Diverse Self-assembly Structures of a Macrocycle Revealed with STM by Adjusting the Solution Concentration

The macrocyclic molecule [3]C12TT-TPA was synthesized by a Stille coupling reaction through alternately connecting 4,7-bisthienyl-2,1,3-thienothiazole and triphenylamine units. The concentration-dependent self-assembly structures of [3]C12TT-TPA were explored in liquid/solid interface by scanning tunneling microscopy and density functional theory. After increasing the solution concentration, five different nanostructures were constructed and the molecular packing densities were gradually enhanced. Those structural transformations from loose structures to compact structures are thermodynamically favourable because those transformations are accompanied by the adsorption of more [3]C12TT-TPA molecules from liquid phase, which increases the interactions between molecules and the interactions between molecules and substrate considerably. This study of fundamental exploration is important to understand the basic formation mechanisms and the stability of two-dimensional functional materials.

Automated summary

By utilizing scanning tunneling microscopy and density functional theory, the concentration-dependent self-assembly structures of [3]C12TT-TPA at the liquid/solid interface were explored. Increasing the solution concentration led to the construction of five different nanostructures with gradually enhanced molecular packing densities. The study provides insight into the formation mechanisms and stability of two-dimensional functional materials.