On-Surface Synthesis of Nanographenes and Graphene Nanoribbons on Titanium Dioxide

The formation of two types of nanographenes from custom designed and synthesized molecular precursors has been achieved through thermally induced intramolecular cyclodehydrogenation reactions on the semiconducting TiO2(110)-(1x1) surface, confirmed by the combination of spectroscopy (STS) measurements, and corroborated by theoretical modeling. The application of this protocol on differently shaped molecular precursors demonstrates the ability to induce a highly efficient planarization reaction both within strained pentahelicenes as well as between vicinal phenyl rings. Additionally, by the combination of successive Ullmann-type polymerization and cyclodehydrogenation reactions, the archetypic 7-armchair graphene nanoribbons (7-AGNRs) have also been fabricated on the titanium dioxide surface from the standard 10,10 '-dibromo-9,9 '-bianthryl (DBBA) molecular precursors. These examples of the effective cyclodehydrogenative planarization processes provide perspectives for the rational design and synthesis of molecular nanostructures on semiconductors.

Automated summary

The formation of two types of nanographenes from custom-designed and synthesized molecular precursors has been achieved through intramolecular cyclodehydrogenation reactions on the TiO2 surface. Confirmation was made through spectroscopy measurements and theoretical modeling. Additionally, archetypic 7-armchair graphene nanoribbons have also been fabricated on the titanium dioxide surface through successive polymerization and cyclodehydrogenation reactions. These processes provide new perspectives for the rational design and synthesis of molecular nanostructures on semiconductors.