Anion Exchange Membranes for Fuel Cells: State‐of‐the‐Art and Perspectives

Advanced Energy Materials, Год журнала: 2022, Номер 12(28)

Опубликована: Июнь 2, 2022

Abstract Fuel cell technology is a clean way of generating energy and should enable carbon neutrality. However, although traditional proton exchange membrane fuel cells (PEMFCs) have made commercial impact, their high cost hinders wider adoption. that use anion membranes (AEMs) are promising alternative to PEMFCs, as they can achieve the same performance at lower cost. In this Perspective, recent trends in fabrication polymer‐based high‐performance AEMs highlighted future directions identified. Since ensuring durability polymers strong alkaline conditions most critical issue development AEM cells, strategies for formation with chemical stability, mechanical ionic conductivity primarily focused on. Successes polymer design expected inaugurate next generation trigger fresh wave innovation, leading long‐lasting reduce emissions facilitate sustainable development.

Язык: Английский

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Cobalt-Catalyzed Enantioselective C–H Arylation of Indoles

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(2), С. 798 - 806

Опубликована: Янв. 10, 2022

Atropoisomeric (hetero)biaryls are scaffolds with increasing importance in the pharmaceutical and agrochemical industries. Although it is most obvious disconnection to construct such compounds, direct enantioselective C–H arylation through concomitant induction of chiral information remains extremely challenging uncommon. Herein, unprecedented earth-abundant 3d-metal-catalyzed atroposelective reported, furnishing rare atropoisomeric C2-arylated indoles. Kinetic studies DFT computation revealed an uncommon mechanism for this asymmetric transformation, oxidative addition being rate- enantio-determining step. Excellent stereoselectivities were reached (up 96% ee), while using unusual N-heterocyclic carbene ligand bearing essential remote substituent. Attractive dispersion interactions along positive C–H---π exerted by identified as key factors guarantee excellent enantioselection.

Язык: Английский

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Transition-metal-catalyzed C–H bond alkylation using olefins: recent advances and mechanistic aspects

Chemical Society Reviews, Год журнала: 2022, Номер 51(17), С. 7358 - 7426

Опубликована: Янв. 1, 2022

Transition metal catalysis has contributed immensely to C-C bond formation reactions over the last few decades, and alkylation is no exception. The superiority of such methodologies traditional evident from minimal reaction steps, shorter times, atom economy while also allowing control regio- stereo-selectivity. In particular, hydrocarbonation alkenes grabbed increased attention due its fundamental ability effectively selectively synthesise a wide range industrially pharmaceutically relevant moieties. This review attempts provide scientific viewpoint systematic analysis recent developments in transition-metal-catalyzed various C-H bonds using simple activated olefins. key features mechanistic studies involved these transformations are described briefly.

Язык: Английский

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Cobalt(III)/Chiral Carboxylic Acid‐Catalyzed Enantioselective Synthesis of Benzothiadiazine‐1‐oxides via C−H Activation

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(28)

Опубликована: Май 2, 2022

Abstract Among sulfoximine derivatives containing a chiral sulfur center, benzothiadiazine‐1‐oxides are important for applications in medicinal chemistry. Here, we report that the combination of an achiral cobalt(III) catalyst and pseudo‐ C 2 ‐symmetric H 8 ‐binaphthyl carboxylic acid enables asymmetric synthesis from sulfoximines dioxazolones via enantioselective C−H bond cleavage. With optimized protocol, with several functional groups can be accessed high enantioselectivity.

Язык: Английский

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Electrooxidative palladium- and enantioselective rhodium-catalyzed [3 + 2] spiroannulations

Chemical Science, Год журнала: 2022, Номер 13(9), С. 2783 - 2788

Опубликована: Янв. 1, 2022

Despite indisputable progress in the development of electrochemical transformations, electrocatalytic annulations for synthesis biologically relevant three-dimensional spirocyclic compounds has as yet not been accomplished. In sharp contrast, herein, we describe palladaelectro-catalyzed C-H activation/[3 + 2] spiroannulation alkynes by 1-aryl-2-naphthols. Likewise, a cationic rhodium(iii) catalyst was shown to enable electrooxidative [3 spiroannulations via formal C(sp3)-H activations. The versatile featured broad substrate scope, employing electricity green oxidant lieu stoichiometric chemical oxidants under mild conditions. An array enones and diverse spiropyrazolones, bearing all-carbon quaternary stereogenic centers were thereby accessed user-friendly undivided cell setup, with molecular hydrogen sole byproduct.

Язык: Английский

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Enzymatic Nitrogen Insertion into Unactivated C–H Bonds

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(41), С. 19097 - 19105

Опубликована: Окт. 4, 2022

Selective functionalization of aliphatic C–H bonds, ubiquitous in molecular structures, could allow ready access to diverse chemical products. While enzymatic oxygenation bonds is well established, the analogous nitrogen still unknown; nature reliant on preoxidized compounds for incorporation. Likewise, synthetic methods selective derivatization unbiased remain elusive. In this work, new-to-nature heme-containing nitrene transferases were used as starting points directed evolution enzymes selectively aminate and amidate unactivated C(sp3)–H sites. The desymmetrization methyl- ethylcyclohexane with divergent site selectivity offered demonstration. evolved these lineages are highly promiscuous show activity toward a wide array substrates, providing foundation further transferase function. Computational studies kinetic isotope effects (KIEs) consistent stepwise radical pathway involving an irreversible, enantiodetermining hydrogen atom transfer (HAT), followed by lower-barrier diastereoselectivity-determining rebound step. In-enzyme dynamics (MD) simulations reveal predominantly hydrophobic pocket favorable dispersion interactions substrate. By offering direct path from saturated precursors, present new biochemical logic accessing nitrogen-containing compounds.

Язык: Английский

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Diversification of Glycosyl Compounds via Glycosyl Radicals

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(38)

Опубликована: Июнь 7, 2023

Glycosyl radical functionalization is one of the central topics in synthetic carbohydrate chemistry. Recent advances metal-catalyzed cross-coupling chemistry and metallaphotoredox catalysis provided powerful platforms for glycosyl diversification. In particular, discovery new precursors conjunction with these advanced reaction technologies have significantly expanded space compound synthesis. this Review, we highlight most recent progress area starting from 2021, reports included will be categorized based on different types better clarity.

Язык: Английский

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Waste to energy: Trending key challenges and current technologies in waste plastic management

The Science of The Total Environment, Год журнала: 2023, Номер 913, С. 169436 - 169436

Опубликована: Дек. 29, 2023

Due to the 'forever' degrading nature of plastic waste, waste management is often complicated. The applications are ubiquitous and inevitable in many scenarios. Current global plastics production ca. 3.5 MMT per year, with current trend, will reach 25,000 by 2040. However, rapid growth manufacture material's inherent resulted accumulation a vast amount garbage. recycling rate <10 %, while large volumes discarded cause environmental ecological problems. Recycling rates for vary widely region type plastic. In some developed countries, around 20-30 developing nations, it much lower. These statistics highlight magnitude problem urgent need comprehensive strategies manage more effectively reduce its impact on environment. This review critically analyses past studies essential efficient techniques turning trash into treasure. Additionally, an attempt has been made provide understanding upcycling process, 3Rs policy, life-cycle assessment (LCA) conversion. advocates pyrolysis as one most promising methods valuable chemicals. addition, can be severely impacted due uncontrollable events, such Covid 19 pandemic. chemical certainly bring value end-of-life LCA analysis indicated there still huge scope innovation area compared mechanical recycling. formulation policies heightened public participation could play pivotal role reducing repercussions facilitating shift towards sustainable future.

Язык: Английский

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Enroute sustainability: metal free C–H bond functionalisation

Chemical Society Reviews, Год журнала: 2023, Номер 52(7), С. 2391 - 2479

Опубликована: Янв. 1, 2023

The metal-free C–H functionalisation is providing environmentally benign, cost-effective, sustainable catalytic systems. Comprehensive developments of various reactions are the focal point this review.

Язык: Английский

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Palladium (II)‐Catalyzed C−H Activation with Bifunctional Ligands: From Curiosity to Industrialization

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(19)

Опубликована: Фев. 29, 2024

Abstract In 2001, our curiosity to understand the stereochemistry of C−H metalation with Pd prompted first studies in Pd(II)‐catalyzed asymmetric activation (RSC Research appointment: 020 7451 2545, Grant: RG 36873, Dec. 2002). We identified four central challenges: 1. poor reactivity simple salts native substrates; 2. few strategies control site selectivity for remote bonds; 3. lack chiral catalysts achieve enantioselectivity via metalation, and 4. low practicality due limited coupling partner scope use specialized oxidants. These challenges necessitated new catalyst reaction development. For , we developed approaches enhance substrate–catalyst affinity together novel bifunctional ligands which participate accelerate cleavage step. site‐selectivity introduced concept systematically modulating distance geometry between a directing template, catalyst, substrate selectively access bonds. devised predictable stereomodels catalyst‐controlled enantioselective based on participation ligands. Finally, have varied catalytic manifolds Pd(II) accommodate diverse partners while employing practical oxidants such as peroxides. advances culminated numerous reactions, setting stage broad industrial applications.

Язык: Английский

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