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Structural characterization of organometallic reaction intermediates and vibrational mechanics of water cages with temperature-controlled cryogenic ion spectroscopy

有机金属反应中间体的结构表征和水笼振动力学的温控低温离子光谱

基本信息

批准号：
1465100
负责人：
Mark Johnson
金额：
$ 52万
依托单位：
Yale University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-01 至 2019-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1465100&HistoricalAwards=false
关键词：
Structural characterization organometallic reaction intermediates

项目摘要

With this award, the Chemical Structure, Dynamics and Mechanisms program is supporting fundamental research of Professor Mark A. Johnson at Yale University. Johnson is developing a new type of scientific instrument that yields precise structural information on complex molecular architectures extracted from solution. Under this grant, he will expand the scope of the method to enable the capture and structural characterization of key reaction intermediates that underlie the mechanisms of small molecule (e.g., alkenes, H2O, H2) activation by contemporary homogeneous organometallic catalysts. The motivation to identify these transient species is that, at present, much of the effort in catalyst design involves extensive trial and error based on overall yield, while little is often known about exactly what aspects of the chemical transformation are being affected by the various modifications. Students and visiting faculty involved in this endeavor integrate elements of bioanalytical chemistry with atomic, molecular and optical (AMO) physics to create a new platform for chemical analysis. As such, this program directly interfaces physical chemistry students with immediate challenges addressed by synthetic colleagues, and consequently prepares a new generation of scientists with a versatile skill set, well centered in the chemical sciences. An ongoing and extensive collaboration with theoretical colleague Prof. Anne McCoy at Ohio State further broadens the impact of the work by creating an interactive venue for young theorists to sharpen their skills on emergent scientific themes. Graduate students and postdocs directly involved in the project also work in close collaborations with laboratories in Germany. This also contributes to their preparedness to perform at an increasingly competitive international level in the elite arena of basic science. Closer to home, this program integrates faculty from undergraduate institutions through summer research opportunities, and students from nearby universities without graduate programs are incorporated into ongoing work by carrying out senior research projects at Yale. Finally, this program has a longstanding tradition of opening its doors to students in the New Haven schools to illustrate how the basic science principles they are learning are in play at the foundation of the new methods under development. Cryogenic Ion Vibrational Predissociation Spectroscopy (CVIP) is a new instrumental technique which integrates mass spectrometry with high resolution infrared spectroscopy. One key feature of the approach is the implementation of cryogenic processing of the gas phase ions to effectively quench the reactive species into well-defined structures that yield sufficiently sharp features in their vibrational spectra to allow structure determination. This is carried out using vibrational predissociation spectroscopy of very weakly bound adducts attached to target ions in a custom built, radio frequency ion trap held at 5K. In addition to its application to catalysis, the proposed work also addresses key unanswered questions regarding the critical local interactions that underlie bulk behavior of pure water as well as the layer of water molecules in direct contact with charged solutes. Because the microscopic behavior of water is central to so many fields of science, this aspect of the work is ongoing, and has impacted efforts ranging from the mechanism of vision to the remediation of heavy metals in contaminated environments.

有了这个奖项，化学结构，动力学和机制计划是支持马克教授的基础研究。耶鲁大学的约翰逊。约翰逊正在开发一种新型的科学仪器，可以从溶液中提取复杂分子结构的精确结构信息。根据这项资助，他将扩大该方法的范围，以实现对小分子机制（例如，烯烃、H2O、H2）活化。识别这些瞬时物种的动机是，目前，催化剂设计中的大部分努力涉及基于总产率的广泛试验和错误，而对于化学转化的哪些方面受到各种修饰的影响通常知之甚少。参与这项奋进的学生和客座教师将生物分析化学的元素与原子，分子和光学（AMO）物理学相结合，为化学分析创造了一个新的平台。因此，该计划直接将物理化学学生与合成同事所面临的直接挑战相结合，从而为新一代科学家提供了以化学科学为中心的多功能技能。与俄亥俄州的理论同事安妮麦考伊教授进行了持续和广泛的合作，通过为年轻的理论家创造一个互动的场所来提高他们在新兴科学主题上的技能，进一步扩大了工作的影响。直接参与该项目的研究生和博士后也与德国的实验室密切合作。这也有助于他们做好准备，在基础科学的精英竞技场上在竞争日益激烈的国际水平上发挥作用。在离家更近的地方，该计划通过夏季研究机会整合了本科院校的教师，而附近大学没有研究生课程的学生则通过在耶鲁大学开展高级研究项目来融入正在进行的工作。最后，该计划有一个长期的传统，即向纽黑文学校的学生敞开大门，以说明他们正在学习的基本科学原理如何在开发中的新方法的基础上发挥作用。低温离子振动预解离光谱（CVIP）是一种将质谱和高分辨红外光谱相结合的新仪器技术。该方法的一个关键特征是实施气相离子的低温处理，以有效地将反应性物质淬灭成在其振动光谱中产生足够尖锐的特征以允许结构确定的明确定义的结构。这是使用振动预解离光谱的非常弱的结合加合物附着在一个定制的目标离子，射频离子阱保持在5K。除了其在催化方面的应用外，这项研究还解决了关键的未回答的问题，即纯水的本体行为以及与带电溶质直接接触的水分子层的关键局部相互作用。由于水的微观行为是许多科学领域的核心，因此这方面的工作正在进行中，并影响了从视觉机制到受污染环境中重金属修复等工作。