Unprecedented regioselective post-functionalization of racemic and enantiopure cationic diaza helicenes is afforded. The peripheral auxochrome substituents allow a general tuning of the electrochemical, photophysical and chiroptical properties of the helical dyes (26 examples). For instance, electronic absorption and circular dichroism are modulated from the orange to near-infrared spectral range (575–750 nm), fluorescence quantum efficiency is enhanced up to 0.55 (631 nm) and circularly polarized luminescence is recorded in the red (|glum| ∼ 10−3).
I. Hernández Delgado, S. Pascal, A. Wallabregue, R. Duwald, C. Besnard, L. Guénée, C. Nançoz, E. Vauthey, R. Tovar, J. Lunkley, Gilles Muller, and J. Lacour. "Functionalized cationic helicenes with unique tuning of absorption, fluorescence and chiroptical properties up to the far-red range" Chemical Science (2016): 4685-4693. doi:10.1039/C6SC00614K