The Great Potential Of Redox Active Ligands

Metal N-heterocyclic carbene (NHC) complexes have recently gained much popularity due to their tunable, steric, and electronic properties. Applications for such versatile molecules include organocatalysis1 2 3, olefin metathesis4 5 6, sundry cyclization reactions7 8 9, and materials chemistry10 11. Redox active NHCs are of special interest due to their ability to alter the electronic properties of the metal centers they are ligated to.12 In the first chapter, Au(I)-NHC complexes were synthesized and tested for biological activity in human cancer cell lines. Increasing reactive oxygen species (ROS) in cellular systems has proven to be a successful pathway for treating cancer13 14 15. The redox active group in this case was naphthoquinone which contributed to the oxidative stress applied to the tumor cells. Three Au(I)-NHC complexes were synthesized and analyzed structurally utilizing 1H NMR, 13C NMR, and X-ray crystallography. Biological studies including IC50 cell culture lines and cell proliferation analyses were performed to determine the complexes' efficiency and success as a cancer treatment drug. The second chapter describes a theoretical approach to synthesize a redox active tetrathiafulvalene (TTF) fused with an iridium-NHC complex to serve as a redox switchable catalyst. The first compound in this synthetic route was successfully synthesized and analyzed structurally with 1H and 13C NMR, UV-Vis spectroscopy, and IR spectroscopy. The electrochemical properties were also investigated. Tetrathiafulvalene possesses the ability to undergo multiple one electron reversible redox transformations. This unique characteristic paired with the catalytic properties of iridium-NHC could produce a catalyst capable of accessing three or more catalytic species based upon the oxidation state of TTF.