Scorpionate Hydrotris(indazolyl)borate Ligands as Tripodal Platforms for Surface-Mounted Molecular Gears and Motors
Résumé
This microreview describes the use of scorpionate hydrotris(indazolyl)borate ligands to build structurally rigid bifunctional surface-mounted molecular gears or motors. The article starts with the synthesis of 6-functionalized indazoles and their corresponding scorpionate tris(indazolyl)borate tripodal ligands. Thioether groups allow the tripodal anchoring of such ligands on metallic surfaces, whereas ester functions enable anchoring on insulating surfaces. Finally, we present their coordination to ruthenium penta(aryl)cyclopentadienyl fragments for the preparation of prototypes of molecular gears and motors. The synthesis of the tetraferrocenylruthenium complex, a molecular motor that has been shown to exhibit controlled clockwise or anticlockwise unidirectional rotation, is also detailed.