Giant regular polyhedra from calixarene carboxylates and uranyl

Self-assembly of large multi-component systems is a common strategy for the bottom-up construction of discrete, well-defined, nanoscopic-sized cages. Icosahedral or pseudospherical viral capsids, built up from hundreds of identical proteins, constitute typical examples of the complexity attained by biological self-assembly. Chemical versions of the so-called 5 Platonic regular or 13 Archimedean semi-regular polyhedra are usually assembled combining molecular platforms with metals with commensurate coordination spheres. Here we report novel, self-assembled cages, using the conical-shaped carboxylic acid derivatives of calix[4]arene and calix[5]arene as ligands, and the uranyl cation UO22+ as a metallic counterpart, which coordinates with three carboxylates at the equatorial plane, giving rise to hexagonal bipyramidal architectures. As a result, octahedral and icosahedral anionic metallocages of nanoscopic dimensions are formed with an unusually small number of components

Calixarene complexes of anion-bridged oligouranyl species

The syntheses and structures of uranyl complexes of p-t-Bu-calix[6]arene (calix[6]H6) and p-t-Bu-calix[9]arene(calix[9]H9) are reported, further developing the role of calixarenes as 'cluster keepers'. The calix[6]arene com-plex, formulated as [(HO){UO2(calix[6]H4)(dmso)}3H], is trinuclear and linked symmetrically by the hydroxyl O atom. The calix[9]arene complex is binuclear, with a carbonate atom bridging between the two uranyl cations to give the complex, (HNEt3)3[(OCO2)(UO2)3(calix[9]H4)]

L’entrée en scène

« La plupart des artistes de théâtre, et beaucoup de metteurs en scène en premier lieu, reconnaissent que l’entrée en scène, ses modalités, sa dramaturgie, est un acte décisif : il engage tout le spectacle à venir, il détermine sa réception, il éveille la sensibilité du spectateur, et conditionne donc son intelligence. » Jean-Loup Rivière, Entrée libr