Redox-active benzoquinones as challenging “non-innocent” linkers to construct 2D frameworks and nanostructures with tunable physical properties

Exploiting redox activity in supramolecular frameworks such as coordination polymers, metal-organic frameworks and related nanostructures is of paramount importance both at the molecular level and for their technological applications, since the modulation of their redox states is an emerging strategy to enhance their physical properties. In the plethora of organic linkers, quinone derivatives are excellent redox-active ligands, widely used for various applications such as electrode materials, flow batteries, pseudocapacitors, etc. Benzoquinones undergo a one-electron reversible reduction to form a semiquinone radical species that can be further reduced to form hydroquinone. Remarkably, the quinoid ring can be functionalized with various functional groups making these systems excellent linkers to construct supramolecular frameworks as well as challenging platforms to tune the redox potential and therefore the stability of radical anions and electrochemical performances of the obtained materials. The recent advances on benzoquinone-based 2D CPs/MOFs and related nanostructures are reported, highlighting the extreme versatility of this class of redox-active linkers in tailoring the physical properties of the obtained materials. The current/future potential of these materials in electrochemical and technologically relevant applications will also be envisioned.