Introducing Chirality into Nonionic Dendritic Amphiphiles and Studying Their Supramolecular Assembly

• Published in: Chemistry : a European journal Vol. 22; no. 16; pp. 5629 - 5636
• Main Authors: Kumar, Sumit, Ludwig, Kai, Schade, Boris, von Berlepsch, Hans, Papp, Ilona, Tyagi, Rahul, Gulia, Monika, Haag, Rainer, Böttcher, Christoph
• Format: Journal Article
• Language: English
• Published: WEINHEIM Blackwell Publishing Ltd 11.04.2016; Wiley; Wiley Subscription Services, Inc
• Subjects: Aggregates; amphiphiles; Assembly; Chemistry; Chemistry, Multidisciplinary; chirality; Electrons; Elongation; Enantiomers; Handedness; helical structures; Nonionic; Physical Sciences; Platelets; Ribbons; scanning probe microscopy; Science & Technology; self-assembly; SYSTEM; amphiphiles; DESIGN; chirality; helical structures; RESOLUTION; MICELLES; TRANSMISSION ELECTRON-MICROSCOPY; ORGANIZATION; self-assembly; scanning probe microscopy; CHEMISTRY; ARCHITECTURES; WATER
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201504504

Chiral head groups have been introduced into water‐soluble hydroxyl‐terminated nonionic amphiphiles and the impact of the head group stereochemistry on the supramolecular ultrastructures has been studied. Enantiomeric isomers were compared with the achiral meso form and the racemic mixture by means of cryogenic transmission electron microscopy and circular dichroism spectroscopy. Structurally, all amphiphiles are composed of the first‐generation hydrophilic polyglycerol head group coupled to a single hydrophobic hexadecyl chain through an amide linkage and diaromatic spacer. The enantiomers aggregate to form twisted ribbons with uniform handedness, whereas the meso stereoisomer and racemic mixture produce elongated assemblies, namely, tubules and platelets, but without a chiral ultrastructure. Simulations on the molecular packing geometries of the stereoisomers indicate different preferential assembly routes that explain the individual supramolecular aggregation behavior. Changing twists: Chiral head groups have been introduced into water‐soluble hydroxyl‐terminated nonionic amphiphiles. The enantiomers aggregate to form twisted ribbons with counter‐rotating handedness, whereas the meso stereoisomer and racemic mixture produce elongated assemblies, namely, tubules and platelets, but without a chiral ultrastructure (see figure).