Polymerization of Brominated Aromatic Compounds within a Metal-Organic Framework toward Bottom-up Synthesis of Graphene Nanoribbons with Either Pyridinic or Tertiary Nitrogen

Abstract

Graphene nanoribbons (GNRs) have attracted attention because of their adjustability of bandgap depending on the width and the edge shape. Introducing nitrogen into GNRs has been reported to further improve the optical, electronic, catalytic, and magnetic properties. Therefore, the large-scale synthesis of GNRs with controlled nitrogen-containing functional groups is in demand, but the mass synthesis is challenging because metal substrates, which work as catalysts, are essential for the synthesis, and the removal of the catalysts is required. In this study, GNRs with either pyridinic nitrogen or tertiary nitrogen were synthesized by carbonizing brominated bicyclic aromatic compounds with pyridinic nitrogen as precursors in the nano space of metal-organic frameworks (MOF). The use of MOF increased not only the synthesized amount but also the percentage of either pyridinic nitrogen (+13% (from 38 to 51%)) or tertiary nitrogen (+26% (from 9 to 35%)). Also, results of experimental X-ray photoelectron and infrared spectra in addition to molecular dynamics simulation with a reactive force field implied the presence of GNR-like structures with either pyridinic nitrogen or tertiary nitrogen in the samples prepared at 673 K. Thus, this study provides precious data for the mass synthesis of GNRs with either pyridinic nitrogen or tertiary nitrogen.