Formaldehyde Ambient-Temperature Decomposition over Pd/Mn3O4-MnO Driven by Active Sites' Self-Tandem Catalysis.

The widespread presence of formaldehyde (HCHO) pollutant has aroused significant environmental and health concerns. The catalytic oxidation of HCHO into CO2 and H2O at ambient temperature is regarded as one of the most efficacious and environmentally friendly approaches; to achieve this, however, accelerating the intermediate formate species formation and decomposition remains an ongoing obstacle. Herein, a unique tandem catalytic system with outstanding performance in low-temperature HCHO oxidation is proposed on well-structured Pd/Mn3O4-MnO catalysts possessing bifunctional catalytic centers. Notably, the optimized tandem catalyst achieves complete oxidation of 100 ppm of HCHO at just 18 °C, much better than the Pd/Mn3O4 (30%) and Pd/MnO (27%) counterparts as well as other physical tandem catalysts. The operando analyses and physical tandem investigations reveal that HCHO is primarily activated to gaseous HCOOH on the surface of Pd/Mn3O4 and subsequently converted to H2CO3 on the Pd/MnO component for deep decomposition. Theoretical studies disclose that Pd/Mn3O4 exhibits a favorable reaction energy barrier for the HCHO → HCOOH step compared to Pd/MnO; while conversely, the HCOOH → H2CO3 step is more facilely accomplished over Pd/MnO. Furthermore, the nanoscale intimacy between two components enhances the mobility of lattice oxygen, thereby facilitating interfacial reconstruction and promoting interaction between active sites of Pd/Mn3O4 and Pd/MnO in local vicinity, which further benefits sustained HCHO tandem catalytic oxidation. The tandem catalysis demonstrated in this work provides a generalizable platform for the future design of well-defined functional catalysts for oxidation reactions.

Boosted Light Alkane Deep Oxidation via Metal Bond Length Modulation-Induced C-C Bond Preferential Activation.

Light alkanes (LAs), typical VOCs existing in both stationary and mobile sources, pose significant environmental concerns. Although noble metal catalysts demonstrate strong C-H bond activation, their effectiveness in degrading LAs is hindered by inherent challenges, including poor chemical stability and water resistance. Here, from a new perspective, we propose a feasible strategy that adjusting the metal bond lengths within Pd clusters through partial substitution of smaller radius 3d transition metals (3dTMs) to prioritize the activation of low-energy C-C bonds within LAs. Benefiting from this, PdCo/CeO2 exhibits exceptional catalytic performance in propane degradation due to their high capacity for C-C cleavage stemming from the shorter Pd-Co length (2.51 Å) and lower coordination number (1.73), boosting the activation of α-H and ß-H of propane simultaneously and accelerating the mobility of postactivated oxygen species to prevent Pd center deep oxidation. The presence of 3dTMs on Pd clusters improves the redox and charge transfer ability of catalysts, resulting in an amplified generation of oxygen vacancies and facilitating the adsorption and activation of reactants. Mechanistic studies and DFT calculations suggest that the substitution of 3dTMs significantly accelerate C-C bond cleavage within C3 intermediates to generate the subsequent C2 and C1 intermediates, suppressing the generation of harmful byproducts.

Constructing Pd@Layered-CoOx/MFI Bifunctional Catalyst for Efficient Ethyl Acetate Oxidation: Boosted C═O Activation and *O Species Transformation.

Oxygenated volatile organic compounds (OVOCs), emitted in large quantities by the chemical industry, are a major contributor to the formation of ozone and subsequent particulate matter. For the efficient catalytic oxidation of OVOCs, the challenges of molecular activation and intermediate inhibition remain. The construction of bifunctional active sites with specific structures offers a promising way to overcome these problems. Here, the Pd@Layered-CoOx/MFI bifunctional catalyst with core-shell active sites was rationally fabricated though a two-step ligand pyrolysis method, which exhibits a superb oxidation efficiency toward ethyl acetate (EA). Over this, 13.4% of EA (1000 ppm) can be oxidized at just 140 °C with a reaction rate of 13.85 mmol·gPd-1·s-1, around 176.7 times higher than that of the conventional Pd-CoOx/MFI catalyst. The electronic coupling of the Pd-Co pair promotes the electron back-donation from Pd nanoparticles to the layered CoOx shell and facilitates the formation of Pd2+ species, which greatly enhances the adsorption and activation of the electron-rich C═O bond of the EA molecules. In addition, the synergy of these core-shell Pd@Layered-CoOx sites accelerates the activation and transformation of *O species, which inhibit the formation of acetaldehyde and ethanol byproducts, ensuring the rapid total oxidation of EA molecules via the Mars-van Krevelen mechanism. This work established a solid foundation for exploring robust bifunctional catalysts for deep OVOC purification.

1,2-Difunctionalized bicyclo[1.1.1]pentanes: Long-sought-after mimetics for ortho/meta-substituted arenes.

The development of a versatile platform for the synthesis of 1,2-difunctionalized bicyclo[1.1.1]pentanes to potentially mimic ortho/meta-substituted arenes is described. The syntheses of useful building blocks bearing alcohol, amine, and carboxylic acid functional handles have been achieved from a simple common intermediate. Several ortho- and meta-substituted benzene analogs, as well as simple molecular matched pairs, have also been prepared using this platform. The results of in-depth ADME (absorption, distribution, metabolism, and excretion) investigations of these systems are presented, as well as computational studies which validate the ortho- or meta-character of these bioisosteres.

Simplifying Access to Targeted Protein Degraders via Nickel Electrocatalytic Cross-Coupling.

C-C linked glutarimide-containing structures with direct utility in the preparation of cereblon-based degraders (PROTACs, CELMoDs) can be assessed in a single step from inexpensive, commercial α-bromoglutarimide through a unique Brønsted-acid assisted Ni-electrocatalytic approach. The reaction tolerates a broad array of functional groups that are historically problematic and can be applied to the simplified synthesis of dozens of known compounds that have only been procured through laborious, wasteful, multi-step sequences. The reaction is scalable in both batch and flow and features a trivial procedure wherein the most time-consuming aspect of reaction setup is weighing out the starting materials.

Enantioselective Total Synthesis of (+)-KB343.

A concise total synthesis of the complex guanidinium toxin KB343 is reported traversing through an unusual sequence of chemoselective transformations and strategic skeletal reorganization. The absolute configuration is confirmed through an enantioselective route, and the structures of all key intermediates and the natural product itself are unassailably confirmed through X-ray crystallographic analysis.

Divergent Synthetic Approach to Grayanane Diterpenoids.

The total syntheses of nine grayanane diterpenoids, namely, GTX-II (1), GTX-III (2), rhodojaponin III (3), GTX-XV (4), principinol D (5), iso-GTX-II (6), 1,5-seco-GTX-Δ1,10-ene (7), and leucothols B (8) and D (9), that belong to five distinct subtypes, were disclosed in a divergent manner. Among them, six members were accomplished for the first time. The concise synthetic approach features three key transformations: (1) an oxidative dearomatization-induced [5 + 2] cycloaddition/pinacol rearrangement cascade to assemble the bicyclo[3.2.1]octane carbon framework (CD rings); (2) a photosantonin rearrangement to build up the 5/7 bicycle (AB rings) of 1-epi-grayanoids; and (3) a Grob fragmentation/carbonyl-ene process to access four additional subtypes of grayanane skeletons. Density functional theory calculations were performed to elucidate the mechanistic origins of the crucial divergent transformation, which combined with late-stage synthetic findings provided insights into the biosynthetic relationships between these diverse skeletons.

Physicochemical Effects of Sulfur Precursors on Sulfidated Amorphous Zero-Valent Iron and Its Enhanced Mechanisms for Cr(VI) Removal.

Amorphous zerovalent iron (AZVI) has gained considerable attention due to its remarkable reactivity, but there is limited research on sulfidated amorphous zerovalent iron (SAZVI) and the influence of different sulfur precursors on its reactivity remains unclear. In this study, SAZVI materials with an amorphous structure were synthesized using various sulfur precursors, resulting in significantly increased specific surface area and hydrophobicity compared to AZVI. The Cr(VI) removal efficiency of SAZVI-Na2S, which exhibited the most negative free corrosion potential (-0.82 V) and strongest electron transfer ability, was up to 8.5 times higher than that of AZVI. Correlation analysis revealed that the water contact angle (r = 0.87), free corrosion potential (r = -0.92), and surface Fe(II) proportion (r = 0.98) of the SAZVI samples played crucial roles in Cr(VI) removal. Furthermore, the enhanced elimination ability of SAZVI-Na2S was analyzed, primarily attributed to the adsorption of Cr(VI) by the FeSx shell, followed by the rapid release of internal electrons to reduce Cr(VI) to Cr(III). This process ultimately led to the precipitation of FeCr2O4 and Cr2S3 on the surface of SAZVI-Na2S, resulting in their removal from the water. This study provides insights into the influence of sulfur precursors on the reactivity of SAZVI and offers a new strategy for designing highly active AZVI for efficient Cr(VI) removal.

Fabricating Amorphous Zero-Valent Iron for Cr(VI) Efficient Reduction: Unveiling the Effect of Ethylenediamine on Physicochemical Properties.

Amorphous zero-valent iron (AZVI) has attracted wide attention due to its high-efficiency reduction ability. However, the effect of different EDA/Fe(II) molar ratios on the physicochemical properties of the synthesized AZVI requires further investigation. Herein, series of AZVI samples were prepared by changing the molar ratio of EDA/Fe(II) to 1/1 (AZVI@1), 2/1 (AZVI@2), 3/1 (AZVI@3), and 4/1 (AZVI@4). When the EDA/Fe(II) ratio increased from 0/1 to 3/1, the Fe0 proportion on the AZVI surface increased from 26.0 to 35.2% and the reducing ability was enhanced. As for AZVI@4, the surface was severely oxidized to form a large amount of Fe3O4, and the Fe0 content was only 74.0%. Moreover, the removal ability of Cr(VI) was in the order AZVI@3 > AZVI@2 > AZVI@1 > AZVI@4. The isothermal titration calorimetry results revealed that the increase of the molar ratio of EDA/Fe(II) would lead to the stronger complexation of EDA with Fe(II), which resulted in the gradual decrease of the yield of AZVI@1 to AZVI@4 and the gradual deterioration of water pollution after the synthesis. Therefore, based on the evaluation of all indicators, AZVI@2 was the optimal material, not only because its yield was as high as 88.7% and the secondary water pollution level was low, but most importantly, the removal efficiency of Cr(VI) by AZVI@2 was excellent. Furthermore, the actual Cr(VI) wastewater with the concentration of 14.80 mg/L was treated with AZVI@2, and the removal rate of 97.0% was achieved after only a 30 min reaction. This work clarified the effect of different ratios of EDA/Fe(II) on the physicochemical properties of AZVI, which provided insights for guiding the reasonable synthesis of AZVI and is also conducive to investigating the reaction mechanism of AZVI in Cr(VI) remediation.

Acetone Efficient Degradation under Simulated Humid Conditions by Mn-O-Pt Interaction Taming-Triggered Water Dissociation Intensification.

As a generally existing component in industrial streams, H2O usually inhibits the catalytic degradation efficiency of volatile organic compounds (VOCs) greatly. Here, we propose a novel strategy that accelerates the H2O dissociation and facilitates positive feedbacks during VOC oxidation by fabricating citric acid (CA)-assisted Pt(K)-Mn2O3/SiO2 (Pt-Mn/KS-xCA). Results reveal that the complexation of carboxyl groups of citric acid with Mn cations leads to the formation of small Mn2O3 (4.1 ± 0.2 nm) and further enhances the Mn-O-Pt interaction (strengthened by the Si-O-Mn interaction), which can transfer more electrons from Pt-Mn/KS-6CA to H2O, thus facilitating its breaking of covalent bonds. It subsequently produces abundant surface hydroxyl groups, improving the adsorption and activation abilities of acetone reactant and ethanol intermediate. Attributing to these, the acetone turnover frequency value of Pt-Mn/KS-6CA is 1.8 times higher than that of Pt-Mn/KS at 160 °C, and this multiple changes to 6.3 times in the presence of H2O. Remarkably, acetone conversion over Pt-Mn/KS-6CA increases by up to 14% in the presence of H2O; but it decreases by up to 26% for Pt-Mn/KS due to its weak dissociation ability and high adsorption capacity toward H2O. This work sheds new insights into the design of highly efficient catalytic materials for VOC degradation under humid conditions.

Risk factors of recurrent choledocholithiasis following therapeutic endoscopic retrograde cholangiopancreatography.

BACKGROUND: The risk factors for the recurrent choledocholithiasis after endoscopic retrograde cholangiopancreatography (ERCP) have not been well studied. The aim of this study was to explore the risk factors of recurrent choledocholithiasis. METHODS: We carried out a retrospective analysis of data collected between January 1, 2010 and January 1, 2020. Univariate analysis and multivariate analysis were used to explore the independent risk factors of recurrent choledocholithiasis following therapeutic ERCP. RESULTS: In total, 598 patients were eventually selected for analysis, 299 patients in the recurrent choledocholithiasis group and 299 patients in the control group. The overall rate of recurrent choledocholithiasis was 6.91%. Multivariate analysis showed that diabetes [odds ratio (OR) = 3.677, 95% confidence interval (CI): 1.875-7.209; P < 0.001], fatty liver (OR = 4.741, 95% CI: 1.205-18.653; P = 0.026), liver cirrhosis (OR = 3.900, 95% CI: 1.358-11.201; P = 0.011), history of smoking (OR = 3.773, 95% CI: 2.060-6.908; P < 0.001), intrahepatic bile duct stone (OR = 4.208, 95% CI: 2.220-7.976; P < 0.001), biliary stent (OR = 2.996, 95% CI: 1.870-4.800; P < 0.001), and endoscopic papillary balloon dilation (EPBD) (OR = 3.009, 95% CI: 1.921-4.715; P < 0.001) were independent risk factors of recurrent choledocholithiasis. However, history of drinking (OR = 0.183, 95% CI: 0.099-0.337; P < 0.001), eating light food frequently (OR = 0.511, 95% CI: 0.343-0.760; P = 0.001), and antibiotic use before ERCP (OR = 0.315, 95% CI: 0.200-0.497; P < 0.001) were independent protective factors of recurrent choledocholithiasis. CONCLUSIONS: Patients with the abovementioned risk factors are more likely to have recurrent CBD stones. Patients who eat light food frequently and have a history of drinking are less likely to present with recurrent CBD calculi.

Ni-Catalyzed Enantioselective Dialkyl Carbinol Synthesis via Decarboxylative Cross-Coupling: Development, Scope, and Applications.

The first enantioselective decarboxylative Negishi-type alkylations of α-oxy carboxylic acids are reported via the intermediacy of redox-active esters (RAEs). This transformation enables a radical-based retrosynthesis of seemingly trivial enantiopure dialkyl carbinols. This article includes a discussion of the history of such couplings, the retrosynthetic ramifications of such a coupling, the development of general conditions, and an extensive series of applications that vividly demonstrate how it can simplify synthesis.

Biotemplate Fabrication of Hollow Tubular CexSr1-xTiO3 with Regulable Surface Acidity and Oxygen Mobility for Efficient Destruction of Chlorobenzene: Intrinsic Synergy Effect and Reaction Mechanism.

Developing economic and applicable catalysts with elegant chlorine resistance and organic byproduct inhibition capability is of great significance for chlorinated volatile organic compounds (Cl-VOCs) eco-friendly purification. Here, ternary CexSr1-xTiO3 catalysts with tunable surface acidity and oxygen species mobility were creatively fabricated using the hollow tubular-structured fruit hair of Platanus (FHP; a widespread greenery waste) as the scaffolding biotemplate. It is shown that the oxygen vacancy (Ov) triggered by the presence of Ce can optimize the synergy between the Lewis acid sites (LAS) and Brønsted acid sites (BAS). High concentration of Ov and BAS promotes the C-Cl cleavage of chlorobenzene (CB) and accelerates the desorption of Cl• radicals as inorganic chlorine. Simultaneously, the strong electron transfer within Ti-Ce-Sr linkage increases the acidity of LAS, resulting in the superior reducibility of Ce0.4Sr0.6TiO3 and facilitating the deep oxidation of dechlorination intermediates. Additionally, the spatial confinement of the tubular structure remarkably accelerates the CB flow rate and reduces the residence time of byproducts over the prepared catalysts. Owing to these, CB can be efficiently destructed over Ce0.4Sr0.6TiO3 with selectivity of CO2 and inorganic chlorine dramatically enhanced, respectively, approximately 16 and 21 times at 275 °C compared to those of pure SrTiO3. The present work provides a feasible and promising strategy for engineering efficient catalysts for heterogeneous thermocatalytic reactions for industrial-scale Cl-CVOC destruction.

Evaluation of the Flexibility for Catalytic Ozonation of Dichloromethane over Urchin-Like CuMnOx in Flue Gas with Complicated Components.

The evaluation of the poisoning effect of complex components in practical gas on DCM (dichloromethane) catalytic ozonation is of great significance for enhancing the technique's environmental flexibility. Herein, Ca, Pb, As, and NO/SO2 were selected as a typical alkaline-earth metal, heavy metal, metalloid, and acid gas, respectively, to evaluate their interferences on catalytic behaviors and surface properties of an optimized urchin-like CuMn catalyst. Ca/Pb loading weakens the formation of oxygen vacancies, oxygen mobility, and acidity due to the fusion of Mn-Ca/Pb-O, leading to their inferior catalytic performance with poor CO2 selectivity and mineralization rate. Noticeably, the presence of As induces excessively strong acidity, facilitating the inevitable formation of byproducts. Catalytic co-ozonation of NO/DCM is achieved with stoichiometric ozone addition. Unfortunately, SO2 introduction brings irreversible deactivation due to strong competition adsorption and the loss of active sites. Unexpectedly, Ca loading protects active sites from an attack by SO2. The formation of unstable sulfites and the released Mn-O structure offset the negative effect from SO2. Overall, the catalytic ozonation of DCM exhibits a distinctive priority in the antipoisoning of metals with the maintenance of DCM conversion. The construction of more stable acid sites should be the future direction of catalyst design; otherwise, catalytic ozonation should be arranged together with post heavy metal capture and a deacidification system.

Rationally Engineering a CuO/Pd@SiO2 Core-Shell Catalyst with Isolated Bifunctional Pd and Cu Active Sites for n-Butylamine Controllable Decomposition.

Volatile organic amines are a category of typical volatile organic compounds (VOCs) extensively presented in industrial exhausts causing serious harm to the atmospheric environment and human health. Monometallic Pd and Cu-based catalysts are commonly adopted for catalytic destruction of hazardous organic amines, but their applications are greatly limited by the inevitable production of toxic amide and NOx byproducts and inferior low-temperature activity. Here, a CuO/Pd@SiO2 core-shell-structured catalyst with diverse functionalized active sites was creatively developed, which realized the total decomposition of n-butylamine at 260 °C with a CO2 yield and N2 selectivity reaching up to 100% and 98.3%, respectively (obviously better than those of Pd@SiO2 and CuO/SiO2), owing to the synergy of isolated Pd and Cu sites in independent mineralization of n-butylamine and generation of N2, respectively. The formation of amide and short-chain aliphatic hydrocarbon intermediates via C-C bond cleavage tended to occur over Pd sites, while the C-N bond was prone to breakage over Cu sites, generating NH2· species and long free-N chain intermediates at low temperatures, avoiding the production of hazardous amide and NOx. The SiO2 channel collapse and H+ site production resulted in the formation of N2O via suppressing NH2· diffusion. This work provides critical guidance for a rational fabrication of catalysts with high activity and N2 selectivity for environmentally friendly destruction of nitrogen-containing VOCs.

CircRNF121 knockdown suppresses the progression of cervical cancer by regulating miR-153-3p/ATF2 axis and wnt/ß-catenin pathway.

Cervical cancer (CC) is a common malignancy in gynecology. Emerging evidence has demonstrated that circular RNAs (circRNAs) act as vital mediators in CC. However, the roles of circRNA ring finger protein 121 (circRNF121) in CC are largely unknown. Herein, we focused on the exact function and underlying mechanism of circRNF121 in CC development. Our results showed that circRNF121 was highly expressed in CC tissues and cells. Knockdown of circRNF121 suppressed cell growth, metastasis, epithelial-mesenchymal transition (EMT), autophagy, and wnt/ß-catenin pathway in CC cells in vitro and blocked tumor formation in vivo. For mechanism investigation, circRNF121 could affect activating transcription factor 2 (ATF2) expression by decoying miR-153-3p, thereby accelerating CC cell development. In conclusion, circRNF121 exerted the tumor-suppressive role in CC progression by altering miR-153-3p/ATF2 axis. These results suggested that circRNF121 might be a possible circ-targeted therapy for patients with CC.

Total Synthesis of Kibdelomycin.

A modular total synthesis of kibdelomycin is disclosed that should enable structure-activity relationship (SAR) studies of this interesting class of antibiotics. The route uses simple building blocks and addresses lingering questions about its structural assignment and relationship to amycolamicin, a recently described natural product reported to have a similar structure. Initial antibacterial assays reveal that both C-22 epimers (the N-glycosidic linkage) of the natural product have similar activity while structurally truncated analogs lose activity.

Modulating the Electronic Metal-Support Interactions in Single-Atom Pt1 -CuO Catalyst for Boosting Acetone Oxidation.

The development of highly active single-atom catalysts (SACs) and identifying their intrinsic active sites in oxidizing industrial hazardous hydrocarbons are challenging prospects. Tuning the electronic metal-support interactions (EMSIs) is valid for modulating the catalytic performance of SACs. We propose that the modulation of the EMSIs in a Pt1 -CuO SAC significantly promotes the activity of the catalyst in acetone oxidation. The EMSIs promote charge redistribution through the unified Pt-O-Cu moieties, which modulates the d-band structure of atomic Pt sites, and strengthens the adsorption and activation of reactants. The positively charged Pt atoms are superior for activating acetone at low temperatures, and the stretched Cu-O bonds facilitate the activation of lattice oxygen atoms to participate in subsequent oxidation. We believe that this work will guide researchers to engineer efficient SACs for application in hydrocarbon oxidation reactions.

N-Ammonium Ylide Mediators for Electrochemical C-H Oxidation.

The site-specific oxidation of strong C(sp3)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds to truncating retrosynthetic plans, there is a growing need for new reagents and methods for achieving such a transformation in both academic and industrial circles. One main drawback of current chemical reagents is the lack of diversity with regard to structure and reactivity that prevents a combinatorial approach for rapid screening to be employed. In that regard, directed evolution still holds the greatest promise for achieving complex C-H oxidations in a variety of complex settings. Herein we present a rationally designed platform that provides a step toward this challenge using N-ammonium ylides as electrochemically driven oxidants for site-specific, chemoselective C(sp3)-H oxidation. By taking a first-principles approach guided by computation, these new mediators were identified and rapidly expanded into a library using ubiquitous building blocks and trivial synthesis techniques. The ylide-based approach to C-H oxidation exhibits tunable selectivity that is often exclusive to this class of oxidants and can be applied to real-world problems in the agricultural and pharmaceutical sectors.

Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.