Fjord-Edge Graphene Nanoribbons with Site-Specific Nitrogen Substitution

The
synthesis of graphene nanoribbons (GNRs) that contain site-specifically
substituted backbone heteroatoms is one of the essential goals that
must be achieved in order to control the electronic properties of
these next generation organic materials. We have exploited our recently
reported solid-state topochemical polymerization/cyclization-aromatization
strategy to convert the simple 1,4-bis­(3-pyridyl)­butadiynes 3a,b into the fjord-edge nitrogen-doped graphene nanoribbon
structures 1a,b (fjord-edge N2[8]­GNRs). Structural
assignments are confirmed by CP/MAS 13C NMR, Raman, and
XPS spectroscopy. The fjord-edge N2[8]­GNRs 1a,b are promising precursors for the novel backbone nitrogen-substituted
N2[8]AGNRs 2a,b. Geometry and band
calculations on N2[8]AGNR 2c indicate
that this class of nanoribbons should have unusual bonding topology
and metallicity.