LEAPS-MPS: Heterogeneous Asymmetric Catalysis with Chiral Metal Clusters

In this project managed by the Chemistry Division at NSF, Professor Anindita Das and her students at Southern Methodist University will perform studies that aim to transpose ligand-directed asymmetric catalysis from homogeneous to heterogeneous systems by installing new chiral ligands on the surfaces of metal clusters. Asymmetric catalytic reactions represent a powerful way to synthesize optically active compounds which have tremendous implications in medicine. For instance, more than 75% of the small-molecule drugs approved by the FDA in the last 5 years are chiral compounds. Over the years, chemists have achieved tremendous success in developing homogeneous asymmetric organocatalysts as well as transition-metal complex catalysts by rationally designing chiral ligands which mimic the active sites of enzymes. However, using this strategy for industrially relevant heterogeneous metal nanoparticle-based catalysts to achieve “predictive heterogeneous asymmetric catalysis” is a longstanding challenge owing to the inherent polydispersity of nanoparticles synthesized by conventional routes. To address this limitation, Professor Das and her students will develop atomically precise model metal clusters the surfaces of which will feature new chiral ligands to tune their catalytic activity, analogous to homogeneous asymmetric catalysts. Their studies could help identify the critical parameters related to asymmetric catalytic activity of metal cluster-based model catalysts leading to better heterogeneous catalyst design in future. This research is integrated with numerous outreach activities to engage and encourage underrepresented, first-generation, or low-income students to pursue STEM degrees and careers. These include organizing workshops and demo-experiments at nearby high schools and MSIs to promote public literacy about science and research. Additionally, trainings on hidden implicit biases and cultivating cultural intelligence will be undertaken to create an inclusive and supportive lab environment. Professor Das and her students will synthesize and characterize a series of atomically precise metal clusters protected by new chiral ligands. The synthetic mechanisms of these clusters will be investigated by various techniques such as single crystal X-ray crystallography, NMR, UV-visible and fluorescence spectroscopy, circular dichroism (CD) spectroscopy, electrochemical analysis, and mass spectrometry. These synthetic guidelines will then be applied to bimetallic chiral metal clusters to study the effects of cooperative interactions in model asymmetric transformations. Ultimately, the design rules generated from this research may be broadly applied to other classes of heterogeneous nanomaterials to understand and tailor their asymmetric catalytic properties with atomic precision. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.