Supramolecular Environment-Dependent Electronic Properties of Metal–Organic Interfaces.

Model donor–acceptor assemblies at metal–organic interfaces, namely, fluorinated copper-phthalocyanines (F16CuPC) and pentacene (PEN) assemblies on the Au(111) surface, have been the focus of the present study. A full picture of the crystallographic and electronic structure of PEN and F16CuPC monolayers as well as of their 1:1 binary mixture on the Au(111) surface has been explored by means of a variety of surface-sensitive techniques, providing important information on the intermolecular and molecule–substrate interactions governing the self-assembly process. A long-range ordered donor–acceptor network is observed for the mixture as a result of the greatly enhanced intermolecular interaction via C–F···H–C hydrogen bonds. Interestingly, the new supramolecular structure involves changes in the electronic structure of the molecular components. In particular, the strongest changes are observed at the C and F atoms of the F16CuPc, as opposed to the F16CuPc N, Cu, or PEN C atoms. With the aid of theoretical calculations, such effects are found to be at least partially related to an upward shift in energy of the F16CuPc molecular orbitals, concomitant with a molecule-to-metal charge donation, not from the HOMO, but deeper lying orbitals.