Enantioenriched Ruthenium-Tris-Bipyridine Complexes Bearing One Helical Bipyridine Ligand: Access to Fused Multihelicenic Systems and Chiroptical Redox Switches

The synthesis and photophysical chiroptical properties of novel aza[n]helicenes (6a–d, 10a,b, n = 4–7) substituted with one or two 2-pyridyl groups are described. preparation was performed via an adapted Mallory reaction using aromatic imines as precursors. obtained class helical 2,2?-bipyridine ligands then coordinated to Ru(bipy)22+ units, thus affording the first diastereomerically enantiomerically pure [RuL(bipy)2]2+ (11a,c, L 6a,c) [Ru2L?(bipy)4]4+ (12, L? 10b) complexes. topology stereochemistry these metal-based architectures were studied in detail, notably X-ray crystallography. Interestingly, coordination ruthenium(II) enabled fused multihelical systems incorporating aza- ruthena-helicenes within same scaffold. photophysical, chiroptical, redox complexes examined efficient redox-triggered switching activity evidenced.