Researchers in the Netherlands have made a supramolecular capsule that they say has the makings of a nano-sized reaction chamber. 

Joost Reek and colleagues at the University of Amsterdam have created a supramolecular capsule composed of two complementary building blocks: a tetraanionic calixarene and a tetracationic, functionalised diphosphine ligand.  These molecules self-assemble reversibly, using non-covalent interactions, to form a cavity that hosts a reactive palladium centre.

The palladium coordinates to the diphosphine group, remaining active because it is not involved in the self-assembly process.  Reek's group showed that the palladium keeps its activity by performing a CO-insertion reaction at the metal centre, and found that the capsule remains intact throughout the process. 

According to Reek, there is great interest in the synthesis of these structures and their use as nano-sized reaction chambers. 

The challenge now is 'to use the cavities of these new metallo-hetero capsules as chambers for transition metal catalyzed reactions,' he said.

Alison Stoddart