Supramolecular Chirality Suppresses Molecular Chirality: Selective Chiral Recognition in Hierarchically Coassembled Pyridine-Benzimidazole Conjugates with Precise ee% Detection.

Abstract

Incorporation of aromatic chiral species with axial, helical, or propeller chirality in surapmolecular chiral motifs would potentially facilitate the chiroptical applications such as enantiomeric excess detection, chiral sensing, and displays, which however suffer from inevitable competition between supramolecular chirality and molecular chirality and remain major challenges. Here, we show the programmable coassembly of pyridine-cored benzimidazole derivatives with intrinsic propeller chirality, which shall form binary and ternary aggregates with chiral acids as well as metal ions though H-bonds and metal-ligand coordination interactions in an orthogonal manner, to enhance and flexibly control the chiroptical properties. Solid-state X-ray structures of pyridine-benzimidazole derivatives suggested they adopted the propeller molecular chirality. Competition between molecular and supramolecular chirality and dynamic binding toward enantiomers of pyridine-benzimidazole derivatives was observed in the coassembly systems based on the chiroptical responses and molecular dynamic simulation. Compared to the intrinsic racemic assembly, coassembly systems produced chiroptical responses including the Cotton effect and circularly polarized luminescence (CPL) with relatively high dissymmetry factor (gabs up to 4.9 × 10-2, glum up to 9.6 × 10-3). Furthermore, chiroptical responses were further controlled by introducing metal ions, achieving inverted handedness and tunable dissymmetry factors. This work provides feasible strategies to efficiently regulate and enhance the chiroptical properties of intrinsic aromatics via multiple interactions, which also expressed great potential in quantitative ee% sensing for chiral acids.