Tiny chemical cages created by researchers at
These cage-like molecules, called nanocontainers or nanoscale capsules because they measure 3.2 nanometres wide, could also make pesticides less hazardous to handle, filter toxic substances out of wastewater and regulate the pace of reactions in chemical production.
“While the concept of chemical cages is not new, we’ve created new components and advanced the assembly process to increase the chance that they’ll become practical,” said Ralf Warmuth, associate professor of chemistry and chemical biology at
Warmuth and colleagues used common organic chemicals and straightforward techniques to create nanocontainers. These octahedral capsules, with their cavity volume of almost two cubic nanometres, could enclose one or more molecules of a medicine, pesticide or intermediate in a chemical manufacturing process that, if left uncaged, might prematurely decay or interact with other substances in passing.
Previous techniques for assembling molecular cages involved tradeoffs. With one approach, the synthesis technique was straightforward, but the pieces of the molecular cages were not bound as tightly to each other. Another approach resulted in tighter bonds, but the process required several carefully orchestrated steps. The
Atoms at four sites along each bowl’s rim bond to atoms on the ends of the bridges. The atomic structure and properties of these molecules ensure that they naturally assemble themselves into capsules and do so with high yield when combined in proper proportions.
Early research suggests that the connections between the bridges and bowls can be broken and reattached under controlled conditions to introduce “payload” molecules – such as a drug or pesticide – into the cage and extract them when needed.