Search for: All records

Two stereoisomers, one C₂ symmetric and one C_s symmetric, of saturated N-heterocyclic carbenes (NHCs) were placed on gold films and they demonstrate different reactivity. 

The discovery of N-heterocyclic carbenes (NHCs) revolutionized organometallic chemistry due to their strong metal–ligand bonds. These strong bonds also lend enhanced stability to gold surfaces and nanoparticles. This stability and high degree of synthetic tunability has allowed NHCs to supplant thiols as the ligand of choice when functionalizing gold surfaces. This review article summarizes the basic science and applications of NHCs on gold surfaces and gold nanoparticles. Additionally, scientific questions that are unique to gold–NHC systems are discussed, such as the NHC adatom binding motif and the NHC surface mobility. Finally, new applications for NHCs on gold are covered with particular attention to biomedicine, catalysis, and microelectronics. 

Abstract The widespread application of laser desorption/ionization mass spectrometry (LDI‐MS) highlights the need for a bright and multiplexable labeling platform. While ligand‐capped Au nanoparticles (AuNPs) have emerged as a promising LDI‐MS contrast agent, the predominant thiol ligands suffer from low ion yields and extensive fragmentation. In this work, we develop a N‐heterocyclic carbene (NHC) ligand platform that enhances AuNP LDI‐MS performance. NHC scaffolds are tuned to generate barcoded AuNPs which, when benchmarked against thiol‐AuNPs, are bright mass tags and form unfragmented ions in high yield. To illustrate the transformative potential of NHC ligands, the mass tags were employed in three orthogonal applications: monitoring a bioconjugation reaction, performing multiplexed imaging, and storing and reading encoded information. These results demonstrate that NHC‐nanoparticle systems are an ideal platform for LDI‐MS and greatly broaden the scope of nanoparticle contrast agents.