Mini polymeric tubes separate enantiomers

Separations using tiny polymer-based devices could offer an alternative to chromatography for purifying of chiral compounds . Serena Arnaboldi of the University of Milan and coworkers initially reported the tubular devices late last year ( Chem 2023, DOI: 10.1016/j.chempr.2023.11.001 ), and the team has now shown that the devices can isolate enantiomers of multiple compounds in a single sample ( Anal. Chem. 2024, DOI: 10.1021/acs.analchem.3c05544 ). The tubes are about 1 cm long and 300 μm in diameter, and they feature a two-layer structure. The inner tubular layer, which is made of a chiral oligomer, interacts with the molecules in a sample as they flow through the tube. That interaction—in which the oligomer grips one enantiomer more strongly than the other—gives the device its separation power. The outer layer, which is made of polypyrrole, pumps the sample through the tube. The pumping action stems from polypyrrole's ion-exchange properties: they make