Novel Catalytic Transformations of Organoboron Species and the Development of Ultrastable Self-Assembled Monolayers on Metal Surfaces

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The proposed research is based on two exciting discoveries from our lab. In 2014, we demonstrated that NHCs form monolayers on gold that withstand unprecedented extremes of heat, oxidant, acid and base. This work was called "game changing" by international experts, including Hä kkinen, director of the Nanoscience Centre in Finland. Other experts called it "the new gold standard" and "elegant". NHCs have been known to form strong bonds in transition metal complexes but had not previously been examined as alternatives to thiols for self-assembled monolayers on metals. In this proposal, we will explore many aspects of this novel and exciting discovery, including: (1) the effect of NHC structure on film quality and bond strength, (2) the use of NHCs to form films on other metals including Ag and Cu where the NHC coating may help prevent oxidation and tarnishing, and (3) the use of NHCs in magic number Au clusters, which are remarkable molecular materials, that have been largely prepared with thiol ligands and thus NHCs will provide a completely new type of nanomaterial. In long term goals, we will (4) explore the use of NHCs in molecular electronics and as modifiers for catalytically active surfaces and nanoparticles. Many collaborations for this project are already in place, including with Horton (surface science, Queen's), McLean (STM imaging, Queen's Physics), Baddeley (STM imaging, St. Andrews), Kraatz (Electrochemistry, U of T Scar.), Hä kkinen (Theory, Finland), Mosey (Theory, Queen's) and Tsukuda (nanoclusters, Japan). The second part of this proposal builds on recent discoveries in catalysis, where we demonstrated that organic molecules with practically identical boron substituents can undergo selective, orthogonal coupling by manipulating the ability of the C-B bond to transmetalate to Pd. This back-to-back Suzuki coupling without protecting groups had never been accomplished prior to our Nature Comm. paper (in revision). In this grant, we will study the control elements in the stereochemistry of the transmetalation reaction. We will employ more complex coupling partners containing both a nucleophile and an electrophile, and will study deborylation as a completely novel method for the preparation of chiral boron compounds as critical starting materials for this transformation. Aspects of this project will be collaborative with Chirik (Princeton). Student salaries are 70% of the proposed budget, representing my significant commitment to training. The proposed chemistry is even more multidisciplinary than previous projects and thus funds are allocated for collaborative visits. I plan to continue to provide all PhD students the opportunity to carry out research abroad during their degree. This has been highly successful for broadening the experience of my HQP, forming international networks and making contacts for future job/PDF positions.