Nano-scale design of novel stationary phases to enhance selectivity for molecular shape and size in liquid chromatography

The design of novel stationary phases in liquid chromatography (LC) which offer enhanced selectivity or better resolution of fullerenes is described. Fullerene molecules have been chosen due to their recent popularity and importance in both chemistry and the materials science fields. From the previous studies on octadecyl modified silica (ODS) stationary phases in LC an important structural requirement for stationary phases that can effectively separate fullerenes has been identified. The distance between each bonded functional group on the silica surface that is best-fit to the fullerene diameter (e.g. C₆₀ has ca. 7 Å diameter and inter-ligand distance 7.1 Å of ODS phase is the best-fit size) is the key to improve the separation performance. A phenyl ligand contribution to fullerenes retention has also been found to be important. The size and shape of the cavity-like multilegged phenyl bonded phases is the dominant parameter for the structural recognition of fullerenes. By utilizing these factors a novel stationary phase structure is proposed.