Cover Picture: Bioavailability of Metallic Impurities in Carbon Nanotubes Is Greatly Enhanced by Ultrasonication (Chem. Eur. J. 37/2012)
2012; Wiley; Volume: 18; Issue: 37 Linguagem: Inglês
10.1002/chem.201290158
ISSN1521-3765
AutoresRou Jun Toh, Adriano Ambrosi, Martin Pumera,
Tópico(s)Catalytic C–H Functionalization Methods
ResumoUltrasonication is a common procedure in the treatment of carbon nanotubes. Ultrasound carves carbon nanotubes, making toxic metallic impurities more accessible, in a similar manner the silent wind carves sand from the sandstone of Antelope Canyon, Arizona. For more details, see the Full Paper by M. Pumera et al. on page 11593 ff. Oxidative Carbocyclizations Palladium-catalyzed oxidative carbocyclization reactions and their applications to total synthesis have attracted considerable attention in recent years. Through the development of efficient palladium catalysts and oxidation systems, various intra- and intermolecular carbon–carbon bond-coupling reactions are now available. See the Review by J.-E. Bäckvall et al. on page 11498 ff. for some of the latest developments in this field.1 Metallocycles Taking advantage of the coordination strength of a ruthenium(II) bisterpyridine complex, G. Newkome, C. Wesdemiotis, A. Schultz, and co-workers in their Communication on page 11569 ff. have successfully synthesized a series of novel tetrameric macrocycles based on a 60°-oriented bisterpyridine ligand, resulting in folded architectures. Resembling the graceful giant manta ray, these folded metallomacrocycles, termed Dondorff rings after the first to report these rays, were characterized photophysically, as well as by ESI-TWIM-MS and molecular modeling.1 Asymmetric Catalysis Additive effects of amines were investigated in asymmetric hydrogenation of 2-substituted quinoxalines catalyzed by an air-stable chiral dinuclear triply-halide-bridged iridium complex. Catalytic reactivity and enantioselectivity were dramatically improved by an addition of amine. A mechanistic study revealed a dual mechanism that involved two individual catalytic cycles in equilibrium. The product amine itself could enhance catalytic activity and enantioselectivity during the reaction course, demonstrating the first positive feedback enhancement in asymmetric hydrogenation. For more information see the Full Paper by K. Mashima et al. on page 11578 ff. 1
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