Anchoring Hydroxamate Groups on Oxides: On-Surface Synthesis of a Jäger-Type Ligand and its Copper(II) Complexes

Herein, we report on the three-step synthesis of metal complexes on-surface of the powdered metal oxides alumina and titania . Planar-directing Jäger-type N 2 O 2 ligands were obtained from a diamine precursor which was anchored to the oxide surface with a hydroxamic acid moiety. IR and UV-Vis spectroscopies were used to prove the molecular integrity of the functional unit and to gain qualitative insights in the binding modes on the surface. It is demonstrated that the synthetic routines established for the synthesis of Jäger-type systems in homogeneous solution can be adapted to the solid state. That is, surface anchoring of a pre-ligand and successive stepwise synthetic transformations on-surface allow straightforward access to immobilized Jäger ligands and complexes. As a proof-of-principle, we studied the local environment of copper(II) ions in on-surface synthesized [Cu L ]@Al 2 O 3 by ESR spectroscopy. Well-resolved ESR spectra reveal intact N 2 O 2 coordination sites with ESR parameters that match molecular copper(II) reference complexes. On-surface metal-dilution series indicated that the competition between ligand-guided coordination and adsorption of free copper(II) can be tuned to be selective for [Cu L ]@Al 2 O 3 .