Synthesis Amphiphilic One-Handed Helical Ladder Polymers with Circularly Polarized Luminescence

Helical ladder polymers attract attention because of their well-defined, one-handed helical ladder structures and unique properties, which differ from precursor polymers that have random-coil conformations. However, the synthesis of helical ladder polymers is difficult and inhibits their functions and applications. In this study, we reported the synthesis of amphiphilic optically active 2,2'-tethered binaphthyl-embedded helical ladder polymers carrying hydrophilic oligo (ethylene glycol) (OEG) as side chains through quantitative and chemoselective acid-promoted intramolecular cyclization of random-coil precursor polymers. The obtained helical ladder polymers exhibited dramatic circular dichroism (CD) and circularly polarized luminescence (CPL) enhancement. Moreover, we further established a circularly polarized fluorescence-energy transfer (CPF-ET) strategy in which the helical ladder polymers work as a donor, emitting circularly polarized fluorescence to excite an achiral fluorophore (coumarin-6) as the acceptor, producing green CPL with luminescence dissymmetry factor (2.5 × 10^-4).