Helical Polymer Working as a Chirality Amplifier to Generate and Modulate Multicolor Circularly Polarized Luminescence in Small Molecular Fluorophore/Polymer Composite Films

Abstract

In-depth studies of chirality and circularly polarized luminescence (CPL) have become indispensable in the process of learning human nature. Small molecules with CPL activity are one of the research hotspots. However, the CPL properties of such materials are generally not satisfying. Here, we synthesized a series of chiral small molecular fluorophores that cannot demonstrate CPL emission themselves. By introducing an optically inactive helical polymer, chirality transfer and chirality amplification efficiently occur, thereby generating intense CPL emission. Through combining different chiralized fluorophores, multicolor CPL-active films with emission wavelength centered at 463, 525, and 556 nm were fabricated, with the maximum luminescence dissymmetry factor (glum) being up to −0.028. Then, benefiting from the strong CPL emission and appropriate energy donor-acceptor system, we further established a circularly polarized fluorescence-energy transfer (CPF-ET) strategy in which the CPL-active films work as a donor emitting circularly polarized fluorescence to excite an achiral fluorophore (Nile red) as the acceptor, producing red CPL with glum of up to −0.011 at around 605 nm.