On-surface visualization of the influence of the chemical environment on halogen-hydrogen bonds at submolecular scale

The halogen-hydrogen bond has demonstrated remarkable potential in controlling molecular assembly and precisely steering reaction pathways on surfaces. However, few attempts have been devoted to explore the fundamental characteristics of halogen-hydrogen bonds in real space. Herein, we systematically investigate the influence of the local chemical environment of hydrogen atoms on halogen-hydrogen bonds. Combining high-resolution scanning tunneling microscopy investigations with density functional theory calculations, we clarify that tuning the chemical environment of hydrogen atoms varies corresponding halogen-hydrogen bonding strengths on the Ag(111) surface, leading to the formation of different two-dimensional tessellation patterns. Our studies provide real space insights into the mechanism of halogen-hydrogen bonds and establish a strategy for designing complex low-dimensional nanostructures on metal surfaces.