Fundamentals and applications of N-heterocyclic carbene functionalized gold surfaces and nanoparticles

Abstract

Improved stability and higher degree of synthetic tunability has allowed N-heterocyclic carbenes to supplant thiols as ligands for gold surface functionalization. This review article summarizes the basic science and applications of NHCs on gold.

Stability of N-Heterocyclic Carbene Monolayers under Continuous Voltammetric Interrogation

“…Changes in sterics and electronics due to the ester functionalization of the NHC backbone provide a comparison of electrochemical stability between the two related NHCs. Finally, the NHC-ester works as a simple model ligand toward the kinds of NHCs that could be post-synthetically modified for amide-coupling reactions. , …”

“…Finally, the NHCester works as a simple model ligand toward the kinds of NHCs that could be post-synthetically modified for amidecoupling reactions. 21,24 ■ RESULTS AND DISCUSSION N-Heterocyclic Carbenes Spontaneously Adsorb on the Surface of Gold Electrodes. A joint approach of electrochemical and spectroscopic methods was used to evaluate the spontaneous formation of NHC monolayers.…”

New class of RSO2-NHC ligands and Pd/RSO2-NHC complexes with tailored electronic properties and high performance in catalytic C–C and C–N bonds formation

“…N,N′-Diarylated imidazolium salts are widely used as precursors of N-heterocyclic carbene (NHC) ligands and metal nanoparticle stabilizers in organometallic chemistry, [1][2][3] metal catalysis, [4][5][6][7][8][9][10][11] and material sciences. [4][5][6][12][13][14][15][16][17][18] NHCs of the imidazole type formally produced via deprotonation of the C(2)-H moiety of imidazolium salts are currently one of the most indemand types of ligand in metal/NHC catalysis.…”

Using Surface-Enhanced Raman Spectroscopy to Unravel the Wingtip-Dependent Orientation of N-Heterocyclic Carbenes on Gold Nanoparticles

“…Dense, ordered, self-assembled monolayers (SAMs) on noble-metal surfaces are a prerequisite for many applications in sensing, − catalysis, − and electronics. , While thiols have been the ligand of choice for many decades now, N-heterocyclic carbenes (NHCs) recently emerged as an attractive alternative as they form strong σ-bonds to transition metals and well-ordered SAMs on metal surfaces. − When compared to thiol-SAMs, NHC-SAMs deliver superior performance in a range of thermal, chemical, and biological conditions; − however, the formation and stability of NHC monolayers are highly dependent on the NHC structure . For example, the NHC wingtip groups, i.e., the groups attached to the NHC nitrogens, provide steric interactions that can modify the surface packing and orientation .…”