For the optimization of the TD approach (Figure , A), imidazolium salts 1 and the corresponding masked NHC 1' were employed as a model system to mitigate unwanted side reactions caused by the azide moiety in 2 and 2', respectively. As precursor AuNPs, AuNPs with loosely bound oleylamine (OAm@AuNPs, see ESI for synthesis details) were used. Ligand exchange processes as well as PEG-NHC@AuNPs purified by dialysis against H2O were closely investigated by multinuclear NMR spectroscopy, FT-IR, X-ray photoelectron spectroscopy (XPS) analysis, ultraviolet-visible (UV-Vis) spectroscopy and transmission electron microscopy (TEM).