Cationic triphenylphosphinegold(I) complexes are excellent catalysts for a cascade reaction of propargyl-Claisen rearrangement and heterocyclization to synthesize tri- and tetrasubstituted furans. Starting from easily accessed propargyl vinyl ethers, the furans are obtained in 72-99% yield. [reaction: see text]

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Novel α,ω‐functionalized amphiphilic lipopolymers are prepared that are composed of a proximal lipid moiety and a hydrophilic poly(2‐oxazoline)‐based (POx) polymer chain. The synthesis begins from bifunctional lipoinitiators, which are asymmetrically protected as tert.butyldiphenylsilyl (TBDPS) ethers, followed by cationic living ring‐opening polymerization of 2‐oxazolines in a one‐pot multistep reaction. This results in polymers with defined terminal end groups and narrow molar mass distributions. All protective groups involved can be readily cleaved in a single step reaction keeping the structure of the polymer intact, giving access to (lipo)polymers with a variety of defined identical or chemical orthogonal α,ω‐functionalities. The synthetic strategy is a versatile tool for the preparation of defined polymer–drug or polymer–protein conjugates or asymmetric functionalized model lipid membranes for the quantitative study of membrane‐associated phenomena such as transmembrane transport and cell adhesion/recognition.

Hydrated polymer interlayers between planar lipid membranes and solid substrates provide a water reservoir and thus maintain a finite membrane-substrate distance. Linear polymer spacers attached to lipid head groups (lipopolymer tethers) can be used as a defined model of oligo- and polysaccharides covalently anchored on cell surfaces (glycocalyx). They can offer a unique advantage over membranes physisorbed on polymer films (called polymer-cushioned membranes), owing to their ability to control both the length and density of polymer chains. In this study, a lipopolymer tether composed of a stable ether lipid moiety and a hydrophilic poly(2-methyl-2-oxazoline) spacer with a length of 60 monomer units is used to fabricate supported membranes by the successive deposition of proximal (lower) and distal (upper) leaflets. Using specular X-ray reflectivity and ellipsometry, we systematically investigate how the lateral density of polymer chains influences the membrane-substrate interactions. The combination of two types of reflectivity techniques under various conditions enables the calculation of quantitative force-distance relationships. Such artificial membrane systems can be considered as a half-model of cell-cell contacts mediated via the glycocalyx, which reveals the influence of polymer chain density on the interplay of interfacial forces at biological interfaces.

We study the formation of dissipative microstructures in monomolecular films of surfactant mixtures, which occur near the three-phase contact line during Langmuir-Blodgett transfer onto a solid substrate. Continuous stripes parallel to the transfer direction are generated over several centimeters, indicating the phase separation of phospholipids and lipids with polymer head groups (lipopolymers). The systematic variation of transfer conditions revealed that transfer speed and subphase viscosity determine the stripe-to-stripe distance from several micrometers to submicrometers. To account for the physical mechanism of such pattern formation, we characterize the local film thickness and the membrane composition in the vicinity of the three-phase contact line using imaging ellipsometry and fluorescence microscopy. At relatively slow rates of substrate lifting, the power law exponent that we found between the interstripe distance and the transfer speed suggests that the stripe formation is due to spinodal decomposition, which can be accounted under the framework of the Cahn-Hilliard equation, whereas at relatively high rates, the distance is found to be proportional to the substrate speed, suggesting a dominant effect of the shear force on the stripe formation.