TEMPO was immobilized on continuous-flow-optimized mesoporous silica particles and a TEMPO/DAIB mediated oxidation followed by Knoevenagel condensation was investigated.
SummaryA common approach to generate tailored materials and nanoparticles (NPs) is the formation of molecular monolayers by chemisorption of bifunctional anchor molecules. This approach depends critically on the choice of a suitable anchor group. Recently, bifunctional catecholates, inspired by mussel-adhesive proteins (MAPs) and bacterial siderophores, have received considerable interest as anchor groups for biomedically relevant metal surfaces and nanoparticles. We report here the synthesis of new tripodal catecholates as multivalent anchor molecules for immobilization on metal surfaces and nanoparticles. The tripodal catecholates have been conjugated to various effector molecules such as PEG, a sulfobetaine and an adamantyl group. The potential of these conjugates has been demonstrated with the immobilization of tripodal catecholates on ZnO NPs. The results confirmed a high loading of tripodal PEG-catecholates on the particles and the formation of stable PEG layers in aqueous solution.
We present an optimized procedure for the synthesis of (S)-vinylglycine from (S)-methionine. The key step is a solvent free pyrolysis of an intermediate sulfoxide at high temperature. Using our optimized reaction conditions, Cbz-protected vinylglycine was obtained in high yield and with almost no side products. The protocol is scalable, fast and avoids the use of poisonous reagents.
Poly(divinylbenzene) (PDVB) nanofibers are synthesized by electrospinning dispersions of PDVB nanoparticles (diameter 40–90 nm) derived by miniemulsion polymerization. Interparticle crosslinking is achieved by addition of a radical starter after electrospinning endowing the fibers with high solvent‐stability. The fibers exhibit a Brunauer–Emmett–Teller (BET) surface area in the range of ≈30–70 m2 g−1 due to internal mesoporosity, which originates from the interparticle space. Spinning parameters like the concentrations of spin polymer and nanoparticles, as well as the nanoparticle diameter, are systematically varied to investigate the influence of these parameters on the mesopore structure. The fiber morphology is studied by scanning electron microscopy and the mesopore size, volume, and BET surface area are determined by nitrogen physisorption measurements. The findings indicate that the pore size mainly depends on the PDVB nanoparticle diameter. As a main finding, the fiber diameter can be adjusted by the concentration of spin polymer or nanoparticles without changing the mesopore diameter. Chlorine‐functionalized fibers are synthesized by electrospinning of poly(divinylbenzene‐co‐4‐vinylbenzyl chloride) nanoparticle dispersions. Chlorine groups are further used for the covalent immobilization of an organocatalyst (2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO)).
Front Cover: In article number https://doi.org/10.1002/macp.201700471 by Bernd M. Smarsly and co‐workers, porous polymer fibers are obtained by electrospinning poly(divinylbenzene) nanoparticle dispersion. The nanoscaled porosity can be controlled by the particle size, and the impact of several spinning parameters on the porosity is studied. Such particle‐based fibers can potentially be used for anchoring organocatalysts, as exemplified by the functionalization with the organocatalyst (4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl, 4‐hydroxy‐TEMPO).
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