Nonaggregational Shape-Persistent Cyclo[6]aramide and Its Macrocyclic Effect toward Binding Secondary Ammonium Salts in Moderately Polar Media

Simply by introducing steric side chains, the shape-persistent cyclo[6]aramides were found to exhibit nonaggregational behavior and strong association (3 × 10(4) M(-1)) ability in acetone for binding secondary ammonium salt. The complexation can be switched in an on-and-off fashion using AgPF6 and TBACl, contrasting sharply with their corresponding acyclic pentamer and demonstrating the macrocyclic effect.