Guiding the formation of single-handed enantiomeric porphyrin domains using kinked and chiral stepped surfaces

The self-assembly of nickel tetraphenyl porphyrin (NiTPP) on achiral Au(111), which includes randomly located kinked steps, and chiral Au(1036 1070 1035) and (1036 1035 1070) surfaces has been studied using UHV scanning tunneling microscopy. The clean surfaces of the achiral and chiral gold crystals were characterized with STM. Subsequently, NiTPP molecules were deposited on each surface. On achiral Au(111), the porphyrins assemble into racemic mixtures of enantiomerically resolved domains. It is concluded that, on large flat terraces, intermolecular interactions are the dominant factor in the chiral assembly. Moreover, it is found that the chirality of the molecular array can be guided using the handedness of locally kinked step edges. Preliminary work has begun on the chiral crystal surfaces. Initial findings suggest that the chirality of the kinked step edges induces formation of a single-handed domain of molecules across a terrace.