Binaphthyl‐Bridged Pyrenophanes: Intense Circularly Polarized Luminescence Based on a<i>D</i><sub>2</sub>Symmetry Strategy
Kazuto Takaishi, Sho Murakami, Fumiya Yoshinami, Tadashi Ema
Abstract
Abstract A series of D 2 ‐symmetric macrocycles composed of alternately linked pyrene and binaphthyl moieties (binaphthyl‐bridged pyrenophanes) have been synthesized. Among them, a pyrenophane possessing ether linkers at the 2,7‐positions of the pyrenes exhibited intense circularly polarized luminescence (CPL) with a | g lum | value of 0.053. This value is by far the highest for excimers and was not sensitive to temperature, solvent, or concentration. The CPL originated from a twisting pyrene excimer, with the ( R )‐binaphthyl moieties producing a left‐handed twist excimer, which exhibited (−)‐CPL. The electric and magnetic transition dipole moments are perfectly parallel, which is the best relationship for strong CPL.