Unique cation binding capability of cyclic oligo(l-lactic acid) (l-COLA)
Cyclic l-lactic acid octamer (l-COLA-8) shows a unique complexing capability towards alkali and alkali earth metal cations in acetonitrile-d3/chloroform-d (9/1). The valence of the cation affects the stoichiometry of the complexes between l-COLA-8 and the cation; l-COLA-8 forms a 2:1 complex with alkali metal cations, but forms a 1:1 complex with alkali earth metal cations. Additionally, l-COLA-8 shows a binding selectivity for Rb+ and Ba2+, which have a diameter about 3 Å.
Kogame, C., Kida, T., Fujiwara, T., & Akashi, M. (2015). Unique cation binding capability of cyclic oligo(l-lactic acid) (l-COLA). Tetrahedron Letters, 56 (13), 1675-1678. https://doi.org/10.1016/j.tetlet.2015.02.037