Solvent Mediated Nanoscale Quasi‐Periodic Chirality Reversal in Self‐Assembled Molecular Networks Featuring Mirror Twin Boundaries

Abstract Grain boundaries in polycrystals have a prominent impact on the properties of a material, therefore stimulating the research on grain boundary engineering. Structure determination of grain boundaries of molecule‐based polycrystals with submolecular resolution remains elusive. Reducing the complexity to monolayers has the potential to simplify grain boundary engineering and may offer real‐space imaging with submolecular resolution using scanning tunneling microscopy (STM). Herein, the authors report the observation of quasi‐periodic nanoscale chirality switching in self‐assembled molecular networks, in combination with twinning, as revealed by STM at the liquid/solid interface. The width of the chiral domain structure peaks at 12–19 nm. Adjacent domains having opposite chirality are connected continuously through interdigitated alkoxy chains forming a 1D defect‐free domain border, reflecting a mirror twin boundary. Solvent co‐adsorption and the inherent conformational adaptability of the alkoxy chains turn out to be crucial factors in shaping grain boundaries. Moreover, the epitaxial interaction with the substrate plays a role in the nanoscale chirality reversal as well.