Dendritic amphiphiles have emerged as supramolecular building blocks of particular interest for applications in pharmaceuticals, catalysis, or the controlled synthesis of nanostructured materials. Common supramolecular structures for chiral amphiphiles are twisted ribbons, wound ribbons, or helically structured tubes.
Christoph Böttcher, Freie Universität Berlin, Germany, and colleagues have designed and synthesized nonionic chiral (R,R and S,S) and achiral (R,S) dendritic amphiphiles with polyglycerols as the hydrophilic part, a diaromatic spacer, and hydrophobic hexadecyl chains.
The team studied the impact of the stereochemistry of the pure compounds and racemate on the assembly behavior using cryogenic transmission electron microscopy (cryo-TEM) and circular dichroism (CD) spectroscopy, which revealed profound differences in aggregation behavior. They observed right-/left-handed twisted ribbons for chiral gels, uniform cylinders and disk-like structures for the meso-form, and stacks of planar platelets for the racemic mixture.
Based on these results, the researchers hope to understand the molecular parameters that define supramolecular assembly behavior, leading to the rational design of chiral gels for selective interaction with chiral host molecules.
- Introducing Chirality into Nonionic Dendritic Amphiphiles and Studying Their Supramolecular Assembly,
Sumit Kumar, Kai Ludwig, Boris Schade, Hans von Berlepsch, Ilona Papp, Rahul Tyagi, Monika Gulia, Rainer Haag, Christoph Böttcher,
Chem. Eur. J. 2016.