Space Filling Interfacial Crystals

Abstract: We describe the discovery of a novel phenomenon, termed interfacial crystallization (IFC), in which halide salts of amidated single peptoid bases and amino acids form crystals at chemical interfaces. The IFC forming species, including ones containing only aliphatic chemical functionality, are space filling as they not only persist at the interface but ultimately fill it. The monomers selected for testing served to identify the key molecular design principles for IFC, and it is concluded that sidechain steric effects and their presumed impact on crystal packing controls the viability of a molecule’s IFC propensity. Additionally, a hypothesis to explain IFC growth, premised on ion migration to interfaces as being the crucial step to template growth, is proposed and validated. The aliphatic IFC supramolecular nanostructures are observed to form on the centimetre length scale, bounded only by the containers used, and this extended dimensionality further makes it a compelling discovery.