Platforms for Stable Carbon-Centered Radicals

Organic radicals can potentially play important roles in functional materials owing to an unpaired electron, but they are usually highly reactive and difficult to use. Therefore, stabilization of organic radicals is important. Among organic radicals, carbon-centered radicals are promising because of their trivalent nature, which enables structural diversity and elaborate designs, but they are also less stable because of the reactivities towards carbon-carbon bond formation and atmospheric oxygen. Recently, stable carbon-centered radicals across diverse molecular platforms have been increasingly explored. This Minireview highlights these newly explored, stable carbon-centered radicals, with a focus on porphyrinoid-stabilized radicals because of their remarkable spin delocalization abilities.