Doped melamine crystals have been synthesized by crystallinzation of melamine in aqueous THF with various concentrations of TCNE. For more detail see the SI. Figure inset shows the micrographs of the crystals prepared by mixing 0.1 M aqueous solution of melamine and aqueous THF solutions of TCNE with a concentration of 0.0002 (bottom left) and 0.02 M (bottom right).