Thermodynamic Control of 2D Bicomponent Porous Networks of Melamine and Melem: Diverse Hydrogen-Bonded Networks

Different bicomponent self-assembled structures comprising melamine and melem were formed at aqueous solution–Au(111) interfaces by varying the concentrations of melamine and melem and the electrochemical potential. The structures were observed by in situ scanning tunneling microscopy. The structures of the bicomponent networks were controlled thermodynamically through the surface concentration and the molecular ratio. Interestingly, the solution concentration did not directly reflect the surface density of the self-assembled structures because of the flocculation-like behavior around the interface. Furthermore, structural phase transitions between the melem monocomponent honeycomb network, the bicomponent honeycomb network, and the melamine monocomponent honeycomb network with aggregates were directly and reversibly observed by controlling the electrochemical potential