Optically Active A-Shaped Cyclic Molecules Based on Planar Chiral [2.2]Paracyclophanes Emitting Bright Circularly Polarized Luminescence with High Anisotropy Factors

Optically active A-shaped cyclic molecules are synthesized by incorporating a planar chiral [2.2]paracyclophane unit to form a helical structure. These molecules exhibit large molar absorption coefficients, moderate photoluminescence (PL) quantum efficiencies, and high circularly polarized luminescence (CPL) anisotropy factors, resulting in high CPL brightness values (BCPL values). According to the time-dependent density functional theory (TD-DFT) theoretical studies, extended pi-conjugated moieties act as light-harvesting units, and emissions occur from the helical skeletons. The TD-DFT calculations reproduce the experimentally determined absorption, PL, circular dichroism, and CPL properties of the A-shaped cyclic molecules. Two kinds of optically active A-shaped molecules are synthesized from enantiopure planar chiral [2.2]paracyclophanes to form one-handed helical higher-ordered structures. The molecules exhibit large molar absorption coefficients, moderate photoluminescence quantum efficiencies, and high circularly polarized luminescence anisotropy factors (|glum| values) of the order of 10-2, resulting in high CPL brightness values (BCPL values) over 350 M-1cm-1.image

Automated summary

Optically active A-shaped cyclic molecules with helical structures were synthesized by incorporating a planar chiral [2.2]paracyclophane unit. These molecules exhibited excellent optical properties and the experimental results agreed well with theoretical calculations.