Selective bottom-up synthesis of carbon materials with a reactive C–H bond adjacent to pyridinic nitrogen from brominated fused bicyclic aromatic compounds

Carbon materials containing pyridinic nitrogen have been reported to exhibit high catalytic and electrode performance. Especially, a C-H group adjacent to pyridinic nitrogen (N-SOLO) has been reported to act as an active site for oxygen reduction reaction for fuel cells. However, for mass production of carbon materials with such structures, precise structural control should be conducted without using metal catalysts. In this study, brominated precursors with two fused rings were utilized as precursors of carbon materials to increase the percentages of both pyridinic nitrogen and N-SOLO simultaneously without using metal catalysts. Heat treatment of 3,7-dibromo-1,5-naphthyridine at 623 K yielded 76% pyridinic nitrogen (N content: 11 at.%) with 74% N-SOLO/SOLO, which is the highest percentage of N-SOLO/SOLO in carbon materials ever obtained without using catalysts. Screening of precursors by density functional theory calculations and molecular dynamics simulations with a reactive force field (Reax FF) revealed that 3,7-dibromo-1,5-naphthyridine tended to form a high percentage of pyridinic nitrogen because of the small percentage of formed tertiary nitrogen. Furthermore, N-SOLO exhibited the highest occupied orbital energy among various C-H groups adjacent to pyridinic nitrogen such as N-SOLO, N-DUO, and N-TRIO, suggesting that N-SOLO is the most active site among N-SOLO, N-DUO, and N-TRIO.