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Physicochemical and Electronic Properties of Cationic [6]Helicenes: from Chemical and Electrochemical Stabilities to Far-Red (Polarized) Luminescence
Chemistry - A European Journal (2016)
  • Dr. Johann Bosson, University of Geneva
  • Geraldine M. Labrador, University of Geneva
  • Dr. Simon Pascal, University of Geneva
  • Dr. François-Alexandre Miannay, University of Geneva
  • Oleksandr Yushchenko, University of Geneva
  • Haidong Lu, University of Bordeaux and CNRS
  • Dr. Laurent Bouffier, University of Bordeaux and CNRS
  • Prof. Neso Sojic, University of Bordeaux and CNRS
  • Roberto C. Tovar, San Jose State University
  • Gilles Muller, San Jose State University
  • Prof. Denis Jacquemin, Université de Nantes
  • Dr. Adèle D. Laurent, Université de Nantes
  • Dr. Boris Le Guennic, Université de Rennes
  • Prof. Eric Vauthey, University of Geneva
  • Prof. Jérôme Lacour, University of Geneva
The physicochemical properties of cationic dioxa (1), azaoxa (2), and diaza (3) [6]helicenes demonstrate a much higher chemical stability of the diaza adduct 3 (pKR+=20.4,  =−0.72 V) compared to its azaoxa 2 (pKR+=15.2,  =−0.45 V) and dioxa 1 (pKR+=8.8,  =−0.12 V) analogues. The fluorescence of these cationic chromophores is established, and ranges from the orange to the far-red regions. From 1 to 3, a bathochromic shift of the lowest energy transitions (up to 614 nm in acetonitrile) and an enhancement of the fluorescence quantum yields and lifetimes (up to 31 % and 9.8 ns, respectively, at 658 nm) are observed. The triplet quantum yields and circularly polarized luminescence are also reported. Finally, fine tuning of the optical properties of the diaza [6]helicene core is achieved through selective and orthogonal post-functionalization reactions (12 examples, compounds 415). The electronic absorption is modulated from the orange to the far-red spectral range (560–731 nm), and fluorescence is observed from 591 to 755 nm with enhanced quantum efficiency up to 70 % (619 nm). The influence of the peripheral auxochrome substituents is rationalized by first-principles calculations.
Publication Date
Citation Information
Johann Bosson, Geraldine M. Labrador, Simon Pascal, François-Alexandre Miannay, et al.. "Physicochemical and Electronic Properties of Cationic [6]Helicenes: from Chemical and Electrochemical Stabilities to Far-Red (Polarized) Luminescence" Chemistry - A European Journal Vol. 22 Iss. 51 (2016) p. 18394 - 18403
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