title: Effect of Perylene Photosensitizer Attachment to [Pd(triphosphine)L]2+on CO2Electrocatalysis.
abstract: Two new covalently linked chromophore-CO2reduction catalyst systems were prepared using a perylene chromophore and a bis[(dicyclohexylphosphino)ethyl]phenylphosphinopalladium(II) catalyst. The primary goal of this study is to probe the influence of photosensitizer attachment on the electrocatalytic performance. The position either para or meta to the phosphorus on the phenyl group of the palladium complex was linked via a 2,5-xylyl group to the 3 position of perylene. The electrocatalytic CO2reduction activity of the palladium complex is maintained in the meta-linked system, but is lost in the para-linked system, possibly because of unfavorable interactions of the perylene chromophore with the glassy carbon electrode used. Following selective photoexcitation of the perylene, an enhanced perylene excited-state decay rate was observed in the palladium complexes compared to perylene attached to the free ligands. This decrease is accompanied by formation of the perylene cation radical, showing that electron transfer from perylene to the palladium catalyst occurs. Electron transfer and charge recombination were both found to be faster in the para-linked system than in the meta-linked one, which is attributed to stronger electronic coupling in the former. These results illustrate the need to carefully tune the electronic coupling between a photosensitizer chromophore and the catalyst to promote photodriven electron transfer yet inhibit adverse electronic effects of the chromophore on electrocatalysis.
authors.affiliation: Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208-3113, United States.
authors.forename: Rita E
authors.initials: RE
authors.lastname: Cook
authors.affiliation: Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208-3113, United States.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Phelan
authors.affiliation: Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208-3113, United States.
authors.forename: Leah E
authors.initials: LE
authors.lastname: Shoer
authors.affiliation: Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208-3113, United States.
authors.forename: Marek B
authors.initials: MB
authors.lastname: Majewski
authors.affiliation: Department of Chemistry and Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208-3113, United States.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wasielewski