Fully Collapsed Imploded Cryptophanes in Solution and in the Solid State

Cryptophanes with flexible linkers derived from (±)‐tris‐(4‐formyl‐phenyl)‐cyclotriguaiacylene with either bisoxydi(ethylamine) or bis(aminopropyl)ether were isolated as single crystals, the crystal structures of which showed the proposed, but previously uncharacterised, out‐in conformation, in which both cyclotriguaiacylene fragments adopt a crown conformation with one crown sitting inside the other. The usual cage‐like out‐out conformation of the cryptophanes was observed when crystals were dissolved upon heating, and the molecules collapsed back to the out‐in isomers over time. In contrast, a cryptophane also derived from (±)‐tris‐(4‐formyl‐phenyl)‐cyclotriguaiacylene but with rigid dibenzalhydrazine linkers was isolated as the more usual out‐out isomer. Out‐in! Two cryptophanes have been shown to adopt the completely collapsed out‐in conformation with all cyclotribenzylenes groups in the bowl‐like crown conformation. Remarkably, the more common cage‐like out‐out conformation is initially observed upon dissolution at high temperature, and the cage implodes even in the presence of potential guest molecules.