Design of nanoscale molecular wire based on diphenylacetylene: Role of linkage

Theoretical investigation has been performed on electron transport properties of diphenylacetylene-based molecules sandwiched between two gold surfaces. Different linkers such as sulfur, nitrogen, oxygen, CS, CO, CN, NS, NO and NN have been considered to study the role of linkage in the conduction properties of the molecular wire. The charge transfer across the metal–molecule and bonding nature at the interfacial contact are illustrated by natural bond orbital analysis. It is found that Au can covalently bond to diphenylacetylene through nitrogen or sulfur linkages while its weak interaction through oxygen linkage has non-covalent character in nature. The dependence of the molecular electronic structure of the gold–molecule complexes on the external electric field has been also studied. The electronic conduction has been analyzed from the change in the shape of molecular orbitals and the evolution of the HOMO–LUMO gap of the molecule-gold complexes under the influence of the electric filed.