Chiral Toroids and Tendril Superstructures from Integrated Ternary Species with Consecutively Tunable Supramolecular Chirality and Circularly Polarized Luminescence
Many plant tendrils coil into helices which further exhibit terminal-spiral behavior into toroids. In this work, we illustrate the occurrence of such behavior at nano- and microscale whereby nanohelices feature tendril coil-type terminal-cyclization, allowing for the co-existence of toroid-terminated helical superstructures and independent chiral nanotoroids. Multiple-component coassembly was employed to magnify the chirality evolution from molecular to macroscopic scale, enabling a consecutively varied supramolecular chirality inversion expressing on Cotton effects, circularly polarized luminescence (CPL) and macroscopic handedness of superstructures. N-terminal aryl serine derivatives were noncovalently bound to distinct species via charge-transfer and duplex H-bonds, which diminished the unfavorable competitive pathways and facilitated a ternary coassembly route. Hierarchical and modularized coassembly from one to three species witnessed the consecutive chirality inversion, which enabled the flexible chiroptical manipulation including Cotton effects and CPL. Spring-like helices by coassembly demonstrates terminal-spiral behavior, allowing for the formation of heterojunction-like superstructures, which shares similar process to the tendril coiling. Due to the specific cyclization behavior, the affiliated and independent toroidal structures share identical chirality to helices. Such ternary coassembly affords a modularized and precise protocol to noncovalently synthesize soft topological structures with fine tailored CPL handedness, dissymmetry factor and luminescent colors.