Supramolecular Cl×××H and O×××H interactions in self-assembled 1,5-dichloroanthraquinone layers on Au(111)

The role of halogen bonds in self-assembled networks for systems with Br and I ligands has recently been studied with scanning tunneling microscopy (STM), which provides physical insight at the atomic scale. Here, we study the supramolecular interactions of 1,5-dichloroanthraquinone molecules on Au(111), including Cl ligands, by using STM. Two different molecular structures of chevron and square networks are observed, and their molecular models are proposed. Both molecular structures are stabilized by intermolecular Cl×××H and O×××H hydrogen bonds with marginal contributions from Cl-related halogen bonds, as revealed by density functional theory calculations. Our study shows that, in contrast to Br- and I-related halogen bonds, Cl-related halogen bonds weakly contribute to the molecular structure due to a modest positive potential (σ hole) of the Cl ligands. Halogen interaction: Supramolecular interactions in the two-dimensional self-assembled layers of 1,5-dichloroanthraquinones on Au(111) are studied using scanning tunneling microscopy and density functional calculations. Intermolecular Cl×××H and O×××H hydrogen bonds stabilize two different molecular structures. Cl-related halogen bonds marginally contribute to this stabilization due to the modest positive potential (σ hole) of the Cl ligands.