Application in Anion Sensing and Transport
Our group has established a tradition in the chemistry of Lewis acidic organo-main group compounds that we have used for the construction of supramolecular structures as well as for the complexation of small anions including fluoride and cyanide. The main classes of compounds uncovered by our studies include organoboranes decorated by cationic functionalities such as ammonium or phosphonium groups as well as neutral and cationic antimony and tellurium compounds. As demonstrated in several publications, these derivatives can be used in water for the sequestration and sensing of a range of anions including fluoride and cyanide. Our most recent efforts suggest that cationic examples of the above-mentioned compounds promote efficient anion transport through artificial and biological membranes, opening the door to a range of applications including biological ones.
Carbenium Ion Chemistry
Over the years, we have had a sustained interest in the synthesis and study of main group compounds featuring Lewis acidic and electroactive carbenium functionalities. These efforts have led to the isolation of naphthalene-based dications, α-borylated carbenium ions as well as phosphonium-carbenium dications. In a recent extension of this chemistry, we have become interested in the possibility of using carbenium ions as Z-type ligands, a possibility supported by our recently published work on the synthesis and catalytic properties of derivatives with weak Au->C+ interactions.
Exploiting the Non-innocence of Antimony Ligands: From Organometallic Catalysis to the Photoreductive Elimination of Halogens
Although often regarded as heavy phosphine analogs, stibines behave as non-innocent ligands and display an unusual reactivity even when ligated to transition metals (M). This reactivity comes to light in their ability to undergo oxidation reactions without dissociation of the coordinated transition metal. This oxidation induces the formation of a M->Sb interaction resulting in a drastic Lewis acidity increase at the transition metal center. Using a family of gold stibine derivatives, we have demonstrated that such coordinated-stibine oxidation reactions can be used to afford potent hydroamination catalysts. Stibines are also non-innocent from a coordination point of view and can readily bind hard anions such as fluoride, without dissociation from the transition metal center. These anion binding events convert the antimony atom into a more strongly donating ligand, leading to an increase of electron density at the metal center. Our recent studies of these ligand-based coordination processes have shown that they can be exploited in reverse as a means to increase the electrophilic character of the transition metal center. This approach is illustrated by our work on antimony-platinum complexes and their conversion into active electrophilic hydroarylation and enyne cyclization catalysts via antimony-centered anion abstraction reactions. Finally, we are also interested in the photochemistry of M-Sb complexes with a special focus on systems that support antimony-centered photoreductive processes.