6 research outputs found
Supramolecular and Intramolecular Energy Transfer with Ruthenium–Anthracene Donor–Acceptor Couples: Salt Bridge versus Covalent Bond
No full textThe formation of hydrogen-bonded cation-anion adducts between the complex [Ru(bpy)(2)(biimH(2))](2+) (bpy = 2,2'-bipyridine; biimH(2) = 2,2'-biimidazole)and anthracene-9-carboxylate in dichloromethane solution was investigated by H-1 NMR, optical absorption, and luminescence spectroscopy. The experimental data indicates that more than one anthracene-9-carboxylate anion can interact closely with the dicationic ruthenium complex. Energy transfer from the photoexcited ruthenium complex to anthracene-9-carboxylate in 1: 1 adducts of these two components was investigated by transient absorption spectroscopy and compared to intramolecular energy transfer in a covalently linked ruthenium-xyleneanthracene dyad with a comparable donor-acceptor distance.Swiss National Science Foundation [PP002-110611
Cyclometalated Iridium(III) Complexes as Photosensitizers for Long‐Range Electron Transfer: Occurrence of a Coulomb Barrier
No full textSix cyclometalated iridium(III) complexes were investigated to assess their potential as photosensitizers for long-range electron transfer, and two of them were incorporated directly into covalent donor-bridge-acceptor molecules. The influence of ligand substitutions on the excited-state properties and the photoredox behavior of the iridium complexes was explored by optical absorption, steady-state and time-resolved luminescence spectroscopy, as well as by electrochemical methods. Bimolecular electron transfer between the photoexcited complexes and 10-inethylphenothiazine and methylviologen was found to be only weakly dependent on the ligand substitutions. Intramolecular long-range electron transfer from phenothiazine to photoexcited iridium(III) in the dyads is slow due to the occurrence of a Coulomb barrier. Consequently, an electron-transfer photoproduct is only observable in the transient absorption spectrum of a donor-bridge-acceptor molecule with a fluorinated photosensitizer that exhibits a very long excited-state lifetime. A flash-quench technique is necessary for detection of an electron-transfer product in the dyad with a non-fluorinated photosensitizer. The occurrence of a Coulomb barrier associated with intramolecular (excited-state) long-range electron transfer in the dyads with cyclometalated iridium(III) photosensitizers represents an important difference to previously investigated similar donor-bridge-acceptor molecules with photosensitizers based on d(6) metal diimine complexes. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009
Supramolecular and Intramolecular Energy Transfer with Ruthenium–Anthracene Donor–Acceptor Couples: Salt Bridge versus Covalent Bond (Eur. J. Inorg. Chem. 35/2010)
No full textReading acts of narrative appropriation: four instances of fraudulent memoir
No full textPhDThis thesis examines acts of narrative appropriation, the telling of purportedly‘authentic’ life stories by those for whom the stories are not theirs to tell. This
misuse or subversion of genre - the discipline of historical writing and the category
of autobiography - becomes a means for cultural, social and political dissimulation,
and the analysis focuses both on the act: the event, trespass, or ‘theft’ of another’s
life story, and on the cultural meaning that this event reveals. These narrative acts
are approached theoretically through discussions of what it means to be an author, a
reader, and through the consideration of literary and social genre, category and form.
In exploring identities at particular risk of appropriation, this thesis shows how
fraudulent appropriated narratives affect our reading of the world, and in turn
influence our perception of already marginalized social groups. My primary
examples include prostitution ‘narratives’, Native North American ‘memoir,’ and
fraudulent Holocaust survivor ‘testimony,’ with each text providing decoded
evidence of ‘genre-bending’ exhibiting a social and political intent. These works
seek to be read as authentic personal narratives, as autobiography, and that is how
they have been presented to the reader. However, they are imposters – fictional tales
desiring the elevated status of historical authenticity and willing to bend the rules
and contracts of genre to achieve their end. Here the appearance of authenticity is
achieved through the use of cultural and social ‘myth,’ or perceptions of cultural
identity, and as such its fraudulent construction is first and foremost a social act,
with a social and economic motivation. As this thesis concludes, these texts are
most successful when their own political and social ideologies echo and confirm that
of the readership; when their subjects, the fraudulent ‘I’ at the center of the text is
also a performative elaboration of cultural belief
Chemistry with Photons, Protons, and Electrons
No full textThis is an account of the research activities of our group during the first two years of its existence. First results from our work on proton-coupled electron transfer and long-range charge tunneling reactions are presented. This includes a hydrogen-bonded cation–anion pair in
which a proton-coupled electron transfer process can be phototriggered and followed by simple optical spectroscopic means, as well as a series of rigid rod-like donor-bridge-acceptor molecules which we use to investigate physical phenomena associated with the tunneling of electrons or holes.
A unifying feature of this research is the use of light (photons) to induce proton and/or electron transfer
Ru-based donor-acceptor photosensitizer that retards charge recombination in a p-type dye-sensitized solar cell
No full textWe report on the synthesis and characterization of a donor-acceptor ruthenium polypyridyl complex as a photosensitizer for p-type dye-sensitized solar cells (DSSCs). The electrochemical, photophysical, and photovoltaic performance of two ruthenium-based photosensitizers were tested in NiO-based DSSCs; bis-(2,2'-bipyridine-4,4'-dicarboxylic acid)(2)N-(1,10-phenanthroline)-4-nitronaphthalene-1,8-dicarboximide ruthenium(ii), ([Ru(dcb)(2)(NMI-phen)](PF(6))(2)) and tris-(2,2'-bipyridine-4,4'-dicarboxylic acid)(3) ruthenium(ii), [(Ru(dcb)(3))Cl(2)]. The presence of an electron-accepting group, 4-nitronaphthalene-1,8-dicarboximide (NMI), attached to the phenanthroline of [Ru(dcb)(2)(NMI-phen)](2+) resulted in long-lived charge separation between reduced [Ru(dcb)(2)(NMI-phen)](2+) and NiO valence band holes; 10-50 μs. In the reduced state for [Ru(dcb)(2)(NMI-phen)](2+), the electron localized on the distal NMI group. In tests with I(3)(-)/I(-) and Co(4,4'-di-tert-butyl-bipyridine)(3)(2+/3+) electrolytes, [Ru(dcb)(2)(NMI-phen)](2+) outperformed [Ru(dcb)(3)](2+) in solar cell efficiency in devices. A record APCE (25%) was achieved for a ruthenium photosensitizer in a p-type DSSC. Insights on photosensitizer regeneration kinetics are included.</p
