A new project in our group revolves around the study of the use of N-heterocyclic carbenes (NHCs) as ligands for gold surfaces. In 2014, we described the first example of well-formed NHC monolayers on gold surfaces. Despite their widespread use in catalysis, NHCs have seen remarkably few applications in materials chemistry. In molecular complexes, these species are known to provide considerably greater stability to the metal centres than traditional ligands, due in part to the strong metal–carbon bond. These molecular complexes are more resistant to heat and oxidation than related phosphine complexes. Assuming that these properties would translate to materials, we examined the ability of NHCs to form bonds to gold surfaces.
Indeed it turned out that self–assembled monolayers of NHCs on gold formed easily and were significantly more stable than the state-of-the-art thiol-based films. These monolayers can be imaged by STM and other techniques. The NHC films are stable to high temperature, refluxing organic solvent, high temperature acid, base and oxidation with dilute hydrogen peroxide.
Applications of this work are currently being extensively explored, and include automotive, bio-sensing, cancer detection and chemotherapy and clean energy. Stay tuned for more exciting stuff from this project!
This work was highlighted in Chemistry and Physics news magazines around the world including Physics Today, Chemistry World (RSC), Chemical and Engineering News, Canadian Chemistry News, Science Media Centre Canada, and others, and called “Game changing”, “the new gold standard”, and “elegant”.
C.M. Crudden, J.H. Horton, I.I. Ebralidze, O.V. Zenkina, A.B. McLean, B. Drevniok, Z. She, H.-B. Kraatz, N.J. Mosey, T. Seki, E.C. Keske, J.D. Leake, A. Rousina-Webb, G. Wu, “Ultra Stable Self-Assembled Monolayers of N-Heterocyclic Carbenes on Gold” Nature Chemistry, 2014, 6,409-414.