Coronene fusion by heat treatment: Road to nanographenes

Abstract

The reactions of coronene dehydrogenation and fusion upon heat treatment in the temperature range of 500-700°C were studied using XRD, TEM, Raman, IR, and NEXAFS spectroscopy. The formation of a coronene dimer (dicoronylene) was observed at temperatures 530-550°C; dicoronylene can easily be separated using sublimation with a temperature gradient. An insoluble and not sublimable black precipitate was found to form at higher temperatures. Analysis of the data shows that dimerization of coronene is followed at 550-600°C by oligomerization into larger molecules. Above 600°C amorphization of the material and formation of graphitic nanoparticles was observed. Coronene fusion by annealing is proposed as a road to synthesis of larger polycyclic aromatic hydrocarbons and nanographenes. © 2011 American Chemical Society.