This Review summarizes advances in fluorination by C(sp2)−H and C(sp3)−H activation. Transition‐metal‐catalyzed approaches championed by palladium have allowed the installation of a fluorine ...substituent at C(sp2) and C(sp3) sites, exploiting the reactivity of high‐oxidation‐state transition‐metal fluoride complexes combined with the use of directing groups (some transient) to control site and stereoselectivity. The large majority of known methods employ electrophilic fluorination reagents, but methods combining a nucleophilic fluoride source with an oxidant have appeared. External ligands have proven to be effective for C(sp3)−H fluorination directed by weakly coordinating auxiliaries, thereby enabling control over reactivity. Methods relying on the formation of radical intermediates are complementary to transition‐metal‐catalyzed processes as they allow for undirected C(sp3)−H fluorination. To date, radical C−H fluorinations mainly employ electrophilic N−F fluorination reagents but a unique MnIII‐catalyzed oxidative C−H fluorination using fluoride has been developed. Overall, the field of late‐stage nucleophilic C−H fluorination has progressed much more slowly, a state of play explaining why C−H 18F‐fluorination is still in its infancy.
The direct fluorination of C−H bonds has emerged as a powerful method for accessing functional molecules such as pharmaceuticals or PET radiotracers. This Review provides an overview of the state of play of this field with an emphasis on the advantages and limitations of the main activation modes exploited to date. The discussion brings to light the importance of the fluorination reagent, and the challenges associated with nucleophilic C−H fluorination methods.
Printable elastic conductors promise large-area stretchable sensor/actuator networks for healthcare, wearables and robotics. Elastomers with metal nanoparticles are one of the best approaches to ...achieve high performance, but large-area utilization is limited by difficulties in their processability. Here we report a printable elastic conductor containing Ag nanoparticles that are formed in situ, solely by mixing micrometre-sized Ag flakes, fluorine rubbers, and surfactant. Our printable elastic composites exhibit conductivity higher than 4,000 S cm
(highest value: 6,168 S cm
) at 0% strain, and 935 S cm
when stretched up to 400%. Ag nanoparticle formation is influenced by the surfactant, heating processes, and elastomer molecular weight, resulting in a drastic improvement of conductivity. Fully printed sensor networks for stretchable robots are demonstrated, sensing pressure and temperature accurately, even when stretched over 250%.
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•The concept of fluorine doped carbon is proposed;•Polyvinylidene fluoride is used as carbon and fluoride source;•The optimal LFP@F-doped carbon nanocomposites delivered a practical ...capacity and cyclability.
The present work presents an insightful study on the effect of fluorine doped carbon (FC) modification on the electrochemical performance of LiFePO4 cathode material. To this end, polyvinylidene fluoride is used as fluoride source to synthesize FC, which is designed to coat on LiFePO4 surface with formation of LiFePO4@FC nanocomposites. The microstructure and electrochemical properties of the nanocomposites are systematically examined by various characterization techniques, revealing that FC is tightly attached on surface of LiFePO4 particles forming a three dimensional (3D) conductive network structure. Such favorable structure provides advantages of good grain-to-grain electrical contact, shortening the Li+ diffusion distance between the grain interfaces, and facilitating the rapid transfer of electrons during charge–discharge. The optimal LiFePO4@FC nanocomposites, i.e., with 97.2 wt% of LiFePO4, are verified to show highly desirable electrochemical performance with superior rate capability and excellent cycling performance as the cathode material of lithium-ion batteries.
Der vorliegende Aufsatz diskutiert die jüngsten Entwicklungen in der Forschung zu Grenzflächenphänomenen fluorierter Amphiphile und konzentriert sich auf Anwendungen, die die einzigartigen und ...vielfältigen Grenzflächeneigenschaften dieser Amphiphile ausnutzen. Vor allem bilden fluorierte Amphiphile stabile Aggregate mit oft deutlich anderer Morphologie als ihre nicht fluorierten Analoga. Folglich finden fluorierte Tenside vielfältigen Einsatz in Hochleistungsanwendungen wie dem Mikrofluidik‐unterstützten Screening. Darüber hinaus wird ihr fluorspezifisches Verhalten an der Fest/Flüssig‐Grenzfläche thematisiert, wie zum Beispiel die Bildung superhydrophober Beschichtungen nach der Abscheidung auf Oberflächen. Da fluorierte Tenside und perfluorierte Materialien im Allgemeinen potenzielle Umweltbedrohungen darstellen, werden auch die jüngsten Entwicklungen der Schadstoffsanierung durch ihre Adsorption an fluorierte Oberflächen bewertet.
Fluorierte Amphiphile zeigen Grenzflächeneigenschaften, die sich deutlich von denen gewöhnlicher nichtfluorierter Amphiphile unterscheiden, wie einzigartige, stark verzweigte Überstrukturen und eine bessere Stabilisierung von Mikrotröpfchen. Weitere fluorspezifische Phänomene fluorierter Amphiphile können an Fest/Flüssig‐Grenzflächen beobachtet werden, wie z. B. bei ihrer Adsorption an fluorierten Adsorbermaterialien oder bei der Bildung amphiphober Oberflächenbeschichtungen nach der Vernetzung.
Incubations with pure and enrichment cultures of Acidimicrobium sp. strain A6 (A6), an autotroph that oxidizes ammonium to nitrite while reducing ferric iron, were conducted in the presence of PFOA ...or PFOS at 0.1 mg/L and 100 mg/L. Buildup of fluoride, shorter-chain perfluorinated products, and acetate was observed, as well as a decrease in Fe(III) reduced per ammonium oxidized. Incubations with hydrogen as a sole electron donor also resulted in the defluorination of these PFAS. Removal of up to 60% of PFOA and PFOS was observed during 100 day incubations, while total fluorine (organic plus fluoride) remained constant throughout the incubations. To determine if PFOA/PFOS or some of their degradation products were metabolized, and since no organic carbon source except these PFAS was added, dissolved organic carbon (DOC) was tracked. At concentrations of 100 mg/L, PFOA/PFOS were the main contributors to DOC, which remained constant during the pure A6 culture incubations. Whereas in the A6 enrichment culture, DOC decreased slightly with time, indicating that as defluorination of PFOS/PFOA occurred, some of the products were being metabolized by heterotrophs present in this culture. Results show that A6 can defluorinate PFOA/PFOS while reducing iron, using ammonium or hydrogen as the electron donor.
Thiophene and its derivatives have been extensively used in organic electronics, particularly in the field of polymer solar cells (PSCs). Significant research efforts have been dedicated to modifying ...thiophene-based units by attaching electron-donating or withdrawing groups to tune the energy levels of conjugated materials. Herein, we report the design and synthesis of a novel thiophene derivative, FE-T, featuring a monothiophene functionalized with both an electron-withdrawing fluorine atom (F) and an ester group (E). The FE-T unit possesses distinctive advantages of both F and E groups, the synergistic effects of which enable significant downshifting of the energy levels and enhanced aggregation/crystallinity of the resulting organic materials. Shown in this work are a series of polymers obtained by incorporating the FE-T unit into a PM6 polymer to fine-tune the energetics and morphology of this high-performance PSC material. The optimal polymer in the series shows a downshifted HOMO and an improved morphology, leading to a high PCE of 16.4% with a small energy loss (0.53 eV) enabled by the reduced non-radiative energy loss (0.23 eV), which are among the best values reported for non-fullerene PSCs to date. This work shows that the FE-T unit is a promising building block to construct donor polymers for high-performance organic photovoltaic cells.
Both fluorine and ester substituted monothiophene yielded a novel thiophene derivative FE-T. The resulting polymer donor S1 enabled single-junction non-fullerene solar cell with over 16% efficiency.
Redoxaktive N‐(Fluormethoxy)benzotriazole wurden aus Fluoressigsäure und Hydroxybenzotriazolen durch elektrocarboxylative Kopplung zugänglich gemacht. Nach Alkylierung werden diese zu wirksamen ...Monofluormethoxylierungsreagenzien, welche die photokatalytische C‐H‐Funktionalisierung von Aromaten ermöglichen. Dadurch kann durch Bestrahlung von 1‐(OCH2F)‐3‐Me‐6‐(CF3)benzotriazoliumtriflat mit blauem LED‐Licht in Gegenwart von Ru(bpy)3(PF6)2 die Synthese von vielfältig funktionalisierten Arylmonofluormethylethern begünstigt werden. Diese Methode ermöglicht die späte Funktionalisierung biologisch relevanter Strukturen, ohne auf ökologisch problematische Halofluorkohlenwasserstoffe angewiesen zu sein.
Eine neue Klasse von N‐OCH2F‐redoxaktiven Reagenzien wurde durch elektrocarboxylative C(sp3)O‐Kopplung von N‐Hydroxybenzotriazolen mit Fluoressigsäure und anschließender Alkylierung synthetisiert. Durch Bestrahlung mit blauen LEDs in Gegenwart eines Photosensibilisators ermöglichen diese lagerstabilen Reagenzien die Synthese von Monofluormethylarylethern durch Funktionalisierung von C‐H‐Bindungen.
Further enhancement in the energy densities of rechargeable lithium batteries calls for novel cell chemistry with advanced electrode materials that are compatible with suitable electrolytes without ...compromising the overall performance and safety, especially when considering high‐voltage applications. Significant advancements in cell chemistry based on traditional organic carbonate‐based electrolytes may be successfully achieved by introducing fluorine into the salt, solvent/cosolvent, or functional additive structure. The combination of the benefits from different constituents enables optimization of the electrolyte and battery chemistry toward specific, targeted applications. This Review aims to highlight key research activities and technical developments of fluorine‐based materials for aprotic non‐aqueous solvent‐based electrolytes and their components along with the related ongoing scientific challenges and limitations. Ionic liquid‐based electrolytes containing fluorine will not be considered in this Review.
Opposites attract and complement: Lithium and fluorine are long‐term partners in energy storage systems, especially in Li‐based battery technologies, as they enable further improvements in energy and power density as well as enhancing life span and safety. This Review discusses key research and technical developments for the broad application of F‐based materials for liquid electrolytes in Li‐based batteries as well as related ongoing scientific challenges.
Heteroatom modification represents one of the largest studied areas of research related to nanostructured carbon materials, with integrated applications stretching from energy production and storage ...to sustainability and medical uses. While a wide variety of dopants (boron, phosphorus, iodine, fluorine,
etc.
) have been studied, doping carbon structures with nitrogen ad-atoms has arguably experienced the greatest progress and brought the most attention over the last several years. Research in this field has conclusively demonstrated that nitrogen doping is an effective way to tailor the properties of carbon and tune the material for various applications of interest. This review provides a comprehensive overview of advances in the last half decade on state-of-the-art carbon modification with nitrogen heteroatoms. Improvements in well-established fabrication/modification processes are discussed as well as novel strategies. Additionally, recent theoretical and experimental findings related to the benefits and effects of nitrogen modification for specific applications in the energy and environmental fields are reviewed.
Nitrogen modification of carbon structures is making a vast impact across the scientific community, specifically in the realms of energy and sustainability.
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