Two-dimensional, phenanthroline-based, extended π-conjugated molecules for single-molecule conduction

Abstract

The conduction properties of phenanthroline-terminated, polycyclic extended π-conjugated molecular wires are investigated using density functional theory (DFT) in combination with Green's function techniques and group theory. While these molecules could possibly be thought of as accessible graphene-like fragments, they are calculated to conduct poorly. The decay constant for their exponential decrease of conductance with length is in excess of 0.6 Å−1 for the addition of internal fused quinoxaline groups and in excess of 0.9 Å−1 for the addition of internal pyrazine-fused pyrene groups. Furthermore, while the bidentate phenanthroline connectors adhere strongly to gold, they are sometimes predicted to be less conductive than related monodentate connectors. Careful design is thus required for any graphene-like extended π-system intended for single-molecule conduction applications.