  On-surface metal-organic coordination provides a promising way for
synthesizing different two-dimensional lattice structures that have been
predicted to possess exotic electronic properties. Using scanning tunneling
microscopy (STM) and spectroscopy (STS), we studied the supramolecular
self-assembly of 9,10-dicyanoanthracene (DCA) molecules on the Au(111) surface.
Close-packed islands of DCA molecules and Au-DCA metal-organic coordination
structures coexist on the Au(111) surface. Ordered DCA$_{3}$Au$_{2}$
metal-organic networks have a structure combining a honeycomb lattice of Au
atoms with a kagome lattice of DCA molecules. Low-temperature STS experiments
demonstrate the presence of a delocalized electronic state containing
contributions from both the gold atom states and the lowest unoccupied
molecular orbital of the DCA molecules. These findings are important for the
future search of topological phases in metal-organic networks combining
honeycomb and kagome lattices with strong spin-orbit coupling in heavy metal
atoms.
