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.