This study investigates the self-assembly of N-heterocyclic carbenes (NHCs) on gold and silver substrates with different crystalline facets. A marked difference in assembly is observed when transitioning from (111) to (100) facets. Additionally, surface reconstruction appears to significantly influence the assembly behavior. The work offers plausible explanations for the facet-dependent differences in molecular organization.

Due to its exceptional chemical and functional versatility, N-heterocyclic carbene chemistry holds great promise in replacing thiol chemistry for applications in next-generation nanoelectronics. To manipulate their chemical properties and interfacial characteristics, a wide range of substrates needs to be employed for the formation of self-assemblies. Research has, however, predominantly focused on the Au(111) substrate. Herein, a systematic approach is presented for producing long-range, densely packed self-assemblies using carbenes deposited over (111) and (100) crystalline facets of gold and silver single crystals. Atomic-resolution characterization with scanning tunneling microscopy (performed at 78 K and room temperature) is combined with the molecular structure, showing the role of distinct crystal facets in the ordering of self-assembled monolayers.