A fluorescent calixarene-based dimeric capsule constructed via a M II -terpyridine interaction: cage structure, inclusion properties and drug release.

Two analogues of capsule-like fluorescent cages have been constructed by dimerization of terpyridine-containing calixarene derivatives utilizing a M II -terpyridine (M = Zn and Cd) interaction. 1 H NMR spectral studies show that the self-assembled molecular capsules Zn 4 L1 2 and Cd 4 L1 2 have a highly symmetrical D 4h -structure. The encapsulation of the anticancer drug mercaptopurine in their cavities has been documented by NMR, ESI-TOF-MS, fluorescence switching, and molecular simulation, indicating that strong S-π and π-π interactions between drug and cage are of importance for the host-guest binding. The nanoscale cages exhibit excellent behaviors to control the release of mercaptopurine in phosphate buffered saline solution (pH = 7.4). These results further highlight the potential of self-assembled Zn 4 L1 2 cages for drug-carrier applications.