Our work on the “Metallobuckytrios” (MBTs), that consists the effort of over three years, from many group members and collaborators, has been accepted for publication by Angewandte Chemie!
Congratulations to first author Dr. Yanbang Li, now a researcher at Kyoto University. Also shout out to the great contribution from Rohin Biswas, William Kopcha, Yue Sun and Ryan Crichton. Finally, we sincerely thank our collaborators in the groups of Profs. Ki-Bum Lee, Josep Poblet, Antonio Rodriguez-Fortea, Stephen Hill.
Endohedral Metallofullerenes have been promised as a great platform for the development of rare-earth element (REE) based metallodrugs, such as (gadolinium-based) MRI contrast agents, because they can definitively seal the toxic heavy metal ions inside a cage, have precise structures, and are susceptible to organic functionalization with robust C-C bonds. However, existing approaches to synthesize water-soluble EMF derivatives mainly focused on solubility, and they yield mixtures of inhomogeneous number of hydrophilic groups (e.g., -OH, -COOH) with almost random regiochemical locations on the cage. This would significantly compromise characterization and quality control of the resulting hydrophilic EMF derivatives, and inhibit precise drug design. In this work, we report the synthesis of metallobuckytrio (MBT), a three-buckyball system, as a modular platform to develop structurally defined water-soluble EMF derivatives with ligands by choice. Demonstrated with PEG ligands, the resulting water-soluble MBTs show superb biocompatibility. The Gd MBTs exhibit superior T1 relaxivity than typical Gd complexes, potentially superseding current clinical MRI contrast agents in both safety and efficiency. The Lu MBTs generated reactive oxygen species upon light irradiation, showing promise as photosensitizers. With their modular nature to incorporate other ligands, we anticipate the MBT platform to open new paths towards bio-specific REE drugs.