Bis-4-aza[6]helicene: A Bis-helicenic 2,2′-Bipyridine with Chemically Triggered Chiroptical Switching Activity

A novel
enantiopure bis-helicenic 2,2′-bipyridine system
was prepared using a Negishi coupling. Thanks to the bipyridine unit,
the coordination with ZnII and protonation processes were
studied, revealing efficient tuning of photophysical (UV/visible and
emission) and chiroptical properties (electronic circular dichroism
and circularly polarized emission) of the system. The coordination/decoordination
and protonation/deprotonation processes appeared reversible, thus
constituting novel chiroptical switches.