Peptide Crystal Hydrates with Context-Adaptive Topology

Biological systems, including proteins, employ water-mediated supramolecular interactions to adopt specific conformations for their functions. We present a minimalistic approach to capture this behavior, using crystal-hydrates of aliphatic dipeptides with sequence-isomers of leucine (L) and isoleucine (I). These crystals exhibit shallow conformational energy landscapes, with various reconfigurable crystal architectures accessible through changes in sequence, relative humidity, and temperature. Specifically, for LI crystals, as water content changes, the solid-state supramolecular architecture rapidly and reversibly transitions between perpendicular and parallel honeycomb architectures, as well as layered van der Waals structures, leading to significant variations in mechanical and photophysical properties. Our findings demonstrate the potential of leveraging aliphatic hydrophobic domains, inspired by protein architectures, to create dynamic solid-state materials with context-adaptive properties.