Inserting Porphyrin Quantum Dots in Bottom-Up Synthesized Graphene Nanoribbons

Diels–Alder copolymerization of tetraphenylcyclopentadienone, a precursor for cove graphene nanoribbons (cGNRs), with bifunctional porphyrins yields defined nanostructures comprised of a single cGNR‐porphyrin‐cGNR heterojunction within each ribbon. 13C NMR labeling and high‐resolution mass spectrometry of solubilized polymer intermediates indicates that every porphyrin is covalently linked to two extended segments of cGNRs. UV/Vis absorption and fluorescence emission spectroscopy reveal a strong electronic correlation between the porphyrin and the adjacent cGNR segments that can be attenuated through reversible metalation of the porphyrin core. This versatile bottom‐up synthetic strategy provides access to structurally well‐defined, functional GNR‐quantum dot‐GNR heterostructures within a single graphene nanoribbon.