THE ROLE OF COMPETITION EFFECT IN THE SELF-ASSEMBLY STRUCTURE OF 3,5-DIPHENYLBENZOIC ACID AND 2,2′:6′,2″-TERPYRIDINE-4′-CARBOXYLIC ACID ON Ag(110)

The self-assembly structures of 2,2′:6′,2′′-terpyridine-4′-carboxylic acid (C16H11N3O2; YN) molecules and 3,5-diphenylbenzoic acid (C19H14O2; YC) molecules on Ag(110) surface have been investigated by scanning tunneling microscopy (STM) and Density Functional Theory (DFT) calculation. The YC molecules form two different well-organized structures due to the π–π stacking and dipole–dipole interactions. When three C atoms of YC molecules are replaced by three N atoms to form YN molecules, the main driving force to form ordered assembly structures of YN molecule is changed to metal–organic coordination bond and hydrogen bond. The dramatic changes of main driving force between YC/Ag(110) and YN/Ag(110) system demonstrate that the N atoms are apt to form metal–organic coordination bond and hydrogen bond but dipole–dipole interactions and π–π stacking are relative to C atoms. These findings further reveal that the optimization design of organic molecules could vary the main driving force and then lead to the change of the molecular self-assembly structures.