title: Reaction of Ru(II) diazafluorenone compound with nanocrystalline TiO2 thin film.
abstract: The Ru(II) compounds [Ru(bpy)(2)(mcbH)](2+) and [Ru(bpy)(2)(dafo)](2+), bpy is 2,2'-bipyridine where mcbH is 3-(CO(2)H)-2,2'-bipyridine and dafo is 4,5-diazafluoren-9-one, were synthesized, characterized, and anchored to nanocrystalline mesoporous TiO(2) thin films for excited state and interfacial electron transfer studies. X-ray crystallographic studies of [Ru(bpy)(2)(mcbH)](PF(6))(Cl) revealed a long Ru-N distance to the unsubstituted pyridine ligand of mcbH. Reaction of [Ru(bpy)(2)(dafo)](2+) with TiO(2) thin films resulted in interfacial chemistry. The IR, (1)H NMR, UV-vis, and photoluminescence spectral data indicated a room-temperature ring-opening reaction of the dafo ligand of [Ru(bpy)(2)(dafo)](2+) that ultimately yielded a carboxylate group in the 3-position of bipyridine anchored to TiO(2). Comparative reactions of [Ru(bpy)(2)(mcbH)](2+) with TiO(2) were performed and support this conclusion. In regenerative photoelectrochemical solar cells with 0.5 M LiI/0.05 M I(2) in acetonitrile, photocurrent action spectra were observed for both sensitized materials. The incident photon-to-current efficiency (IPCE) was significantly lower for Ru(bpy)(2)(dafo)/TiO(2), behavior attributed to a lower excited-state injection yield.
authors.affiliation: Chemistry Department, United States Naval Academy, Annapolis, Maryland 21402, USA. heuer@usna.edu
authors.forename: William B
authors.initials: WB
authors.lastname: Heuer
authors.forename: Hai-Long
authors.initials: HL
authors.lastname: Xia
authors.forename: Maria
authors.initials: M
authors.lastname: Abrahamsson
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhou
authors.forename: Shane
authors.initials: S
authors.lastname: Ardo
authors.forename: Amy A
authors.initials: AA
authors.lastname: Narducci Sarjeant
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Meyer