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Structural Water-Enabled Helicity Emergence From an Asymmetric Achiral Molecule
Hao Kong1, Zhen Wu1, Bijun Wang1
1State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, P. R. China.
Angewandte Chemie (International Ed. in English)
|August 8, 2026
Summary
Structural water enables the self-assembly of helical fibers from achiral molecules by acting as a symmetry breaker. This discovery offers new pathways for designing complex helical structures and controlling chirality.
Area of Science:
- Supramolecular chemistry
- Materials science
- Chemical self-assembly
Background:
- Helical supramolecular architectures are common in nature but difficult to create using simple achiral molecules.
- Controlling self-assembly pathways remains a significant challenge in synthetic chemistry.
Purpose of the Study:
- To investigate the role of structural water in directing the self-assembly of asymmetric achiral molecules into helical structures.
- To explore water's function as a symmetry-breaking element in artificial self-assembly.
Main Methods:
- Utilized an asymmetric achiral naphthalene derivative (N1) as a model system.
- Performed self-assembly experiments under varying hydration conditions (trace water vs. anhydrous).
- Employed single-crystal X-ray diffraction to analyze the molecular structure and hydrogen-bonding network.
Main Results:
- Trace structural water induced the formation of racemic P/M helical fibers from N1.
- Anhydrous conditions or control molecules lacking hydrogen-bonding capability resulted in non-helical aggregates.
- Water molecules acted as tetravalent nodes, forming C2-symmetric tetramers that introduced packing frustration, leading to helical twisting.
- Acid-base stimuli reversibly modulated the hydrogen-bonding network, controlling helical and non-helical morphologies.
- Chiral aromatic amino acids induced homochiral states in the helices, demonstrating a water-gated chirality transfer mechanism.
Conclusions:
- Structural water is a key element in breaking symmetry and inducing frustration for the self-assembly of helical structures from achiral molecules.
- This finding expands design principles for supramolecular helicity beyond symmetric monomers.
- Highlights the critical role of water in directing complex self-assembly pathways and enabling chirality transfer.
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