Water-Mediated Reconfigurable Topology and Mechanics in Porous Peptide Materials.

Biological systems, including proteins, employ water-mediated supramolecular interactions to adopt specific conformations to support their functions. Here, we present dynamic porous crystals of aliphatic dipeptides with sequence-isomers of variable conformational entropy (leucine (L) and isoleucine (I)) exhibiting shallow-energy landscapes, with various reconfigurable topologies and consequent mechanics accessible through changes in relative humidity and temperature. Specifically, for LI crystals, changes in water chemical potential cause the solid-state porous architecture to reorganize and reversibly transition between perpendicular and parallel honeycomb structures, as well as layered van der Waals structures, leading to significant and distinct variations in macroscopic morphologies, mechanical properties, and photophysical properties. These dynamic crystals are achieved by leveraging non-directional side-chain interactions with confined water, which drive the phase transition while stabilizing the structures. Our findings highlight the potential of minimalistic peptide designs, inspired by protein architecture, to create dynamic solid-state materials that adjust their properties in response to environmental stimuli.