TY - JOUR AU - Bosson, Johann AU - Labrador, Geraldine M. AU - Pascal, Simon AU - Miannay, François-Alexandre AU - Yushchenko, Oleksandr AU - Li, Haidong AU - Bouffier, Laurent AU - Sojic, Neso AU - Tovar, Roberto C. AU - Muller, Gilles AU - Jacquemin, Denis AU - Laurent, Adèle D. AU - Le Guennic, Boris AU - Vauthey, Eric AU - Lacour, Jérôme TI - Physicochemical and Electronic Properties of Cationic [6]Helicenes: from Chemical and Electrochemical Stabilities to Far-Red (Polarized) Luminescence PY - 2016 JF - Chemistry - A European Journal JA - Chem. - Eur. J. SN - 0947-6539 VL - 22 IS - 51 SP - 18394 EP - 18403 L1 - http://onlinelibrary.wiley.com/doi/10.1002/chem.201603591/epdf L2 - http://onlinelibrary.wiley.com/enhanced/doi/10.1002/chem.201603591 L3 - http://doi.wiley.com/10.1002/chem.201603591 L4 - http://www.unige.ch/sciences/chifi/publis/pics/double/ref01533.png M3 - 10.1002/chem.201603591 UR - http://dx.doi.org/10.1002/chem.201603591 KW - circularly polarized luminescence KW - density functional calculations KW - electrochemistry KW - fluorescence KW - helicenes N2 - 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, Ered1/2 =−0.72 V) compared to its azaoxa 2 (pKR+=15.2, Ered1/2=−0.45 V) and dioxa 1 (pKR+=8.8, Ered1/2=−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 4–15). 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. ID - 1533 ER -