Controlling Ultra‐Large Optical Asymmetry in Amorphous Molecular Aggregations

Although ultra-large optical asymmetry appears in crystalline materials, distractions from the mesoscopic ordering often causes inauthenticity in chiropticity. In addition, the formation and maintenance of crystalline states require complicated technical efforts. In amorphous materials, however, it remained challenging and elusive to achieve large chiropticity, not to mention the control of the degree of asymmetry. Herein, we report the quantitative control of chiral amplification, on amorphous supramolecular structures of cholesteryl-linked bis(dipyrrinato)zinc(II), to an exceptionally high level. The amorphous molecular aggregations of these complex building blocks exhibit mirror-image chiropticity. A proper chiral packing of the building block at several molecular scale contributes considerably to the absorptive dissymmetry factor g abs , although the system is overall disordered. The intense and tunable aggregation strength renders a variable g abs value up to +0.10 and +0.31 in the solution and in film state, higher than those observed in most previously reported cases. On this basis, a superior ON-OFF switching of chiropticity is realized under external stimuli. By eliminating the demand on material crystallinity, this work establishes a general design principle to control over ultra-large optical asymmetry on a wider scope of chiral materials.