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. ¹³ C 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.