Enhanced host-guest interaction between [10]cyclopara-phenylene ([10]CPP) and [5]CPP by cationic charges

A dication of [5]cycloparaphenylene ([5]CPP2+) was selectively encapsulated by neutral [10]CPP to form the shortest double-layercarbon nanotube, [10]CPP superset of[5]CPP2+. While the same host-guest complex consisted of neutral CPPs, [10]CPP superset of[5]CPP, wasalready reported, the cationic complex showed an about 20 times higher association constant in (CDCl2)2 at 25 degrees C (103 mol L-1).Electrochemical and photophysical analyses and theoretical calculations suggested the partial electron transfer from [10]CPP to[5]CPP2+ in the complex, and this charge-transfer (CT) interaction is most likely the origin of the higher association constant of thedicationic complex than the neutral one