Synthesis and Chiroptical Properties of Radially Extended Carbazole with Chiral 2.2Paracyclophane Core

Abstract 2.2Paracyclophanes (2.2PCs) with substituents at specific positions possesses planar chirality and stands as a promising building unit for the development of chiroptical materials associated with polarized light. However, one of the easily accessible starting materials, bromo‐substituted 2.2PC, shows low reactivity, and effective methods for π‐extension of planar chiral 2.2PC are limited. Herein, an effective π‐extension method has established for chiral 2.2PC with four substitutions from 4,7,12,15‐tetrabromo2.2PC. This has led to tetrakis(trimethylsilylphenyl)‐2.2PC that serves as a versatile building resource for radial‐type chiral π‐conjugated compounds with a 2.2PC core. In this study, synthesizing compounds are further succeeded with the introduction of carbazole ( Cbz 4 ‐2.2PC and t BuCbz 4 ‐2.2PC ) and investigated their chiroptical properties and chiral induction ability in achiral π‐conjugated polymers. A thin film of Poly[9,9‐dioctylfluorenyl‐2,7‐diyl)‐alt‐(benzo[2,1,3thiadiazol‐4,7‐diyl)]] (F8BT) with 3wt% Cbz 4 ‐2.2PC prepared by spin‐coating exhibits circularly polarized luminescence (CPL) properties with a high dissymmetry factor (| g lum | = 0.01), which is much higher than that of Cbz 4 ‐2.2PC in CH 2 Cl 2 solution. By contrast, the doped film of F8BT with 3wt% t BuCbz 4 ‐2.2PC exhibited only weak CPL properties. In addition, these chiral compounds show facile redox properties owing to the presence of carbazole units. Furthermore, Cbz 4 ‐2.2PC undergoes electropolymerization to produce an insoluble thin film on the electrode.