Direct Imaging of Individual Organic Molecules in Supramolecular Assembly Strongly Fixed via Multivalent Electrostatic Interactions

Recent developments in electron microscopy and novel techniques for the precise control of low-dimensional substrate materials have led to the emergence of direct imaging of organic molecules. However, supramolecular assemblies constructed via noncovalent interactions are structurally unstable under electron beam irradiation. This study focused on a supramolecular assembly of well-isolated organic molecules based on multivalent electrostatic interactions, where anionically charged clay mineral nanosheets were used as a host material. Direct imaging of the single organic molecules and supramolecular assemblies on the monolayer clay mineral nanosheets was achieved via annular dark field scanning transmission electron microscopy using heavy metal atom markers. The versatility of multivalent electrostatic interactions for the stable fixation of organic molecules during electron microscopic imaging was demonstrated. This strategy can be applied to a wide range of supramolecular systems comprising various guest molecules and host materials, thereby broadening the scope of atomic-scale imaging.

Automated summary

Recent developments in electron microscopy and novel techniques have allowed for direct imaging of organic molecules, particularly supramolecular assemblies utilizing multivalent electrostatic interactions on anionically charged clay mineral nanosheets. The stable fixation of organic molecules during electron microscopic imaging was achieved through the utilization of heavy metal atom markers in annular dark field scanning transmission electron microscopy. This strategy demonstrates versatility and potential application in a wide range of supramolecular systems, enhancing atomic-scale imaging capabilities.