• A Donor–Acceptor Tetrathiafulvalene Ligand Complexed to Iron(II): Synthesis, Electrochemistry, and Spectroscopy of [Fe(phen)2(TTF-dppz)](PF6)2
    N. Dupont, Y.-F. Ran, S.-X. Liu, J. Grilj, E. Vauthey, S. Decurtins and A. Hauser
    Inorganic Chemistry, 52 (1) (2013), p306-312
    DOI:10.1021/ic3019277 | unige:25113 | Abstract | Article HTML | Article PDF
The synthesis and photophysical properties of the complex [Fe(phen)2(TTF-dppz)]2+ (TTF-dppz = 4′,5′-bis-(propylthio)tetrathiafulvenyl[i]dipyrido[3,2-a:2′,3′-c]phenazine, phen = 1,10-phenanthroline) are described. In this complex, excitation into the metal–ligand charge transfer bands results in the population of a high-spin state of iron(II), with a decay lifetime of approximately 1.5 ns, in dichloromethane, at room temperature. An intraligand charge transfer state can also be obtained and has a lifetime of 38 ps. A mechanism for the different states reached is proposed based on transient absorption spectroscopy.
The photophysical properties of the free neutral radical galvinoxyl were studied by a combination of femtosecond time-resolved spectroscopy and quantum chemical calculations. The electronic absorption spectrum is dominated by an intense band at 430 nm that is ascribed to the D9,10←D0 transitions. Upon photoexcitation at 400 nm, the population of the D9,10 states decays within less than 200 fs to the electronic ground state. This ultrafast internal conversion does not involve intramolecular modes with large amplitude motion as the measured dynamics does not show any significant dependence on the environment, but is most probably facilitated by a high density of electronic states of different character. Depending on the solvent, a weak transient band due to the galvinoxylate anion is also observed. This closed-shell species, which is fluorescent although its deactivation is also dominated by non-radiative decay, is generated upon biphotonic ionization of the solvent and electron capture. The ultrashort excited-state lifetime of the galvinoxyl radical precludes photoinduced disproportionation previously claimed to be at the origin of the formation of both anion and cation.
  • Effect of the Addition of a Fused Donor−Acceptor Ligand on a Ru(II) Complex: Synthesis, Characterization, and Photoinduced Electron Transfer Reactions of [Ru(TTF-dppz)2(Aqphen)]2+
    N. Dupont, Y.-F. Ran, H.-P. Jia, J. Grilj, J. Ding, S.-X. Liu, S. Decurtins and A. Hauser
    Inorganic Chemistry, 50 (8) (2011), p3295-3303
    DOI:10.1021/ic101951n | unige:15004 | Abstract | 2(Aqphen)]2+" target="_blank">Article HTML | Article PDF
The synthesis and the photophysical properties of the complex [Ru(TTF-dppz)2(Aqphen)]2+(TTF = tetrathiafulvalene, dppz = dipyrido-[3,2-a:2′,3′-c]phenazine, Aqphen = anthraquinone fused to phenanthroline via a pyrazine bridge) are described. In this molecular triad excitation into the metal−ligand charge transfer bands results in the creation of a long-lived charge separated state with TTF acting as electron donor and anthraquinone as terminal acceptor. The lifetime of the charge-separated state is 400 ns in dichloromethane at room temperature. A mechanism for the charge separation involving an intermediate charge-separated state is proposed based on transient absorption spectroscopy.
  • A Compactly Fused π-Conjugated Tetrathiafulvalene-Perylenediimide Donor-Acceptor Dyad
    M. Jaggi, C. Blum, N. Dupont, J. Grilj, S.-X. Liu, J. Hauser, A. Hauser and S. Decurtins
    Organic Letters, 11 (14) (2009), p3096-3099
    DOI:10.1021/ol901186n | unige:3553 | Abstract | Article HTML | Article PDF
The synthesis and structural characterization of a tetrathiafulvalene-fused perylenediimide molecular dyad is presented. Its largely extendedπ-conjugation provides intense optical absorption bands over a wide spectral range. The planar functional molecule exhibits a short-livednonluminescent excited state attributed to intramolecular charge separation.



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