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 Xray 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 (g abs up to 4.9 × 10 −2 , g lum 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.

Arene–perfluoroarene interaction induced chiroptical inversion and precise ee% detection of chiral acids in a benzimidazole-involved ternary coassembly

“…According to our previous report, PBI may form strong intermolecular hydrogen bonds with chiral acids in water, whereby the chirality transfer from the chiral acids to PBI can be achieved. 30 In this work, tartaric acid ( TA ) and malic acid ( MA ) were chosen as chirality sources. In order to trigger the co-assembly, PBI and the chiral acids ( TA and MA ) were dissolved in dimethyl sulfoxide (DMSO) and deionized water as concentrated stock solutions (100 mM), respectively.…”

“…This phenomenon can be ascribed to the chiroptical properties that have no absolute correlation to the configuration of different chiral acids, in accordance with our previous report. 30…”

Folded Propeller Chiral Structures Exclusively Adaptive to Chloroform

“…Benzimidazole planes were conjugated onto the 2,6-position of a pyridine core, constituting into a rotatable aryl skeleton BI (Scheme b). A single crystal profile indicated BI has the propensity as P - and M -handed propeller chiral conformations with symmetry breaking . Further modification of diamino acid arms on imidazole afforded an intramolecular hydrogen bond between the amide groups which enables the transfer of chirality from amino acid to aryl skeleton both in the solid and solution state.…”

Multi-TpyCo2+-based conductive supramolecular hydrogels constructed by “bridge bonds” for rechargeable Zn-air batteries with ultrastable cycling stability over 1100 h

“…LMWGs signicantly change the construction model of gels, providing supramolecular gels with attractive physicochemical properties. 21,22 Currently, the commonly used LMWGs includes ferrocene, 23,24 pyridyl groups, 25,26 dipeptides, 27,28 avonoids, 29 etc. By coordinating the gelator installed with organic ligands and metal ions, metallohydrogels can be constructed conveniently and efficiently.…”