Radical organometallic nanocages with redox switchable poly-NHC ligands

Developing discrete radical organometallic nanocages is essential for fabricating functional materials. In this study, we construct a series of poly-NHC-based (NHC = N-heterocyclic carbene) organometallic nanocages 3a–3c with different sizes by employing redox-active bis(triarylamine) derivatives with different π-conjugated spacers as building blocks. The varied sizes of nanocages 3a–3c modulate the distance of the redox-active centers and reversibly convert them to radical nanocages 3a²⁺–3c²⁺ through chemical and electrochemical oxidation. Radical nanocages 3a²⁺–3c²⁺ display clear bond and angle alteration and retention of their three-dimensional topologies. This work not only merely proves that these nanocages are excellent stimulus-responsive materials but also opens a door to the rational design of novel radical organometallic nanocages.