TY - JOUR
T1 - Ad aurum
T2 - tunable transfer of N-heterocyclic carbene complexes to gold surfaces
AU - Dominique, Nathaniel L.
AU - Chen, Ran
AU - Santos, Alyssa V.B.
AU - Strausser, Shelby L.
AU - Rauch, Theodore
AU - Kotseos, Chandler Q.
AU - Boggess, William C.
AU - Jensen, Lasse
AU - Jenkins, David M.
AU - Camden, Jon P.
N1 - Funding Information:
N. L. D. gratefully acknowledges the Berthiaume Institute at Notre Dame for summer fellowship funding. N. L. D. and J. P. C. thank the Notre Dame Mass Spectrometry and Proteomics Facility for use of the Bruker UltrafleXtreme and Bruker Impact II instruments; Alexander Mukasyan and Tatyana Orlova of the Notre Dame Integrated Imaging Facility for use of the Magellan 400 SEM; Mike Brueseke and Jon Loftus of the Notre Dame CEST facility for use of the BIC NanoBrook Omni instrument and ICP-OES instrument; and Anna Matzner and Ian Lightcap of the Notre Dame Materials Characterization Facility for use of the PHI VersaProbe II instrument.
Funding Information:
This work is supported by the National Science Foundation under grant numbers CHE-2108330 (N. L. D. and J. P. C.), CHE-2108328 (D. M. J.) and CHE-2106151 (R. C. and L. J.) and DGE 1255832 (A. V. B. S.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
Publisher Copyright:
© 2022 The Royal Society of Chemistry.
PY - 2022/10/17
Y1 - 2022/10/17
N2 - The exceptional stability of N-heterocyclic carbene (NHC) monolayers on gold surfaces and nanoparticles (AuNPs) is enabling new and diverse applications from catalysis to biomedicine. Our understanding of NHC reactivity at surfaces; however, is quite nascent when compared to the long and rich history of NHC ligands in organometallic chemistry. In this work, well-established transmetalation reactions, previously developed for NHC transfer in homogeneous organometallic systems, are explored to determine how they can be used to create carbene functionalized gold surfaces. Two classes of NHCs, based on imidazole and benzimidazole scaffolds, were tested. The resulting AuNP surfaces were analyzed using X-ray photoelectron spectroscopy (XPS), laser desorption ionization mass spectrometry (LDI-MS), and surface-enhanced Raman spectroscopy (SERS). Reaction of either a Au(i) or Ag(i) isopropyl benzimidazole NHC complex with citrate-capped AuNPs yields, in both cases, a chemisorbed NHC that is bound through a Au adatom. Theoretical calculations additionally illustrate that binding through the Au adatom is favored by more than 10 kcal mol−1, in good agreement with experiments. Surprisingly, reaction of Au(i), Ag(i), and Cu(i) diisopropylphenyl imidazole NHCs do not follow the same pattern. The Cu complex undergoes transmetalation with very little deposition of Cu; whereas, unexpectedly, the Ag complex foregoes transmetalation and instead adducts to the AuNP with retention of the Ag-C bond. Theoretical calculations illustrate that the imidazole ligand affords significant dispersion interactions with the gold surface, which may stabilize binding through the Ag adatom motif, despite its less favorable bonding energies. Taken together these results suggest a unique ability to tune the reactivity by changing the carbene structure and raise critical questions about how established transmetalation reactions in organometallic chemistry can be applied to form NHC functionalized surfaces.
AB - The exceptional stability of N-heterocyclic carbene (NHC) monolayers on gold surfaces and nanoparticles (AuNPs) is enabling new and diverse applications from catalysis to biomedicine. Our understanding of NHC reactivity at surfaces; however, is quite nascent when compared to the long and rich history of NHC ligands in organometallic chemistry. In this work, well-established transmetalation reactions, previously developed for NHC transfer in homogeneous organometallic systems, are explored to determine how they can be used to create carbene functionalized gold surfaces. Two classes of NHCs, based on imidazole and benzimidazole scaffolds, were tested. The resulting AuNP surfaces were analyzed using X-ray photoelectron spectroscopy (XPS), laser desorption ionization mass spectrometry (LDI-MS), and surface-enhanced Raman spectroscopy (SERS). Reaction of either a Au(i) or Ag(i) isopropyl benzimidazole NHC complex with citrate-capped AuNPs yields, in both cases, a chemisorbed NHC that is bound through a Au adatom. Theoretical calculations additionally illustrate that binding through the Au adatom is favored by more than 10 kcal mol−1, in good agreement with experiments. Surprisingly, reaction of Au(i), Ag(i), and Cu(i) diisopropylphenyl imidazole NHCs do not follow the same pattern. The Cu complex undergoes transmetalation with very little deposition of Cu; whereas, unexpectedly, the Ag complex foregoes transmetalation and instead adducts to the AuNP with retention of the Ag-C bond. Theoretical calculations illustrate that the imidazole ligand affords significant dispersion interactions with the gold surface, which may stabilize binding through the Ag adatom motif, despite its less favorable bonding energies. Taken together these results suggest a unique ability to tune the reactivity by changing the carbene structure and raise critical questions about how established transmetalation reactions in organometallic chemistry can be applied to form NHC functionalized surfaces.
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U2 - 10.1039/d2qi01941h
DO - 10.1039/d2qi01941h
M3 - Article
AN - SCOPUS:85141399232
SN - 2052-1545
VL - 9
SP - 6279
EP - 6287
JO - Inorganic Chemistry Frontiers
JF - Inorganic Chemistry Frontiers
IS - 23
ER -