ABSTRACT Water is conventionally viewed as a disruptive solvent for supramolecular materials, destabilizing directional noncovalent interactions. Here, we report a metal–organic material in which water instead acts as a structural co‐monomer driving the formation of supramolecular fibers. A zinc(II) bisphenoxyimine (“Salphen”) complex featuring convergent hydrogen‐bond acceptor sites assembles in bulk water into long, hollow nanofibers stabilized by confined structural water molecules. Single‐particle analysis and density functional theory reveal tubular architectures in which intercalated water bridges the metal centers and defines a hydrophilic inner channel. The fibers form hydrogels with thermomechanical response, chemically triggerable disassembly and enable selective chiral recognition of amino acids via water‐mediated molecular–to–supramolecular information transfer. In organic solvents, the water content can be used for control over supramolecular self‐assembly and hence gelation and liquefaction. Our findings establish structural water as a design element for creating adaptive, chiral, and dynamically reconfigurable metal–organic materials, offering a new paradigm to unlock this sustainable building block in supramolecular materials design.
Stühler et al. (2026) studied this question.