Titanium-Oxide Host Clusters with Exchangeable Guests

This is the authors' abstract. We don't add key points for this paper.

A novel family of water-soluble, polyoxocationic titanium-oxide host–guest clusters are reported herein. They exhibit an unprecedented hexagonal prismatic core structure for hosting univalent cationic guests like K +, Rb +, Cs + and H 3 O + . Guest exchange has been studied using 133 Cs NMR, showing the flexible pore of a host permits passage of a comparatively larger cation and giving an equilibrium constant of ca. 13 for displacing Rb + by Cs + . Attractive ion-dipole interaction, depending on host–guest size complementarity, plays a dominant role for the preferential encapsulation of larger alkali-metal cationic guests.