Combined reversible switching of ECD and quenching of CPL with chiral fluorescent macrocycles

Straightforward synthesis and resolution of a series of chiral fluorescent macrocycles are presented, together with their electronic circular dichroism (ECD), strong excimer fluorescence (EF, λ 300 to 650 nm) and allied highly circularly polarized luminescence (CPL, g(lum) up to 1.7 × 10(–2)). The ECD, EF and CPL responses are strongly affected by the presence of metal ions (Na(+), Ba(2+)) thanks to deep conformational changes. While ECD signals can be almost completely reversibly inverted upon the complexation/decomplexation of metal ions in a typical binary response, CPL signals are reversibly quenched concomitantly. The designed macrocycles display thus a remarkable combination of both +/– ECD and on/off CPL reversible switching.