Small Figure‐Eight Luminophores: Double‐Twisted Tethered Cyclic Binaphthyls Boost Circularly Polarized Luminescence
Yuki Nojima, Masashi Hasegawa, Nobuyuki Hara, Yoshitane Imai, Yasuhiro Mazaki
Abstract
Abstract Double‐twisted cyclic binaphthyls, in which two naphthalenes are tethered by ‐O(CH 2 ) n O‐ linkage ( n =1–3), have been synthesized. X‐ray analyses and DFT calculations revealed a tightly constrained stereogenic figure‐eight geometry. Tethering of two naphthalenes by short linkage forces a small dihedral angle, and the cyclic binaphthyls with short tether ( n =1, 2) exhibit remarkable boosting of the g lum value (1.0–1.6×10 −2 ) in circularly polarized luminescence (CPL) and unusual g lum / g abs ratios (0.93–1.3). These experimental high | g lum | values are in accord with the results of excited state TD‐DFT calculations, which show transannular interactions and that consequent extensive delocalization occurs throughout the figure‐eight π‐core. As a result, the present figure‐eight luminophore promote the elongation of the magnetic transition dipole moment that results in significant increases in g lum values.