Chiral Amplification in π‑Conjugated Helical Polymers with Circularly Polarized Luminescence

Abstract

A series of d-glucose-bound optically active π-conjugated polymers (poly-Tr) were synthesized by ternary copolymerization of 2,5-diiodothiophene with diethynyl monomers containing a chiral and an achiral biphenyl unit using the Sonogashira coupling reaction. The effect of the chiral and achiral biphenyl contents on the chiral amplification in the preferred-handed helix formation (“the sergeants and soldiers effect”) was investigated by comparing the circular dichroism (CD) and circularly polarized luminescence (CPL) intensities of poly-Tr to that of the corresponding helical polymer (poly-T) without an achiral biphenyl unit. We observed that even when the chiral biphenyl content in the copolymer was 50 mol % (poly-T0.50), its CD and CPL intensities were almost comparable to that of poly-T, demonstrating the amplification of the helicity