Chiral Molecular Clamp Enabling Selective Chirality Transfer via Arene–Perfluoroarene Interactions

Abstract

The precise transfer of chirality from a molecular scaffold to an achiral guest in solution represents a fundamental challenge, because conformational dynamics often obscure stereochemical communication. We designed two chiral ferrocene-based compounds, Fc-2Ala and Fc-3Ala, differing by one methylene in the alkyl linker. Single-crystal X-ray diffraction reveals that Fc-3Ala, bearing a longer propylene linker, adopts a folded clamp-like conformation stabilized by intramolecular hydrogen bonds and π–π stacking. The shorter ethylene linker in Fc-2Ala prevents intramolecular π-stacking, resulting in extended w- or v-shaped hydrogen-bonded conformations. This structural divergence dictates chiroptical properties, recognition behavior, and supramolecular self-assembly morphologies. Spectroscopy and computation demonstrate that folded Fc-3Ala establishes a defined chiral microenvironment with electrostatic complementarity toward electron-rich aromatic guest, enabling effective chirality transfer, whereas nonfolded Fc-2Ala fails. The preorganized clamp also confers morphological robustness. Collectively, subtle linker variation controls molecular folding, offering a strategy for tunable chiral supramolecular platforms, chiroptical materials, and sensors.