Tunable lanthanide-directed metallosupramolecular networks by exploiting coordinative flexibility through ligand stoichiometry.

We report the self-assembly of multi-component lanthanide coordination metallosupramolecular structures on a Au(111) surface. Eu atoms coordinate with two heterotypic ligands of quarterphenyl-4,4''-dicarbonitrile and 4',4''''-(1,4-phenylene)bis(2,2':6',2''-terpyridine). For carbonitrile ligand : terpyridyl stoichiometric ratios of 0.7, Eu atoms are primarily ligated in a four-fold coordination scheme. By increasing the carbonitrile ligand to reach a stoichiometry of 1.8, Eu atoms are ligated now in a five-fold coordination sphere. Two types of coordination schemes result in structures exhibiting one-dimensional and two-dimensional morphologies, respectively. This study demonstrates that the flexible lanthanide coordination sphere facilitates the rational design of metallosupramolecular architectures.