Versatile Approach to Formation of Light-Harvesting Complexes on Nanostructured Metal Oxide Surfaces via "On-Surface" Assembly

TitleVersatile Approach to Formation of Light-Harvesting Complexes on Nanostructured Metal Oxide Surfaces via "On-Surface" Assembly
Publication TypeJournal Article
Year of Publication2014
AuthorsPutans, BA, Bishop, LM, Hamers, RJ
JournalChemistry of Materials
Volume26
Pagination3651-3659
Date Published06/2014
ISBN Number0897-4756
Keywordsadsorption, CHEMI-LUMINESCENCE, DYNAMICS, efficiency, EXCITED-STATES, LIGAND-EXCHANGE, MONOLAYERS, RUTHENIUM COMPLEXES, SENSITIZED SOLAR-CELLS, TIO2 SURFACES
Abstract

A versatile, two-step "on-surface" assembly method is demonstrated to build heteroleptic light-harvesting complexes on nanostructured metal oxide surfaces. In this process, building-block ligands were first attached to SnO2 surfaces by grafting 2,2'-bipyridine molecules that were modified at the (4,4') positions with surface-reactive binding groups. The surface-bound bipyridine ligands then served as a basis for "on-surface" assembly of complete surface-bound Ru(bpy)(3) complexes by immersing the bipyridyl-modified samples in a solution containing the complex [Ru(bpy)(2)(CH3CN)(2)](PF6)(2) and illuminating with ultraviolet light, which removes the photolabile acetonitrile ligands and allows the solution-phase complex to react with the surface-bound bipyridine molecules to form complete surface-bound Ru(bpy)(3) complexes. We demonstrate that this process is effective using three different surface attachment schemes based on aryl-iodo, benzyl-iodo, and dithione bipyridine derivatives. The stability of the complexes in water and the charge transfer characteristics were then measured for the different ligand attachment methods. The benzyl-iodo complex provides the best surface coverage and greatest stability. We also demonstrated that the building-block ligand can act as a site for regeneration of the complexes on the surface.

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