Tunable circularly polarized luminescence of D–A type chiral conjugated oligomers via achiral donors

Abstract

Chiral conjugated oligomers with circularly polarized luminescence (CPL) have received great interest and been extensively researched. However, chiral conjugated oligomers with donor–acceptor (D–A) structures are poorly developed. In this paper, a series of D–A-type chiral conjugated oligomers were synthesized by the copolymerization of axially chiral acceptors and achiral donors through Pd-catalyzed Buchwald–Hartwig C–N coupling reactions. The resulting chiral conjugated oligomers exhibit donor-dependent fluorescence in solution with emission wavelengths ranging from 500 to 574 nm and photoluminescence quantum yields (Φ_PL) of up to 49%, which can be attributed to the ICT transition derived from the D–A oligomer backbone. Obvious CPL response signals can be detected for the chiral conjugated oligomers with luminescence dissymmetry factors (g_lum) of up to 1.3 × 10⁻³, which can be tuned via the variation of achiral donors. This work can provide a novel strategy for the design of chiral conjugated polymers or oligomers with D–A structures and tunable CPL signals.