Metal-Organic Superlattices Induced by Long-Range Repulsive Interactions on a Metal Surface

Chains of dicyanovinyl-quinquethiophene (DCV5T-Me-2) molecules ionically bonded with Na atoms form a superlattice on Au(111). Through a detailed analysis of the interchain distances obtained from scanning tunneling microscopy images at various molecular coverages, we found that the chain arrangement substantially deviates from a random distribution of noninteracting chains. The distribution of chain spacings provides evidence for the existence of an interchain long-range repulsive potential. The experimental results can be modeled by a repulsive potential with a 1/d distance dependence, characteristic of Coulombic interactions. Density functional theory calculations of free-standing molecular chains reveal a charge depletion at the periphery of the chains, which is attributed to the intrinsic polar property of the molecule and is responsible for the long-range repulsion.

Automated summary

Experimental results show that DCV5T-Me-2 molecules form a superlattice on Au(111) surface, with the presence of long-range repulsive potential between chains leading to deviations from random distribution in chain arrangement.