Oxidative cleavage of vicinal diols catalyzed by monomeric Fe‐sites inside MFI zeolite

The oxidative cleavage of vicinal diols to carboxylic acids was investigated over heterogeneous Fe/MFI catalysts in aqueous medium, with green oxidant H2O2 and in mild reaction conditions. High conversions and selectivities (X=90 %, S=79 %) were achieved for the oxidative cleavage of ethylene glycol. Further substrates were also tested broadening the relevance of this catalyst. The employment of non-noble and abundant Fe as the active metal and the MFI-type zeolite as support has a clear advantage over the presently used homogeneous or noble metal-based catalysts. A combination of complementary characterisation techniques with catalytic results is used to show that monomeric Fe species inside zeolite MFI are the active sites for the oxidative cleavage of C−C bonds of vicinal diols. The recyclability of the catalyst and reaction mechanism were also studied

Dual sequence definition increases the data storage capacity of sequence-defined macromolecules

Sequence-defined macromolecules offer applications in the field of data storage. Challenges include synthesising precise and pure sequences, reading stored information and increasing data storage capacity. Herein, the synthesis of dual sequence-defined oligomers and their application for data storage is demonstrated. While applying the well-established Passerini three-component reaction, the degree of definition of the prepared monodisperse macromolecules is improved compared to previous reports by utilising nine specifically designed isocyanide monomers to introduce backbone definition. The monomers are combined with various aldehyde components to synthesise dual-sequence defined oligomers. Thus, the side chains and the backbones of these macromolecules can be varied independently, exhibiting increased molecular diversity and hence data storage capacity per repeat unit. In case of a dual sequence-defined pentamer, 33 bits are achieved in a single molecule. The oligomers are obtained in multigram scale and excellent purity. Sequential read-out by tandem ESI-MS/MS verifies the high data storage capacity of the prepared oligomers per repeat unit in comparison to other sequence defined macromolecules

Leistungen des ökologischen Landbaus für Umwelt und Gesellschaft - Kontext, Zielsetzung und Vorgehen

Obwohl die Umweltauswirkungen des ökologischen Landbaus wissenschaftlich und politisch allgemein anerkannt sind, gibt es immer noch unterschiedliche Ansichten, wie der Beitrag des ökologischen Landbaus zur Lösung der Umwelt- und Ressourcenprobleme unserer Zeit bewertet werden kann. Dieser Beitrag beschreibt Hintergrund und Inhalt dieser Debatte und beschreibt den Ansatz zur Analyse des aktuellen Forschungsstandes