1D Self-Assembly Formed by Dicyano[7]H Molecules with Cu Adatoms on Au(111) Aligned by Noncovalent Interactions

Abstract

The supramolecular self-assembly of 6,13-dicyano[7]helicene (dicyano[7]H) molecules has been theoretically studied on the Au(111) surface, both alone and with Cu adatoms, using computational methods to explain the types of interactions and cohesion within the structures previously observed by scanning tunneling microscopy (STM). When adsorbed alone, the dicyano[7]H molecules form chiral chains stabilized by hydrogen bonding and van der Waals (vdW) interactions. The coadsorption of these molecules with Cu atoms introduces additional electrostatic interactions. Through calculations and analysis of partial charges, interaction energy, and calculated STM images, we clarify the delicate balance of noncovalent interactions within the formed nanostructures. We also demonstrate that the interactions between Cu adatoms and dicyano[7]H molecules can be used to design stable one-dimensional chains on a metallic substrate driven by vdW forces, hydrogen bonds, and electrostatic forces. Notably, the Cu atoms do not form metal–organic coordination bonds but instead engage in electrostatic interactions with the C–N groups of the molecules through partial charges. These findings highlight that the coadsorption of organic molecules with metallic atoms is a promising approach for building well-ordered supramolecular networks on surfaces, mediated by noncovalent interactions such as hydrogen bonding, vdW forces, and electrostatic effects.