Chirality transfer through multistep reaction processes towards the synthesis of enantiopure chiral graphene nanoribbons*

Besides its interest for potential optoelectronic devices, molecular chirality is of utmost importance in biology and medicine. Consequently relevant is the selective synthesis of enantiopure molecular compounds, which has been hardly addressed in the growing field of “on-surface synthesis”. In this frame, 2,2′-dibromo-9,9′-bianthracene reactants are known to form chiral graphene nanoribbons (GNR) on coinage metal substrates through a complex multi-step reaction including an initial radical step growth polymerization by Ullmann coupling and following cyclodehydrogenation steps. In this work we show how, starting from enantiopure reactants deposited onto Au(111), their chirality is sequentially transferred to the polymers and finally to the GNRs with an excellent level of selectivity. Unambiguous evidence of this effect is obtained by high-resolution scanning tunneling microscopy images.