Optically active triptycenes containing hexa-peri-hexabenzocoronene units

Abstract

A pair of novel optically active triptycene-based molecules ((R,R)-1 and (S,S)-1) containing two hexabenzocoronene moieties were synthesized and their optical and chiroptical properties were investigated. Optically active 1 emitted preferred-handed circularly polarized light upon UV irradiation, with the luminescence dissymmetry factors found to be approximately 1.0 × 10⁻³. Based on a comparative study using the analogous triptycene derivative with two hexaphenylbenzene units (2), which was the key precursor of 1, the ladder-type rigid structure with an asymmetrically bent geometry was important for optically active 1 to exhibit circularly polarized luminescence (CPL). We also showed that rac-1 undergoes conglomerate crystallization, which allowed CPL to be produced by a random selection of crystals prepared from rac-1.