Chiral luminescent ion pair (CLIP) strategy enables amorphous platinum complexes circularly polarized phosphorescence

Abstract

Chiral ion-pairing (CIP) has been developed as an effective chirality transfer strategy from chiral ionic species to its achiral counter-ionic substrate. When the achiral counter-ions were endowed with luminescent properties, the resultant chiral luminescent ion pair (CLIP) will open a new window for high-performance chiral luminescence. In this research, three pairs of CLIP molecules featuring the platinum complexes as achiral cationic luminophores and the chiral anion (CA) as chiral source were constructed. The CLIP molecules demonstrate circularly polarized phosphorescence (CPP) with quantum yields (ΦPL) up to 71.5%, dissymmetry factor (gcpp) values of 1.8 × 10−2 in amorphous state and gcpp up to −0.99 in cholesteric liquid crystal (CLC). Results show that the chiroptical properties can be assigned to the chirality transfer from the CAs to the formed twisted dimeric or oligomeric self-assemblies of platinum complex cations. This research presents a new approach for achieving high-performance chiral luminescence of amorphous chiral metal complexes, providing a concise model for revealing the chirality transfer in CLIP materials. Graphical abstract: [Figure not available: see fulltext.]