TY - JOUR AB - The influence of structural modifications on the catalytic activity of carbon materials is poorly understood. A collection of carbonaceous materials with different pore networks and high nitrogen content was characterized and used to catalyze four reactions to deduce structure–activity relationships. The CO2 cycloaddition and Knoevenagel reaction depend on Lewis basic sites (electron-rich nitrogen species). The absence of large conjugated carbon domains resulting from the introduction of large amounts of nitrogen in the carbon network is responsible for poor redox activity, as observed through the catalytic reduction of nitrobenzene with hydrazine and the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine using hydroperoxide. The material with the highest activity towards Lewis acid catalysis (in the hydrolysis of (dimethoxymethyl)benzene to benzaldehyde) is the most effective for small molecule activation and presents the highest concentration of electron-poor nitrogen species. AU - Lepre, Enrico AU - Rat, Sylvain AU - Cavedon, Cristian AU - Seeberger, Peter H. AU - Pieber, Bartholomäus AU - Antonietti, Markus AU - López‐Salas, Nieves ID - 12922 IS - 2 JF - Angewandte Chemie International Edition KW - General Chemistry KW - Catalysis SN - 1433-7851 TI - Catalytic properties of high nitrogen content carbonaceous materials VL - 62 ER - TY - GEN AB - Cover Page AU - Becker, Lea Marie AU - Berbon, Mélanie AU - Vallet, Alicia AU - Grelard, Axelle AU - Morvan, Estelle AU - Bardiaux, Benjamin AU - Lichtenecker, Roman AU - Ernst, Matthias AU - Loquet, Antoine AU - Schanda, Paul ID - 14861 IS - 19 KW - General Chemistry KW - Catalysis SN - 1433-7851 T2 - Angewandte Chemie International Edition TI - Cover Picture: The rigid core and flexible surface of amyloid fibrils probed by Magic‐Angle‐Spinning NMR spectroscopy of aromatic residues VL - 62 ER - TY - JOUR AB - The short history of research on Li-O2 batteries has seen a remarkable number of mechanistic U-turns over the years. From the initial use of carbonate electrolytes, that were then found to be entirely unsuitable, to the belief that (su)peroxide was solely responsible for degradation, before the more reactive singlet oxygen was found to form, to the hypothesis that capacity depends on a competing surface/solution mechanism before a practically exclusive solution mechanism was identified. Herein, we argue for an ever-fresh look at the reported data without bias towards supposedly established explanations. We explain how the latest findings on rate and capacity limits, as well as the origin of side reactions, are connected via the disproportionation (DISP) step in the (dis)charge mechanism. Therefrom, directions emerge for the design of electrolytes and mediators on how to suppress side reactions and to enable high rate and high reversible capacity. AU - Jethwa, Rajesh B AU - Mondal, Soumyadip AU - Pant, Bhargavi AU - Freunberger, Stefan Alexander ID - 14687 JF - Angewandte Chemie International Edition KW - General Chemistry KW - Catalysis SN - 1433-7851 TI - To DISP or not? The far‐reaching reaction mechanisms underpinning Lithium‐air batteries ER - TY - JOUR AB - Aromatic side chains are important reporters of the plasticity of proteins, and often form important contacts in protein--protein interactions. By studying a pair of structurally homologous cross-β amyloid fibrils, HET-s and HELLF, with a specific isotope-labeling approach and magic-angle-spinning (MAS) NMR, we have characterized the dynamic behavior of Phe and Tyr aromatic rings to show that the hydrophobic amyloid core is rigid, without any sign of "breathing motions" over hundreds of milliseconds at least. Aromatic residues exposed at the fibril surface have a rigid ring axis but undergo ring flips, on a variety of time scales from ns to µs. Our approach provides direct insight into hydrophobic-core motions, enabling a better evaluation of the conformational heterogeneity generated from a NMR structural ensemble of such amyloid cross-β architecture. AU - Becker, Lea Marie AU - Berbon, Mélanie AU - Vallet, Alicia AU - Grelard, Axelle AU - Morvan, Estelle AU - Bardiaux, Benjamin AU - Lichtenecker, Roman AU - Ernst, Matthias AU - Loquet, Antoine AU - Schanda, Paul ID - 12675 IS - 19 JF - Angewandte Chemie International Edition KW - General Chemistry KW - Catalysis SN - 1433-7851 TI - The rigid core and flexible surface of amyloid fibrils probed by Magic‐Angle Spinning NMR of aromatic residues VL - 62 ER - TY - JOUR AB - Covalent organic frameworks (COFs) are structurally tuneable, porous and crystalline polymers constructed through the covalent attachment of small organic building blocks as elementary units. Using the myriad of such building blocks, a broad spectrum of functionalities has been applied for COF syntheses for broad applications, including heterogeneous catalysis. Herein, we report the synthesis of a new family of porous and crystalline COFs using a novel acridine linker and benzene-1,3,5-tricarbaldehyde derivatives bearing a variable number of hydroxy groups. With the broad absorption in the visible light region, the COFs were applied as photocatalysts in metallaphotocatalytic C−N cross-coupling. The fully β-ketoenamine linked COF showed the highest activity, due to the increased charge separation upon irradiation. The COF showed good to excellent yields for several aryl bromides, good recyclability and even catalyzed the organic transformation in presence of green light as energy source. AU - Traxler, Michael AU - Gisbertz, Sebastian AU - Pachfule, Pradip AU - Schmidt, Johannes AU - Roeser, Jérôme AU - Reischauer, Susanne AU - Rabeah, Jabor AU - Pieber, Bartholomäus AU - Thomas, Arne ID - 11955 IS - 21 JF - Angewandte Chemie International Edition SN - 1433-7851 TI - Acridine‐functionalized covalent organic frameworks (COFs) as photocatalysts for metallaphotocatalytic C−N cross‐coupling VL - 61 ER -