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Electrophilic halogenation reactions have been a reliable approach to accessing organohalides. During the past decades, various catalytic systems have been developed for the activation of haleniums. However, there is still a short of effective catalysts, which could cover various halogenation reactions and broad scope of unsaturated compounds. Herein, TEMPO (2,2,6,6-tetramethylpiperidine nitroxide) and its derivatives are disclosed as active catalysts for electrophilic halogenation of olefins, alkynes, and aromatics. These catalysts are stable, readily available, and reactive enough to activate haleniums including Br + , I + and even Cl + reagents. This catalytic system is applicable to various halogenations including haloarylation of olefins or dibromination of alkynes, which were rarely realized in previous Lewis base catalysis or Lewis acid catalysis. The high catalytic ability is attributed to a synergistic activation model of electrophilic halogenating reagents, where the carbonyl group and the halogen atom are both activated by present TEMPO catalysis. Organohalides are widely used as synthetic precursors and target products, but for various halogenation reactions there is a need for effective catalysts to activate commercially available haleniums. Here, the authors report that TEMPO and its derivatives are active catalysts for electrophilic halogenation of olefins, alkynes and aromatics, under mild reaction conditions and with good functional group tolerance.

The photochemical properties of Electron Donor-Acceptor (EDA) complexes present exciting opportunities for synthetic chemistry. However, these strategies often require an inert atmosphere to maintain high efficiency. Herein, we develop an EDA complex photocatalytic system through rational design, which overcomes the oxygen-sensitive limitation of traditional EDA photocatalytic systems and enables aerobic oxygenation reactions through dioxygen activation. The mild oxidation system transfers electrons from the donor to the effective catalytic acceptor upon visible light irradiation, which are subsequently captured by molecular oxygen to form the superoxide radical ion, as demonstrated by the specific fluorescent probe, dihydroethidine (DHE). Furthermore, this visible-light mediated oxidative EDA protocol is successfully applied in the aerobic oxygenation of boronic acids. We believe that this photochemical dioxygen activation strategy enabled by EDA complex not only provides a practical approach to aerobic oxygenation but also promotes the design and application of EDA photocatalysis under ambient conditions. The photochemical properties of Electron Donor-Acceptor (EDA) complexes present exciting opportunities, but often require an inert atmosphere to maintain high efficiency. Here, the authors develop a photocatalytic system through rational design, which overcomes the oxygen-sensitive limitation of traditional EDA photocatalytic systems.

Metal-organic frameworks (MOFs) are a novel class of crystalline materials which find widespread applications in the field of microporous conductors, catalysis, separation, biomedical engineering, and electrochemical sensing. With a specific emphasis on the MOF composites for electrochemical sensor applications, this review summarizes the recent construction strategies on the development of conductive MOF composites (post-synthetic modification of MOFs, in situ synthesis of functional materials@MOFs composites, and incorporating electroactive ligands). The developed composites are revealed to have excellent electrochemical sensing activity better than their pristine forms. Notably, the applicable functionalized MOFs to electrochemical sensing/biosensing of various target species are discussed. Finally, we highlight the perspectives and challenges in the field of electrochemical sensors and biosensors for potential directions of future development. Graphical Abstract

Molecular structure-editing through nitrogen insertion offers more efficient and ingenious pathways for the synthesis of nitrogen-containing compounds, which could benefit the development of synthetic chemistry, pharmaceutical research, and materials science. Substituted amines, especially nitrogen-containing alkyl heterocyclic compounds, are widely found in nature products and drugs. Generally, accessing these compounds requires multiple steps, which could result in low efficiency. In this work, a molecular editing strategy is used to realize the synthesis of nitrogen-containing compounds using aryl alkanes as starting materials. Using derivatives of O -tosylhydroxylamine as the nitrogen source, this method enables precise nitrogen insertion into the C sp 2 -C sp 3 bond of aryl alkanes. Notably, further synthetic applications demonstrate that this method could be used to prepare bioactive molecules with good efficiency and modify the molecular skeleton of drugs. Furthermore, a plausible reaction mechanism involving the transformation of carbocation and imine intermediates has been proposed based on the results of control experiments. Substituted amines, especially nitrogen containing alkyl heterocyclic compounds, are widely found in nature products and drugs, but generally accessing these compounds requires multiple steps. Herein, the authors report a molecular editing strategy for the synthesis of nitrogen-containing compounds using aryl alkanes as starting materials.

Organic azides are key motifs in compounds of relevance to chemical biology, medicinal chemistry and materials science. In addition, they also serve as useful building blocks due to their remarkable reactivity. Therefore, the development of efficient protocols to synthesize these compounds is of great significance. This paper reviews the major applications and development of azidation in difunctionalization of olefins using azide reagents.

The Schmidt reaction has been an efficient and widely used synthetic approach to amides and nitriles since its discovery in 1923. However, its application often entails the use of volatile, potentially explosive, and highly toxic azide reagents. Here, we report a sequence whereby triflic anhydride and formic and acetic acids activate the bulk chemical nitromethane to serve as a nitrogen donor in place of azides in Schmidt-like reactions. This protocol further expands the substrate scope to alkynes and simple alkyl benzenes for the preparation of amides and nitriles.

A valuable introduction to green oxidation for organic chemists interested in discovering new strategies and new reactions for oxidative synthesis Green Oxidation in Organic Synthesis provides a comprehensive introduction and overview of chemical preparation by green oxidative processes, an entry point to the growing journal literature on green.

Red mud (RM) and phosphogypsum (PG) are two typical industrial waste around the world, which are being generated and landfilled massively per year. This study investigates the collaborative effects of RM and PG on geotechnical properties of cement-stabilized dredged clay. Unconfined compressive strength (UCS) tests, isotropically consolidated undrained triaxial (ICUT) tests and one-dimensional consolidation tests were performed. The strength and deformation characteristics of stabilized clay were examined with 16% cement and different proportions of RM and PG (10%RM, 7.5%RM2.5%PG, 5%RM5%PG, 2.5%RM7.5%PG and 10%PG). The RM and PG are found complementary and effective in improving geotechnical properties of stabilized clay. The UCS of the cement-stabilized clay nearly triples at an optimal proportion of RM and PG at early curing period. The specimen with a high content of RM has stronger cementation bonds and exhibits a brittle behavior during undrained shearing process. A high content of PG, whereas, results in a lower peak strength but a larger failure strain of the specimen. The specimen with a high content of PG also exhibits a much smaller compression index at pre-yield stage. In addition, the evolution in microstructure of stabilized clay with different RM/PG proportions is explored using a series of microscopic tests. It is shown that the collaborative effects of RM and PG are dependent upon the cementation strengthening effects of alkaline RM and pore-filling effects of ettringite generated from PG. The role of ettringite significantly relies on the surrounding void space considering the pore-filling effects and the potential cementation damage.

Background Postoperative cognitive dysfunction (POCD) is a common complication after surgery, especially amongst elderly patients. Neuroinflammation and iron homeostasis are key hallmarks of several neurological disorders. In this study, we investigated the role of deferoxamine (DFO), a clinically used iron chelator, in a mouse model of surgery-induced cognitive dysfunction and assessed its neuroprotective effects on neuroinflammation, oxidative stress, and memory function. Methods A model of laparotomy under general anesthesia and analgesia was used to study POCD. Twelve to 14 months C57BL/6J male mice were treated with DFO, and changes in iron signaling, microglia activity, oxidative stress, inflammatory cytokines, and neurotrophic factors were assessed in the hippocampus on postoperative days 3, 7, and 14. Memory function was evaluated using fear conditioning and Morris water maze tests. BV2 microglia cells were used to test the anti-inflammatory and neuroprotective effects of DFO. Results Peripheral surgical trauma triggered changes in hippocampal iron homeostasis including ferric iron deposition, increase in hepcidin and divalent metal transporter-1, reduction in ferroportin and ferritin, and oxidative stress. Microglia activation, inflammatory cytokines, brain-derived neurotropic factor impairments, and cognitive dysfunction were found up to day 14 after surgery. Treatment with DFO significantly reduced neuroinflammation and improved cognitive decline by modulating p38 MAPK signaling, reactive oxygen species, and pro-inflammatory cytokines release. Conclusions Iron imbalance represents a novel mechanism underlying surgery-induced neuroinflammation and cognitive decline. DFO treatment regulates neuroinflammation and microglia activity after surgery.

To utilize discarded shield residue and alleviate the shortage of subgrade filling, industrial wastes such as calcium carbide slag (CCS) and fly ash (FA) were considered to enhance the mechanical properties of the shield residue. A series of laboratory tests, including California Bearing Ratio (CBR) tests, unconfined compressive strength (UCS) tests, moisture content tests, pH tests, water stability tests, and dry-wet cycles tests were performed on discarded shield residue with additive contents. The results show that the UCS and CBR values enhanced significantly with the increase in curing time. However, the moisture content and pH of the stabilized soil exhibited a decreasing trend. The early UCS of CCS-FA stabilized soil is slightly lower than that of QL-FA stabilized soil. After 60 curing days, all stabilized soil exhibited a UCS value exceeding 1.9 MPa. In addition, the CBR values of CCS-FA stabilized soil were more than 8 times higher than those of the original shield residue. Furthermore, the water stability of CCS-FA stabilized soil is slightly better than QL-FA stabilized soil, especially at 7 days and 14 days. As for dry-wet cycles test, after the fifth cycle, the CCS-FA stabilized soil maintained overall integrity. The CCS can effectively replace QL to enhance the mechanical properties of shield residue as subgrade filling.