Supramolecular-Covalent Hybrid Chiral Polymers with Strong Circular Dichroism and Unattenuated Dynamic Spectral Shift.

Abstract

Optically active chiral polymers have been fuelling advances in chiroptics, optoelectronics and sensors. However, achieving strong circular dichroism (CD) intensity and highly tunable chiroptical responses remains a critical yet challenging goal for chiral polymers. Here we report a supramolecular-covalent hybrid chiral polymer that exhibits dynamically tunable CD spectra with large spectral shifts while retaining high intensity. Supramolecular polymerization of a two-chain chiral monomer in solution yields gels composed of twisted fibrils of stacked nanoribbons. The diacetylene groups on the monomer chains align in long-range chiral order and undergo in situ topochemical polymerization, resulting in a supramolecular-covalent hybrid polymer. The polymer material appears dark blue and displays strong CD exceeding 1° at 670 nm. Remarkably, along with a blue-to-red chromatic transition upon heating, the CD peak shifts to 565 nm without attenuation of its magnitude. Mechanism study indicates the covalent polymer with a heat-responsive conjugated backbone is responsible for the dynamic spectral shift, whereas the supramolecular polymer contributes to the persistent high intensity. The unusual CD responses enable the use of the polymer in high-security information storage based on circular polarizations. The integration of supramolecular and covalent polymerizations provides strategies to create functional chiral polymers for advanced optical applications and beyond.