Magnetovulkametrische Untersuchung der Vernetzung von ungesättigten Polymeren mit Peroxiden

Zusammenfassung Durch Messung der Drehung eines im Polymer eingebetteten Weicheisenstäbchens im Magnetfeld (Magnetovulkametrie) werden die Vernetzung von 1,4-Polybutadien und Styrol/Butadien-Kautschuk mit Dicumylperoxid sowie die Vernetzung von Naturkautschuk (1,4-Polyisopren) mit tert-Butylperbenzoat in Abwesenheit von Additiven und in Anwesenheit von Harnstoff, Anilin und Benzylamin untersucht.Herrn Prof. Dr. Dr. h. c. W. Kern zum 75. Geburtstag gewidmet.     

Room‐Temperature‐Phosphorescence‐Based Dissolved Oxygen Detection by Core‐Shell Polymer Nanoparticles Containing Metal‐Free Organic Phosphors

The highly sensitive optical detection of oxygen including dissolved oxygen (DO) is of great interest in various applications. We devised a novel room‐temperature‐phosphorescence (RTP)‐based oxygen detection platform by constructing core–shell nanoparticles with water‐soluble polymethyloxazoline shells and oxygen‐permeable polystyrene cores crosslinked with metal‐free purely organic phosphors. The resulting nanoparticles show a very high sensitivity for DO with a limit of detection (LOD) of 60 nm and can be readily used for oxygen quantification in aqueous environments as well as the gaseous phase.     

Fluorescent Isoindole Crosslink (FlICk) Chemistry: A Rapid,User‐friendly Stapling Reaction

The stabilization of peptide secondary structure via stapling is a ubiquitous goal for creating new probes, imaging agents, and drugs. Inspired by indole‐derived crosslinks found in natural peptide toxins, we employed ortho‐phthalaldehydes to create isoindole staples, thus transforming inactive linear and monocyclic precursors into bioactive monocyclic and bicyclic products. Mild, metal‐free conditions give an array of macrocyclic α‐melanocyte‐stimulating hormone (α‐MSH) derivatives, of which several isoindole‐stapled α‐MSH analogues (K_i≈1 nm ) are found to be as potent as α‐MSH. Analogously, late‐stage intra‐annular isoindole stapling furnished a bicyclic peptide mimic of α‐amanitin that is cytotoxic to CHO cells (IC₅₀=70 μm ). Given its user‐friendliness, we have termed this approach FlICk (fluorescent isoindole crosslink) chemistry.