Solvent effects on two-dimensional molecular self-assemblies investigated by using scanning tunneling microscopy

Self-assembly structures investigated by using scanning tunneling microscopy (STM) at liquid/solid interface have been a topic of broad interest in surface science, molecular materials, molecular electronics. The delicate balance among the adsorbate–solvent, adsorbate–adsorbate, solvent–solvent interactions would give rise to the coadsorption or competitive deposition of solvent with adsorbate. The solvents at the interface enable dynamic absorption and desorption of the adsorbates leading to the controlled assembly of the molecular architectures. The solvent-induced polymorphism, coadsorption effect, as well as solvent effects on chirality and electronic structures are discussed in this report in view of the polarity, solubility and viscosity of the solvent, the hydrogen bonding formation between solute and solvent, and the solvophobic and solvophilic effects. The systematic studies on the solvent effects would shed light on better control of assembly structures for design of new molecular materials and molecular electronics.