Engineering two-dimensional supramolecular self-assembly: The role of Cl atoms

Abstract

On-surface synthesis is a powerful tool for engineering two-dimensional (2D) organic nanostructures by controlling intermolecular interactions between the building blocks. Herein, we explore the role of Cl adatoms in the synthesis and characterization of self-assembled 1,3,5-tris[4-(pyridin)-[1,1’-biphenyl]benzene (TPyPPB) networks on Ag(111), by combining scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). In the absence of Cl, upon deposition at room temperature (RT), TPyPPB molecules form a highly ordered porous supramolecular network with triangular packing, stabilized by hydrogen bonds (N⋯H). In the presence of Cl adatoms, sublimated onto the surface using dichloro-(1,10-phenanthrolin)-platin(II) (Cl2PhPt) a second molecular precursor, we observe a so-called mixed phase or inverted packing, depending on the applied growth procedure. The mixed phase is characterized by a non-periodic structure stabilized by intermolecular interactions between TPyPPB, Cl2PhPt, and Cl. In contrast, when only Cl adatoms and TPyPPB are present on the Ag(111) surface, a non-porous supramolecular arrangement is obtained, stabilized by C–H⋯Cl hydrogen bonds.