Solvent-free pathways towards carbon nanomaterials
Polycylic aromatic hydrocarbons (PAHs), nanographenes and graphene nanoribbons are promising materials with potential applications in organic and nano-electronics. During the bottom-up synthesis of the latter the Scholl reaction, a Lewis-acid catalyzed oxidative cyclodehydrogenation is utilized to planarize precursor systems by forming aryl-aryl bonds and creating a fully pi-conjugated material. Especially for the larger precrusors solubility is a main concern but even the smallest planarized hexabenzocoronene (HBC) is almost insoluble in common organic solvents even at elevated temperatures. The common workaround is the introduction of solubilizing groups. Thereby additional synthesis steps are required and the atom economy of the process suffers, hindering the scale-up needed for industrial applications.
If solubilty is the problem - Mechanochemistry is the solution!
We recently developed a radical new approach towards the planarization of nanographenes utilizing a mechanochemical Scholl reaction. Our approach is displaying a tremendous advance in terms of both ecological and economic aspects, since the mechanochemical synthesis requires neither hazardous solvents nor harsh reaction conditions and can be conducted within a short time scale. Moreover, our synthetic pathway excels in scalability and versatility significantly broadening the synthetic prospects towards larger extended nanographenes.