title: High turnover in a photocatalytic system for water reduction to produce hydrogen using a Ru,  Rh,  Ru photoinitiated electron collector.
abstract: Covalent coupling of Ru(II) light absorbers to a Rh(III) electron collecting site through polyazine bridging ligands affords photocatalytic production of H(2) in the presence of visible light and a sacrificial electron donor. A robust photocatalytic system displaying a high turnover of the photocatalyst has been developed using the photoinitiated electron collector [{(bpy)(2)Ru(dpp)}(2)RhBr(2)](5+) (bpy=2,2'-bipyridine; dpp=2,3-bis(2-pyridyl)pyrazine) and N,N-dimethylaniline in DMF/H(2)O. Studies have shown that increased [DMA], the headspace volume, and the use of DMF solvent improves the systems performance and stability providing mechanistic insight into the deactivation routes of the photocatalytic system. Photolysis of the system at 460 nm generates 20 mL of H(2) in 19.5 h with a maximum Φ=0.023 based on H(2) produced and an overall Φ=0.014 and 280 turnovers of the photocatalyst. The photocatalytic system also displays long-term photostability with 30 mL of H(2) generated and 420 turnovers in 50 h under the same conditions. Prolonged photolysis provides 820 mol H(2) per mole of catalyst.
authors: Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060-0212, USA.
authors: Shamindri M
authors: SM
authors: Arachchige
authors: Ryan
authors: R
authors: Shaw
authors: Travis A
authors: TA
authors: White
authors: Vimal
authors: V
authors: Shenoy
authors: Hei-Man
authors: HM
authors: Tsui
authors: Karen J
authors: KJ
authors: Brewer
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D002384:Catalysis; D004583:Electrons; D006859:Hydrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D012238:Rhodium / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D009942:Organometallic Compounds; D012997:Solvents; D014867:Water; D012428:Ruthenium; D006859:Hydrogen; D012238:Rhodium; C023650:aniline