Adsorption And Self-assembly Of Conjugated Molecules On Metal Surface

High-resolution scanning tunneling microscopy (STM) observations unambiguously reveal the windmill-like chiral nature of individual ZnPc molecules on Cu(100) surface at room temperature. The combinations of STM observations, X-ray photoelectron spectroscopy (XPS) and density function theory (DFT) calculations suggest that such chirality is attributed to asymmetrical charge transfer between the molecules and the copper surface. Moreover, such chiral enantionmers not only can be conserved but also the chiral ZnPc molecules certainly recognize each other to form second-level supramolecular structures with the same chirality during thermally-driven movements. Chemical bond is considered to play an important role in chiral recognition of such orbital-specific chirality based on the analysis of the sub-molecule-resolution STM images.Structural phase transitions of4’-(4-carboxyphenyl)-2,2’:6’,2"-terpyridine molnolayer on Au(111) surface at various annealilng stages have been revealed by ultrahigh vacuum scanning tunneling microscopy (STM). The as-deposited monolayer is closed-packed but lack of long-range periodicity. A thermal annealing process gradually drives such disordered monolayer into metastable ordered state. Further annealing turns the metastable state into chain-like stable ordered state. Such phase transitions are attributed to the competition between Van der Wassl interactions, dipole-dipole interaction and hydrogen bond.