Cryptochiral binaphthyl–bipyrene luminophores linked with alkylene esters: intense circularly polarised luminescence, but ultraweak circular dichroism

A C-2-symmetric binaphthyl-based luminophore connected to two luminescent pyrene pendants was designed to express cryptochirality, as demonstrated by the ultraweak circular dichroism signals observed in their ground state. The observed results were due to the unrestricted rotational freedom of the flexible ester wires between the binaphthyl and pyrene moieties in the absence of light. Finally, the C-2-symmetric luminophore revealed photoexcited chirality, as confirmed by intense circularly polarised luminescence.