Defined micelles: A completely uniform and structurally precise micelle spontaneously formed by exactly seven amphiphilic dendro‐calixarene molecules in aqueous solution has been determined by cryo‐TEM and 3D reconstruction techniques. The picture shows seven calixarene head groups, which have been fit visually into the reconstructed density map of the micelle.

The highly charged amphiphilic dendron-calixarene (1) forms stable monolayers at the air-water interface. Crystallization of CaCO 3 beneath monolayers of 1 selectively leads to growth of the metastable polymorph vaterite at low surface pressure, in distinct contrast to the growth characteristics of calcite or aragonite crystals under less highly charged calixarene monolayers, as we have reported previously. This result lends further support to our hypothesis that surface charge density is the dominant factor governing heterogeneous nucleation of CaCO 3 crystals at the monolayer/solution interface.

Eine runde Sache: Eine einheitliche und strukturtreue Micelle bildet sich spontan aus sieben amphiphilen Calixarendendrimer‐Molekülen. Ihre Struktur wurde durch Kryo‐Transmissionselektronenmikroskopie und Techniken zur dreidimensionalen Rekonstruktion bestimmt. Das Bild zeigt sieben Kopfgruppen des Amphiphils, die visuell in die rekonstruierte Dichtekarte der Micelle eingepasst wurden.

The formation of micelles of an amphiphilic dendro-calixarene (1) was studied using pyrene as a guest molecule. Steady-state fluorescence experiments were performed, which showed that pyrene is readily solubilized in the micelles and senses an environment with a moderate polarity. Time-resolved fluorescence measurements showed that pyrene in the micelles have two lifetimes, suggesting some compartmentalization of the guest within the micelles. Pyrene bound to the micelles is completely protected from the interaction with anionic species in the aqueous phase, due to the repulsion between the anions and the negatively charged micelles. Compared to conventional micelles, such as those formed with sodium dodecyl sulfate, micelles of 1 form at much lower concentrations of monomer.

Die definierte Struktur von Micellen die durch Selbstorganisation amphiphiler Dendrocalixarene in wässriger Lösung entstehen, zeigt die dreidimensionale Rekonstruktion auf dem Titelbild. Wie A. Hirsch, C. Böttcher und Mitarbeiter in ihrer Zuschrift auf S. 3019 ff. berichten, führt die starre T‐Struktur der Moleküle zu einer effizienten Rückfaltung unter Bildung der stark gekrümmten Aggregate. Dank der Formtreue dieser Nanocontainer gelang die strukturelle Charakterisierung einer micellaren Architektur mit molekularer Auflösung.

The exceptional structure of the first reconstructed micelles is formed by the selfassembly of amphiphilic dendrocalixarenes in aqueous solution. A. Hirsch, C. Böttcher, and co-workers report in their Communication on page 2959 ff. that the relatively rigid T-shaped structure of the molecule allows efficient backfolding and thus the formation of aggregates with high curvature. Structural determination of the nanocontainers permits characterization of the micellar architecture at the molecular level.