Exposing the Dynamics and Energetics of the N-Heterocyclic Carbene-Nanocrystal Interface.

N-Heterocyclic carbenes (NHCs) are becoming increasingly popular ligand frameworks for nanocrystal surfaces; however, as of yet the nature of the NHC-nanocrystal interface remains unexplored across different material types. Here we report a facile synthetic route to NHC-stabilized metal and metal chalcogenide nanocrystals. It was observed that NHC-Ag nanocrystals are colloidally stable, but much less so than the corresponding NHC-AgE analogues. Comprehensive NMR studies suggest a dynamic NHC-nanocrystal interface for both NHC-Ag and NHC-AgS; however, density functional theory calculations reveal a much stronger binding affinity of the NHC ligands to AgS compared with Ag nanocrystals, which explains the superior colloidal stability of the metal chalcogenides. This offers new insight into the surface chemistry of neutral L-type carbenes in colloidal nanocrystal chemistry.