotal strategy in drug discovery and development. Traditional routes to these building blocks have commonly involved multiple steps, harsh reaction conditions, and the use of stoichiometric and/or toxic reagents. With the emergence of solid halogen carriers such as N-halosuccinimides, and halohydantoins as popular sources of halonium ions, the past decade has witnessed enormous growth in the development of new catalytic strategies for halofunctionalization. This review aims to provide a nuanced perspective on nucleophilic activators and their roles in halogen activation. It will highlight critical discoveries in effecting racemic and asymmetric variants of these reactions, driven by the development of new catalysts, activation modes, and improved understanding of chemical reactivity and reaction kinetics.

Emerging Catalytic Strategies Driven by External Field for Heavy Metal Remediation

Heavy metal pollution presents significant environmental and public health risks due to its widespread occurrence and resistance to degradation. There is a pressing need for innovative solutions to address the challenge of heavy metal ion removal from water resources. In this review, we highlight recent advancements in emerging catalytic strategies for efficient heavy metal remediation, leveraging various external fields such as electric, mechanical, magnetic, and thermoelectric fields, as well as their synergetic coupling with photocatalysis technology. These novel approaches offer promising avenues for enhancing heavy metal removal efficacy and environmental sustainability. In particular, this review focuses on recent breakthroughs in new materials systems capable of functioning under diverse external fields, heralding future advancements in heavy metal remediation. Finally, we discuss the current challenges and future perspectives in this emerging research area.

Palladium‐Catalyzed Denitrogenative Coupling of Aryldiazonium Salts with Terminal Alkynes for the Assembly of Internal Alkynes

AbstractAn N‐heterocyclic carbene palladium (NHC‐palladium)‐catalyzed denitrogenative coupling of aryldiazonium salts with terminal alkynes in ionic liquids has been accomplished. This catalytic strategy provides an effective and green synthetic protocol for the assembly of structurally diverse internal alkynes with excellent functional group compatibility and mild conditions. In the presence of 1 mol % of IMes‐Pd‐Im‐Cl2 as the catalyst, a wide range of terminal alkynes and aryldiazonium salts could be excellently tolerated. Basic ionic liquid plays a crucial role in this catalytic system, which not only acts as the green solvent, but also provides basic environment for the carbon‐carbon bond formation process. Notably, this catalytic system could be recycled up to six times and reused without significant loss of catalytic activity.

Enzyme Cascade with Four Enzymes in One Pot for the Synthesis of L‐Phosphinothricin

AbstractThe biocatalytic oxidative deamination‐ reductive amination process for the production of L‐phosphinothricin (L‐PPT) from D,L‐phosphinothricin (D,L‐PPT) is a green and environmentally friendly approach with significant development potential. In this study, the adopted technological route involves the oxidative deamination of the D‐PPT component in D,L‐PPT to 2‐oxo‐4‐(hydroxymethylphosphinyl)butanoic acid (PPO) by utilizing D‐amino acid oxidase (DAAO), followed by the catalytic reductive amination of PPO to L‐PPT using phosphinothricin dehydrogenase (PpDH). In order to enhance the catalytic rate and reduce the inhibitory effect of the intermediate product PPO on the catalytic process, optimization of both oxidative deamination and reductive amination phases was conducted through separate strategies of constant‐pressure oxygen supply and substrate feeding, respectively. A “two‐step one‐pot” method was employed to link the optimized reactions, significantly shortening the production time. Furthermore, the “two‐step one‐pot” catalytic strategy was optimized, ultimately achieving a high 97.7% yield of L‐PPT with ee of L‐PPT>99.9% after 5.5 h of reaction under 800 mM D,L‐PPT catalytic conditions, D‐PPT and PPO could not bedetected in the reaction system, further enchanced the catalytic efficiency, production efficiency and product quality. The aforementioned results demonstrate that this proposed approach has great potential for industrial‐scale production of L‐PPT as well as significant competitive advantages in terms of economic feasibility.

Ammonium-Binding Bifunctional Aza-Crown Ether Catalysts for Substrate-Selective Hydroxyl Functionalization.

Herein, we describe a new bifunctional macrocyclic catalyst that employs multiple weak noncovalent interactions to enable substrate-selective O-silylation of ammonium alcohols over more reactive aliphatic alcohols with up to >20:1 substrate selectivity. Our catalytic strategy merges (i) the use of crown ethers as ammonium-binding receptors and (ii) the exploitation of N-methyl imidazole as a catalytic motif. Our collective mechanistic studies reveal the importance of receptor size, conformational preorganization, and the number of hydrogen-bonding acceptor units needed to achieve high selectivity within the macrocyclic binding pocket.

Tetra-Amido Macrocyclic Ligand (TAML) at Silicon(IV): A Structurally Constrained, Water-Soluble Silicon Lewis Superacid.

Tetracoordinate silicon species are typically tetrahedral, weak Lewis acids, and often sensitive to moisture. In this study, we present a tetra-amido macrocyclic ligand (TAML)-substituted Si(IV), isolated as its bis(pyridine) adduct. Due to structural constraint toward anti van't-Hof/Le Bel geometry, this compound exhibits Lewis superacidity and effectively catalyzes the hydroboration of pyridine. Kinetic and computational analyses of the catalytic cycle reveal that TAML-Si(IV) acts as a hydride transfer agent, and the hydrido silicate key intermediate is isolated. Notably, the Lewis acid is highly soluble (5 g/L) and long-term stable in water. Unlike previously described silicon-H2O adducts, the bound water becomes substantially acidified, reaching the Bro̷nsted superacidity range. A comparison of water affinity versus pKa lowering confirms our previous theory of the strength and the effect of Lewis acids. Overall, the compound's unlimited water compatibility and its mechanistically understood catalytic efficiency mark significant progress in applying structural constraint strategies for p-block element-based catalysis, while the acidification touches critical aspects of zeolite and silica surface chemistry.

Chiral-induced covalent organic framework as novel chiral stationary phase for chiral separation using open-tubular capillary electrochromatography

As a novel class of chiral stationary phase (CPS) material, chiral covalent organic frameworks (CCOFs) have already shown great promise in open-tubular capillary electrochromatography (OT-CEC) for chiral separation. The synthesis methods of CCOFs used in OT-CEC mainly include bottom-up, post modification and chiral induction. The CCOFs synthesized by bottom-up and post modification strategies already have lots of applications in capillary electrochromatography, however, the chiral-induced synthesized via an asymmetric catalytic strategy has not yet been reported for using as the chiral stationary phase (CPS) in OT-CEC or even in chromatographic separation. Herein, the chiral-induced COF (Λ)-TpPa-1 was synthesized by asymmetric catalytic synthesis and coated on the inner surface of a capillary by an in-situ growth strategy as the CPS for chiral drug separation. The baseline separation of six enantiomers was achieved within 14 min, with a high-resolution (Rs) range from 1.85 to 6.75. Moreover, the resolution and migration time of the capillary keep stable within 160 runs, showing its superior stability and repeatability. This research provides a new idea for the development and application of novel CPS materials in the field of capillary electrochromatography separation, also shows the new application of chiral induced COFs. Furthermore, the chiral-induced CCOFs can be easily applied to other chromatographic separation fields, exhibiting its extensive application value in chiral analysis separation.

Au@Pd nanozyme-mediated catalytic therapy: a novel strategy for targeting tumor microenvironment in cancer treatment

BackgroundBreast cancer, with its high morbidity and mortality rates, is a significant global health burden. Traditional treatments—surgery, chemotherapy, and radiotherapy—are widely used but come with drawbacks such as recurrence, metastasis, and significant side effects, including damage to healthy tissues. To address these limitations, new therapeutic strategies are being developed. Peroxidases (POD) can catalyze excess H2O2 in the tumor microenvironment to generate reactive oxygen species (ROS), which induce cancer cell apoptosis by disrupting redox homeostasis and modulating apoptosis-related proteins. However, natural enzymes face challenges like poor stability, high cost, and sensitivity to environmental conditions, limiting their application in breast cancer treatment. Nanozymes, nanomaterials with enzyme-like activity, offer a promising alternative by overcoming these limitations.MethodsIn this study, we successfully prepared Au@Pd nanozymes with peroxidase activity by depositing metallic Pd on Au nanoparticles (Au NPs) synthesized using a trisodium citrate reduction method and ascorbic acid reduction. The in vitro validation was conducted through a series of experiments, including ROS detection, flow cytometry, CCK-8 assay, DNA damage assessment, live/dead cell staining, Western blot (WB), and qPCR. Tumor treatment was performed via tail vein injection of the drug, followed by HE staining of the treated tissues and biochemical analysis of the blood.ResultsAu@Pd nanozymes can effectively accumulate at the tumor site through the EPR effect and exert peroxidase-like activity, catalyzing the excess H2O2 in the tumor microenvironment to produce ROS. This triggers apoptosis pathways and DNA damage, leading to the downregulation of the anti-apoptotic protein Bcl-2, upregulation of the pro-apoptotic protein Bax, and induction of apoptosis-related genes, demonstrating strong anti-tumor effects.ConclusionsThis study developed an efficient nanozyme-mediated catalytic therapy strategy targeting the tumor microenvironment for the treatment of breast cancer cells.

Regio-, stereo-, and enantioselective ipso- and migratory defluorinative olefin cross-coupling to access highly functionalized monofluoroalkenes

Monofluoroalkenes serve as nonhydrolyzable mimetics of amides and are frequently encountered in drug candidates. Herein we report a regio-, enantio-, and stereoselective NiH-catalyzed ipso- and migratory defluorinative olefin cross-coupling employing readily available olefins and gem-difluoroalkenes under mild conditions. This approach enables the efficient synthesis of a broad array of structurally diverse monofluoroalkenes bearing a tertiary allylic stereogenic center. Mechanistically, the challenging migratory defluorinative olefin cross-coupling process is successfully realized through a ligand relay catalytic strategy, enabling the formal C(sp3)–H/C(sp2)–F activation with high levels of regio-, stereo-, and enantiocontrol.

Recent advances in the bioproduction of mannitol

D-mannitol is a six-carbon sugar alcohol and one of the most abundant polyols in the nature. With antioxidant and osmotic pressure-regulating effects and non-metabolism by the human body, D-mannitol has been widely used in functional food and pharmaceutical industries. At present, a major way for industrial production of D-mannitol is chemical hydrogenation. In addition, D-Mannitol can be produced by microbial metabolism or catalysis. Compared with the chemical hydrogenation, the microbial methods for synthesizing mannitol do not produce sorbitol as a by-product and have the advantages of mild reaction conditions, strong specificity, and high conversion rate. Microbial fermentation is praised for easy access of strains and raw materials and simple separation of the product. Microbial catalysis usually adopts a multi-enzyme coupling strategy, which uses enzymes produced by engineered bacteria for whole-cell catalysis, and the cofactor recycling pathway is introduced to replenish expensive cofactor. This method can achieve high yields with cheap substrates under mild conditions without the formation of by-products. However, the application of microbial methods in the industrial production of D-mannitol is limited by the high costs of fermentation media and substrates and the long reaction time. This article reviews the reported microbial methods for producing D-mannitol, including the use of high-yielding strains and their fermentation processes, the utilization of low-cost substrates, whole-cell catalytic strategies, and the process control for high productivity. The biosynthesis of mannitol is not only of great significance for promoting industrial upgrading and realizing green manufacturing, but also provides strong support for the development of new bio-based products to meet the growing market demand. With the continuous improvement of technological innovation and industrial chain, it is expected to become one of the main ways of mannitol production in the future.