Vanol-Supported Lanthanide Complexes for Strong Circularly Polarized Luminescence at 1550 nm

Strong circularly polarized luminescence (CPL) at 1550 nm is reported for lanthanide complexes supported by Vanol; these are the first examples of coordination of Vanol to lanthanides. A change in the ligand design from a 1,1'-bi-2-naphthol (in Binol) to a 2,2'-bi-1-naphthol (in Vanol) results in significantly improved dissymmetry factors for (Vanol)₃ ErNa₃ (|g_lum |=0.64) at 1550 nm. This is among the highest reported dissymmetry factors to date in the telecom C-band region, and among the highest for any lanthanide complexes. Comparative solid-state structural analysis of (Vanol)₃ ErNa₃ and (Binol)₃ ErNa₃ suggests that a less distorted geometry around the metal center is in part responsible for the high chiroptical metrics of (Vanol)₃ ErNa₃ . This phenomenon was further evidenced in the analogous ytterbium complex (Vanol)₃ YbNa₃ that also exhibit a significantly improved dissymmetry factor (|g_lum |=0.21). This confirms and generalizes the same observation that was made in other visibly emitting, six-coordinate lanthanide complexes. Due to their strong CPL at 1550 nm, the reported complexes are potential candidates for applications in quantum communication technologies. More importantly, our structure-CPL activity relationship study provides guidance towards the generation of even better near-infrared CPL emitters.