Enantiopure Assembly of M4L6 Supramolecular Clusters with Different Sizes and their Application to Asymmetric Organic Reactions

• Applicant: Dr. Nicola Alzakhem
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 260132063

In the past decades, the performance of reactions constrained within the cavity of supramolecular structures has emerged as a novel approach toward selective catalytic systems. Initially reported in 1998, Raymond and co-worker synthesized a supramolecular host complex having [Ga4L6]12- stoichiometry. This assembly has been employed as a supramolecular catalyst resulting in increased reaction rates and improved selectivity. However, despite the versatility of this class of catalysts, their application in asymmetric catalysis remains an important goal. In close collaboration with Professor Robert Bergman and Professor Dean Toste, I am working on two projects in the group of Professor Raymond to extend this rich chemistry of M4L6 tetrahedron. I successfully synthesized a novel enantiopure ligand which incorporates amino acids in its backbone. Structural and catalytic studies of the corresponding larger and enantiopure tetrahedron are currently under investigation. In the second project, the less established chemistry of the reduced charge self-assemblies [Ti4L6]8- and [Ge4L6]8- are explored. Both cluster were successfully synthesized and a microwave -assisted self-assembly procedure was used for the first time to synthesize the Ti4L6 tetrahedron. In order to compare the catalytic efficiencies of [Ge4L6]8- and [Ga4L6]12-, a supramolecular-mediated Aza-Cope rearrangement as model reaction is currently underway. This will answer the yet open question whether the charge of supramolecular cage influences its catalytic efficiency.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Kenneth N. Raymond