Polyazine-Bridged Ru(II),Pt(II) Trimetallic and Tetrametallic Supramolecular Complexes Exhibiting Unusual Excited State Dynamics Important in Catalysis and PDT Drug Development

Content Provider	Semantic Scholar
Author	Knoll, Jessica D.
Copyright Year	2013
Abstract	The goal of this research was to develop structurally diverse polyazine-bridged Ru(II),Pt(II) trimetallic and tetrametallic supramolecular complexes and study the impact of component variation on the redox, spectroscopic, and excited state properties that influence photoinduced charged separation and multielectron reduction. These complexes are active photocatalysts for H2O reduction to H2. Tetrametallic complexes with the supramolecular architecture [{(TL)2Ru(dpp)}2Ru(BLʹ)PtCl2] (Ru3Pt; TL = phen = 1,10-phenanthroline or Ph2phen = 4,7-diphenyl-1,10-phenanthroline; BLʹ = dpp = 2,3-bis(2pyridyl)pyrazine or dpq = 2,3-bis(2-pyridyl)quinoxaline) feature a trimetallic dpp-bridged Ru(II) light absorber coupled to a cis-PtCl2 reactive metal center. Trimetallic complexes with one less Ru-based light absorbing unit, [{(Ph2phen)2Ru(dpp)Ru(bpy)(BLʹ)PtCl2] (Ru2Pt; BLʹ = dpp or dpq), represent a new supramolecular architecture that was designed and synthesized to provide less complex systems for excited state analysis. Both the Ru3Pt and Ru2Pt systems have a remote Ru center separated from the reactive Pt site designed to provide extended MLCT lifetimes relative to directly coupled [(TL)2Ru(BL)PtCl2] systems. The building block synthetic method used in constructing supramolecules provides the ability to purify and analyze the properties following each synthetic step, allowing sub-unit variation and structural diversity. Building a knowledge base about the properties of smaller, less complicated structures is critical in understanding the electrochemistry, spectroscopy, and excited state dynamics of multi-metallic, multi-ligand complexes. Electrochemical analysis of the [{(TL)2Ru(dpp)}2Ru(BLʹ)PtCl2] complexes suggests a HOMO localized on the terminal Ru centers (E1/2 (Ru) = 1.56-1.63 V vs. Ag/AgCl) and a LUMO localized on the remote BLʹ coordinated to the reactive Pt site, with the energy dictated by the BLʹ identity (E1/2 = −0.32 or −0.33 V for BLʹ = dpp or E1/2 = −0.02 or −0.05 V for BLʹ = dpq). This provides
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Language	English
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