LEAPS-MPS: Heterogeneous Asymmetric Catalysis with Chiral Metal Clusters

在这项由NSF化学系管理的项目中，南卫理公会大学的Anindita Das教授和她的学生将进行研究，旨在通过在金属簇合物表面安装新的手性配体，将配体导向的不对称催化从均相体系转移到多相体系。不对称催化反应是合成光学活性化合物的一种强有力的方法，具有巨大的医学意义。例如，过去5年FDA批准的小分子药物中，超过75%是手性化合物。多年来，化学家们通过合理设计模拟酶活性中心的手性配体，在开发均相不对称有机催化剂和过渡金属络合物催化剂方面取得了巨大的成功。然而，对于工业上相关的多相金属纳米颗粒催化剂，使用这一策略来实现预测的多相不对称催化是一个长期的挑战，因为通过传统方法合成的纳米颗粒具有固有的多分散性。为了解决这一局限性，达斯教授和她的学生将开发原子精确的金属原子簇模型，其表面将具有新的手性配体来调节其催化活性，类似于均相不对称催化剂。他们的研究有助于确定与金属簇合物模型催化剂的不对称催化活性相关的关键参数，从而在未来更好地进行多相催化剂设计。这项研究与许多外联活动相结合，以吸引和鼓励代表不足的第一代或低收入学生攻读STEM学位和职业。这些措施包括在附近的高中和MSI组织研讨会和演示实验，以促进公众的科学和研究素养。此外，还将进行关于隐藏的隐性偏见和培养文化智力的培训，以创造一个包容和支持的实验室环境。达斯教授和她的学生将合成和表征一系列由新手性配体保护的原子精确的金属簇合物。通过单晶X射线结晶学、核磁共振、紫外可见光谱、荧光光谱、圆二色谱(CD)、电化学分析和质谱学等技术对这些簇合物的合成机理进行了研究。然后将这些合成准则应用于双金属手性金属簇合物，以研究协同作用对模型不对称转变的影响。最终，这项研究产生的设计规则可能会广泛应用于其他类别的非均相纳米材料，以了解和定制其原子精度的不对称催化性能。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.