Enantioselective Induction, Amplification, and Storage of Helical Chirality in Absolutely Achiral Polymer Systems

As one of the most challenging scientific issues in the world, the origin of natural homochirality has attracted intense attention and has been widely studied. Herein, a unique, simple, and scalable approach to achieve the birth of helical chirality is presented. In the absence of any additional physical or chemical chiral source, optical activity has been acquired in the absolutely achiral polymer casting systems. Specifically, optically active and recyclable composite films are fabricated from casting racemic helical substituted polyacetylenes and achiral polar polymeric matrices. The induced dissymmetry intensity can be flexibly adjusted by controlling the temperature for fabricating the films and/or the recycling casting times. This study reveals that weak intermolecular interactions can enantioselectively drive racemic helices to be far from the original equilibrium state, thereby resulting in the generation of helical chirality that can be further amplified and maintained in solid films. To demonstrate the utility of the as-obtained chiroptical films, circularly polarized luminescence (CPL) has been achieved by judiciously combining an achiral fluorescent source with the casting films. The finding of symmetry breaking at the macromolecular level can provide useful insights into the understanding of natural homochirality and the design of chiral functional materials.