Current–voltage curves for molecular junctions: pyrene vs diphenylacetylene

The I–V curves are computed for 2,7-dithiolpyrene and 4,4′-dithiol-diphenylacetylene between two Au(1 1 1) surfaces. For a given bias, up to about 2.5 eV, the current for 2,7-dithiolpyrene is about half that for 4,4′-dithiol-diphenylacetylene. However, the fused benzene rings in 2,7-dithiolpyrene eliminate the loss of current associated with rotation about the central C2 that can occur for 4,4′-dithiol-diphenylacetylene.