Surface-confined supramolecular coordination chemistry.

The non-covalent synthesis of coordination compounds and networks provides promising avenues towardsmetal-containing supermolecules and nanostructured materials with ultimate feature definition. An importantfactor for their further development, and their integration and exploitation in nanoscale functional systems,is the capability to prepare or organize them at well-defined substrates or templated environments. Supramolecularengineering on atomistically controlled surfaces has been propelled by the direct insight into low-dimensionalcoordination systems provided by scanning tunneling microscopy observations. Here we discuss the principlesof surface-confined supramolecular coordination chemistry, emphasizingself-assembly protocols conducted on surface atomic lattices employing metal centers to direct the organizationof molecular ligands and the template-induced organization of prefabricated metallosupramolecular species.The presented exemplary molecular-level studies elucidate the arrangement of organic adsorbates and transitionmetal adatoms on low-index metal and graphite surfaces. They reveal the interplay between molecule-adatom,intermolecular, and adsorbate-substrate interactions, which need to be balanced for the fabricationof low-dimensional nanostructures. The control and understanding of both the nature of metal-ligandinteractions and the resulting supramolecular organization on solid surfaces is decisive for the designof advanced architectures with concomitant functions. The realized metallosupramolecular compounds andarrays combine the properties of their constituent metal ions and organic ligands, and feature versatilestructural characteristics as well as attractive functional aspects: their redox, magnetic, spin-state,and electronic transitions.