Rational Control of Self-Recognition of Macroionic γ-Cyclodextrin by Host-Guest Interaction with Super-Chaotropic Borate Cluster Ions

We report a feasible method to control self-recognition during the self-assembly of a hydrophilic macroion, phosphate-functionalized gamma-cyclodextrin (gamma-CD-P), though host-guest interactions. We confirmed that gamma-CD-P can form a host-guest complex with a super-chaotropic anion, namely the B12F122- borate cluster, by using NMR spectroscopy and isothermal titration calorimetry. The loaded gamma-CD-P, which has a higher charge density, can be distinguished from the uncomplexed gamma-CD-P, leading to self-sorting behavior during the self-assembly process, confirmed by the formation of two types of individual supramolecular structures (R-h of ca. 57 nm and 18 nm, determined by light scattering) instead of hybrid structures in mixed dilute solution. This self-recognition behavior is accounted for by the difference in intermolecular electrostatic interactions arising from the loading.