title: Charge-transfer emission of compact porphyrin-fullerene dyad analyzed by Marcus theory of electron-transfer.
abstract: A porphyrin-fullerene dyad, which is characterized by a close proximity of the porphyrin donor and the fullerene acceptor, was found to undergo a photoinduced electron transfer both in solutions and in solid films. Near-infrared charge-transfer (CT) emission was observed and analyzed in frame of the semi-classical Marcus electron-transfer theory yielding values for the reaction free energy, -deltaG degrees = 1.75 eV, the internal reorganization energy, lambdav = 0.05 eV, and the donor-acceptor vibrational energy, hv(v) = 0.14 eV, both in solution and in solid film. The influence of the environment on the CT properties of the dyad is described by a single parameter, the outer-sphere reorganization energy, lambdas, which varies from 0.05 eV in non-polar solvents and films to 0.13 eV in solvents of moderate polarity. At low temperatures (T< 200 K), the CT emission consists of distinct bands shifted from each other by value hv(v). This is the first direct observation of the vibrational frequencies of a porphyrin-fullerene donor-acceptor system.
authors.affiliation: Institute of Materials Chemistry, Tampere University of Technology, Finland. visa.vehmanen@tut.fi
authors.forename: V
authors.initials: V
authors.lastname: Vehmanen
authors.forename: N V
authors.initials: NV
authors.lastname: Tkachenko
authors.forename: H
authors.initials: H
authors.lastname: Imahori
authors.forename: S
authors.initials: S
authors.lastname: Fukuzumi
authors.forename: H
authors.initials: H
authors.lastname: Lemmetyinen
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D002244:Carbon / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D037741:Fullerenes; D008956:Models, Chemical; D017319:Photosensitizing Agents / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry / Q000379:methods*; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D037741:Fullerenes; D017319:Photosensitizing Agents; D011166:Porphyrins; D002244:Carbon; C069837:fullerene C60