Pyridine-appended 5,6-open-aza[60]fulleroid can act as a unique host for alcohols

Abstract

Pyridine-appended 5,6-open-aza[60]fulleroid (2) and 6,6-closed-aza[60]fullerene (3) were synthesised for the first time. It was found that 2, in which the aza group conjugates with the [60]fulleroid π-system, can bind certain alcohols via a hydrogen-bonding interaction and shows high selectivity towards methanol. In contrast, 3, in which the aza group does not conjugate with the [60]fullerene π-system, scarcely shows such an alcohol affinity. The results indicate that a slight difference in the arrangement of the nitrogens results in a drastic change in the guest affinity. The guest-binding processes were thoroughly investigated by UV–Vis absorption and NMR spectroscopic methods and electrochemical methods. This is a unique neutral guest recognition system utilising the [60]fullerene surface.