Supramolecular coronation of platinum(II) complexes by macrocycles: Structure, relativistic DFT calculations, and biological effects

Platinum-based anticancer drugs are actively developed utilizing lipophilic ligands or drug carriers for the efficient penetration of biomembranes, reduction of side effects, and tumor targeting. We report the development of a supramolecular host–guest system built on cationic platinum(II) compounds bearing ligands anchored in the cavity of the macrocyclic host. The host–guest binding and hydrolysis process on the platinum core were investigated in detail by using NMR, MS, X-ray diffraction, and relativistic DFT calculations. The encapsulation process in cucurbit[7]uril unequivocally promotes the stability of hydrolyzed dicationic cis-[PtII(NH3)2(H2O)(NH2-R)]2+ compared to its trans isomer. Biological screening on the ovarian cancer lines A2780 and A2780/CP shows time-dependent toxicity. Notably, the reported complex and its β-cyclodextrin (β-CD) assembly achieve the same cellular uptake as cisplatin and cisplatin@β-CD, respectively, while maintaining a significantly lower toxicity profile