RESUMO
Fine management of chiral processes on solid surfaces has progressed over the years, yet still faces the need for the controlled and selective production of advanced chiral materials. Here, we report on the use of enantiomerically enriched molecular building blocks to demonstrate the transmission of their intrinsic chirality along a sequence of on-surface reactions. Triggered by thermal annealing, the on-surface reactions induced in this experiment involve firstly the coupling of the chiral reactants into chiral polymers and subsequently their transformation into planar prochiral graphene nanoribbons. Our study reveals that the axial chirality of the reactant is not only transferred to the polymers, but also to the planar chirality of the graphene nanoribbon end products. Such chirality transfer consequently allows, starting from adequate enantioenriched reactants, for the controlled production of chiral and prochiral organic nanoarchitectures with pre-defined handedness.
RESUMO
The forces between two single molecules brought into contact, and their connection with charge transport through the molecular junction, are studied here using non contact AFM, STM, and density functional theory simulations. A carbon monoxide molecule approaching an acetylene molecule (C_{2}H_{2}) initially feels weak attractive electrostatic forces, partly arising from charge reorganization in the presence of molecular . We find that the molecular contact is chemically passive, and protects the electron tunneling barrier from collapsing, even in the limit of repulsive forces. However, we find subtle conductance and force variations at different contacting sites along the C_{2}H_{2} molecule attributed to a weak overlap of their respective frontier orbitals.