Macrocycles inserted in graphene: from coordination chemistry on graphene to graphitic carbon oxide

Tuning electronic structures and properties through chemical modifications has become the focus of recent research on graphene. The adsorption of metal atoms on graphene showed strong potential but is limited due to weak binding. On the other hand, macrocyclic molecules are well known for their strong and selective binding with metal atoms in solutions through coordination bonds. The alliance of the two substances will largely benefit the two parallel fields: it will provide a scaffold for coordination chemistry as well as a controllable method for tuning the electronic structure of graphene through strong binding with metals. Here, using crown ether as an example, we demonstrate that the embedment of macrocyclic molecules into the graphene honeycomb lattice can be very thermochemically favored. The combination also leads to a family of new materials that has potential in many areas including photolysis and two-dimensional superconductivity.