Polish scientists have made a molecular container that can encapsulate molecules and differentiate between their enantiomers. 

Agnieszka Szumna and Bogumil Kuberski at the Polish Academy of Sciences, Warsaw, made the container from vase-shaped molecules called resorcinarenes substituted with amino acid molecules. They showed that when two resorcinarene molecules come together, they form a chiral capsule with a non-polar exterior and a polar, amino acid-functionalised interior. 

Scientists are interested in molecular containers because their interior can mimic the active sites of natural proteins. Reactions inside molecular containers can also be faster than normal reactions because the effective concentration of reactants is greater. But until now, most molecular containers have had smooth (non-chiral), non-polar interiors that have limited their selectivity and activity. 

'Our capsule can be considered as a kind of molecular reversed micelle,' says Szumna. 'It can perform some simple functions: it is able to extract from the water phase and encapsulate biologically relevant polar molecules and differentiate between their enantiomers.' 

Szumna says the most challenging problem they are working on is effective asymmetric synthesis within molecular containers. Until now, most of the reactions carried out in molecular containers have not been asymmetric. 'In our system, promising functional groups protrude the interior; amino acids' amino groups are known to take part in natural and artificial organocatalytic reactions,' says Szumna. 'Although there are many problems to overcome, we hope that the "inversed capsules" will be able to form as reaction vessels as well.' 

Joanne Thomson