A hunter hunted! A highly preorganized, deep metallocavitand of nanoscale dimensions containing rhenium atoms at the four corners can be readily synthesized from a simple formyl‐substituted calix[4]arene and 3,8‐phenanthroquinone. Unsubstituted calix[4]arenes and cavitands without substituents on the lower rim are the ideal guests for such an expanded calixarene (see picture), and are included with binding constants of 103–105 M−1.

Vom Jäger zum Gejagten: Ein präorganisierter tiefer Metallocavitand mit Rheniumatomen an seinen vier Ecken wurde aus einem formylierten Calix[4]aren und 3,8‐Phenanthrochinon synthetisiert. Unsubstituierte Calix[4]arene und Cavitanden ohne Substituenten am unteren Rand sind ideale Gastspezies für dieses expandierte Calixaren (siehe Bild), das sie mit Bindungskonstanten von 103–105 M−1 einschließt.

A neutral metallo-cavitand based on cis bis-perhaloaryl Pd(II) bridges co-ordinated at the corners of a deep calix[4]arene. Both the metallo-cavitand and its inclusion complexes with other calix[4]arenes were investigated by means of (1)H and (19)F NMR experiments.

Fressen und gefressen werden ist ein Prinzip, das nicht nur in der Natur, sondern auch in dem Wirt‐Gast‐System zu finden ist, das J. de Mendoza et al. in der Zuschrift auf S. 202 ff. beschreiben und in dem ein Wirt (kleinere Calix[4]arene und Cavitanden) selbst zur “Beute” eines noch größeren Wirtes wird (eines Metallocavitanden aus einem Calix[4]aren mit durch Re‐Atome verbundenen [3,8]Phenanthrolin‐Untereinheiten). Das Titelbild zeigt die Komplexierung eines Cavitanden (von P. Ballester) vor einer Unterwasseraufnahme am Cap Andritxol auf Mallorca (von E. Botana).

Hunter and hunted is not only a principle of nature but is also found in host-guest systems. J. de Mendoza and co-workers describe in their Communication on page 198 ff. how a host molecule (a small calix[4]arene or cavitand) can itself become the "prey" for a larger host (a metallocavitand made from a calix[4]arene with [3,8]phenanthroline subunits linked through Re atoms). The cover picture shows the complexation of a cavitand (by P. Ballester) superimposed on an underwater picture at Cap Andritxol, Mallorca (by E. Botana). Renewable EnergiesEnergy is the most important issue of the 21st century. In their Essay on page 52 ff., N. Armaroli and V. Balzani discuss the impending energy crisis and the fundamental challenges we face both as scientists and as responsible citizens. Molecular DevicesThe underlying principles for the design of synthetic molecular machines is described by D. A. Leigh and co-workers in their Review on page 72 ff. The progress made towards utilizing the machines to perform tasks is also highlighted. Helical NanotubesIn their Communication on page 194 ff., J. K. M. Sanders and co-workers show that the helical chirality of nanotubes formed by amino acid derivatives of naphthalenediimide is determined by the constituent amino acid but is independent of the nature of the side chains.