Ambient Tunneling Microscopy of Surface Annealing and Ligand Exchange Reactions on Metal–Organic Chalcogenolates

We introduce the use of scanning tunneling microscopy (STM) on microcrystalline metal-organic chalcogenolates (MOChas). We demonstrate the suitability of these compounds as STM substrates directly after drop casting onto graphitic surfaces, followed by chemical treatment. We successfully imaged 1-dimensional (1D) silver(I) methyl 2-mercaptobenzoate (2MMB) and the archetypical 2-dimensional (2D) MOCha, silver(I) benzeneselenolate (mithrene). The resolution afforded by STM was used to make new insights into the surface chemistry and displacement reactions. We observed the annealing and displacement reactions of mithrene and 2MMB and the transformation of the former into 2D silver(I) n-nonaneselenolate. MOCha crystals are amenable to STM imaging directly as-prepared from powders, despite the presence of its insulating organic units. We observed defects, crystal growth dynamics, and the formation of grains and superstructures. Visualizing such topographical heterogeneities could prove vital for understanding bulk functionality in this optoelectronic material class.