Arene Ruthenium Cages: Boxes Full of Surprises

Self-assembly of polypyridyl ligands with dinuclear arene ruthenium building blocks bridged by chlorido, oxalato or benzoquinonato ligands has allowed the construction of a wide range of cationic metalla complexes possessing different architectures and functionalities: (i) metalla-rectangles showing host-guest possibilities and allowing intramolecular template-controlled photochemical [2 + 2] dimerisation reactions; (ii) metalla-prisms allowing encapsulation of molecules and giving rise to potential drug delivery systems; (iii) metalla-boxes that can be used to stabilise the formation of G-quadruplex DNA. This microreview covers the synthetic and structural aspects of these metalla complexes, as well as their most promising applications, with a particular focus on their potential biological applications.