Locally Rotated Chiral Molecular Tiara with Reversible CPL Emissions

Abstract Chiroptical materials capable of emitting circularly polarized luminescence (CPL) have been gaining intensive interest for their wide applications in fields of materials. In this work, a locally rotated molecular tiara Py 5 P5 , in which five bulky pyrene units locate at one rim of Py 5 P5 , and five small methoxy groups at the other, is designed. The planar chiral skeleton of Py 5 P5 can make five pyrene units being ordered in asymmetrical manner to arise the CPL emission from pyrene excimer, and the small methoxy groups rim in the other can ensure the interconversion between p R‐ and p S‐conformers of Py 5 P5 freely via local rotation. Thus, both left‐handed and right‐handed CPL may emit from pyrene units of Py 5 P5 stacked in the asymmetrical order with a high | g lum | up to 1.28 × 10 −3 under the induction of chiral amino acid derivatives. It is the first observation that both right‐handed and left‐handed CPL from pyrene excimer can be arisen from a single molecule by adding the simple chiral guests.