Surface isolation of single metal complexes or clusters by a coating sieving layer via atomic layer deposition

Surface immobilization of metal complexes or clusters with an exact metal number and coordination structure on solid supports is essential in many industrial applications. However, methods for physically isolating individual homogeneous catalyst molecules on a support surface are rare. By selectively depositing TiO2 sieving layers around supported Co(salen) single molecules or gold clusters with hydrophobic ligands, we realize molecular surface isolation via selective atomic layer deposition. The obtained catalysts are reusable in chiral hydrolytic kinetic resolution and styrene oxidation. Surface isolation also prevents the leaching and aggregation of gold clusters after removing the ligands at high temperature. The activity and selectivity for styrene oxidation to benzaldehyde over isolated single gold atoms are optimized with an enhanced Au-TiO2 interface. This method provides a simple way to immobilize homogeneous catalysts on inexpensive supports and shows excellent potential for industrialization.