Collaborative Research: Enantioselectivity in Heterogeneous Catalysts via the Addition of Chiral Modifiers

生物分子的结构单元可以表现出右手对称性或左手对称性;这种结构单元被称为对映体。 在生物体中发现的所有生物分子都只有一种“手性”，即分子只以一种对映体形式存在。此外，同一分子的不同对映体可以以完全不同的方式与生物体相互作用，有时是有益的，有时是灾难性的。 由于错误的手性会造成伤害，因此药物和农用化学品必须以对映体纯的形式合成。这种合成可以在药物合成后通过纯化来完成，但这种方法通常是困难和麻烦的。 最好是开发其中仅制备药物的一种对映异构体的方法。对映体纯合成可以通过使用固相催化剂来实现，所述固相催化剂具有被特异性改性以优先产生仅具有单手性的分子的表面。已经有一些试错的努力来发现这种多相催化剂，但迄今为止成功有限。Tysoe博士（威斯康星大学密尔沃基分校）和Zaera博士（加利福尼亚大学河滨分校）在研究理想条件下催化体系的表面化学方面具有丰富的经验。 他们的研究项目侧重于了解在更复杂和现实的系统中控制对映体选择性的分子相互作用，用于先进的药物制造。Tysoe和Zaera坚定地致力于教育妇女和少数民族，特别是在实验室和通过正式课程的西班牙裔学生。 他们参加了密尔沃基和滨江的外展计划，并将与该项目相关的研究纳入这些活动。 在化学部化学催化计划的资助下，Tysoe和Zaera博士正在研究由辛可尼丁类似物1-（1-萘基）乙胺（NEA）修饰的模型钯（111）和铂（111）手性催化剂的表面化学，使用扫描隧道显微镜（STM），红外吸收光谱，反应性测量和第一原理密度泛函理论（DFT）计算。这项研究提供了一些前手性反应物和NEA之间的非对映体相互作用的分子水平的理解，以及控制它们的力量。他们正在研究是否从单晶研究中的手性表面化学的详细分子的理解是相关的现实条件下发生的反应途径，即在大气压下，在液相的存在下。由此产生的理解可以提供如何提高催化选择性的见解。 该研究有助于有针对性地设计负载型多相不对称催化剂。预计这种能力将对制药和农业化学工业产生重大的经济影响。Tysoe博士和Zaera博士专注于通过他们的研究和外展计划教育妇女和少数民族，这是该项目更广泛影响的一部分。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Biomolecular building blocks can exhibit either right- or left-handed symmetries; such building blocks are known as enantiomers. All biomolecules found in living organisms have only one "handedness', that is, the molecules exist only in one enantiomeric form. Moreover, different enantiomers of the same molecule can interact with living organisms in completely different ways, sometimes beneficially and sometimes with catastrophic effects. As the wrong handedness can cause harm, pharmaceuticals and agrochemicals must be synthesized in enantiopure forms. This synthesis may be accomplished by purification after the drug has been synthesized, but that approach is often difficult and cumbersome. It is preferable to develop processes in which only one enantiomer of the drug is made. Enantiopure syntheses can be accomplished by using solid-phase catalysts with surfaces that are specifically modified to preferentially produce molecules with only one handedness. There have been a number of trial-and-error efforts to discover such heterogeneous catalysts, but success has so far been limited. Drs. Tysoe (University of Wisconsin-Milwaukee) and Zaera (University of California-Riverside) have considerable experience in studying the surface chemistry of catalytic systems under ideal conditions. Their research project focuses on understanding the molecular interactions that control enantio-selectivity in more complex and realistic systems for the advanced manufacturing of pharmaceuticals. Drs. Tysoe and Zaera are strongly committed to educating women and minorities, in particular, Hispanic students both in the laboratory and through formal courses. They participate in outreach programs at Milwaukee and Riverside, and are incorporating the research associated with this project into those activities. With funding from the Chemical Catalysis Program of the Chemistry Division, Drs. Tysoe and Zaera are studying the surface chemistry of model palladium(111) and platinum(111) chiral catalysts modified by a cinchonidine analog, 1-(1-naphthyl) ethylamine (NEA), using scanning tunneling microscopy (STM), infrared absorption spectroscopy, reactivity measurements, and first-principles density functional theory (DFT) calculations. This research provides a molecular-level understanding of the diastereomeric interactions between a number of prochiral reactants and NEA, and the forces that control them. They are investigating whether the detailed molecular understanding of the chiral surface chemistry from single-crystal studies in ultrahigh vacuum is relevant to the reaction pathways occurring under realistic conditions, that is, under atmospheric pressures and in the presence of a liquid phase. The resulting understanding may provide insights into how to improve catalytic selectivity. The research may facilitate the targeted design of supported heterogeneous enantioselective catalysts. Such an ability is expected to have a significant economic impact in the pharmaceutical and agrochemical industries. Drs. Tysoe and Zaera focus on educating women and minorities through their research and outreach programs as part of the broader impacts of the project.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.