Steering the Interplay between Hydrogen and Coordination Bonds in Surface-Confined Molecular Assemblies

The interplay between hydrogen bonding and metal–ligand coordination plays a vital role in directing molecular network formation on surfaces, yet controlled regulation of this interplay remains challenging. Here, using scanning tunneling microscopy, we investigated the assembly of 1,3-bis(4-pyridyl)benzene molecules on Au(111) and Au(100) surfaces. We found that dense molecular packing favors hydrogen-bonded networks, while reduced coverage and thermal activation promote coordination motifs. In addition, Au(100) exhibits a stronger coordination tendency and better molecular size commensurability than those of Au(111), revealing pronounced surface facet effects. Further combined with thermal activation, we achieved dominant one-dimensional coordination chains on Au(100). Our findings demonstrate systematic control of intermolecular bond competition through molecular density, substrate crystallography, and thermal activation, establishing adaptable design principles for programmable surface-confined molecular architectures.