title: Ultrafast Photoinduced Symmetry-Breaking Charge Separation and Electron Sharing in Perylenediimide Molecular Triangles.
abstract: We report on a visible-light-absorbing chiral molecular triangle composed of three covalently linked 1,6,7,12-tetra(phenoxy)perylene-3,4:9,10-bis(dicarboximide) (PDI) units. The rigid triangular architecture reduces the electronic coupling between the PDIs, so ultrafast symmetry-breaking charge separation is kinetically favored over intramolecular excimer formation, as revealed by femtosecond transient absorption spectroscopy. Photoexcitation of the PDI triangle dissolved in CH2Cl2 gives PDI(+•)-PDI(-•) in τCS = 12.0 ± 0.2 ps. Fast subsequent intramolecular electron/hole hopping can equilibrate the six possible energetically degenerate ion-pair states, as suggested by electron paramagnetic resonance/electron-nuclear double resonance spectroscopy, which shows that one-electron reduction of the PDI triangle results in complete electron sharing among the three PDIs. Charge recombination of PDI(+•)-PDI(-•) to the ground state occurs in τCR = 1.12 ± 0.01 ns with no evidence of triplet excited state formation.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Wu
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Young
authors.forename: Marco
authors.initials: M
authors.lastname: Frasconi
authors.forename: Severin T
authors.initials: ST
authors.lastname: Schneebeli
authors.affiliation: Institut für Organische Chemie and Center for Nanosystems Chemistry, Universität Würzburg , Am Hubland, 97074 Würzburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Spenst
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Gardner
authors.forename: Kristen E
authors.initials: KE
authors.lastname: Brown
authors.affiliation: Institut für Organische Chemie and Center for Nanosystems Chemistry, Universität Würzburg , Am Hubland, 97074 Würzburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Würthner
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Stoddart
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wasielewski
mesh_terms: D004583:Electrons; D007094:Imides / Q000737:chemistry*; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry; D055668:Photochemical Processes; D066244:Proton Magnetic Resonance Spectroscopy; D013050:Spectrometry, Fluorescence; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007094:Imides; C521332:perylenediimide; D010569:Perylene