Thermochemistry of Metal-Ligand Bonds and the Dynamics of Collision-Induced Dissociation

本项目利用流动管离子产生和导引离子束串联质谱仪(GIBMS)相结合的技术，在化学动力学和气相金属有机离子化学领域进行持续研究。用这个装置，将产生热化的原子离子和多原子离子。通过准确测量在热能和超热能下的绝对反应几率，将获得关于单一质量选择物种的详细的动力学和热力学数据。将开发两个新的实验设施：1)一个电喷雾离子(ESI)源，它应该能够在气相中更常规地产生不挥发的和热脆弱的离子，并提供更容易获得多电荷物种的途径。2)利用“电子状态层析”研究较重过渡元素特定状态化学的来源。将研究一系列化学体系，并将重点放在三个相关领域：1)碰撞诱导解离的动力学；2)较重的第三排过渡金属的化学；以及3)金属离子与生物相关分子的结合。所有这三个领域都隐含着扩大实验所需的理论计算。这项计划的一个动机是，显然有兴趣在气相离子研究中获得的详细信息与凝聚态有机金属化学、均相催化和生物系统的“真实世界”之间建立更好的相关性。我们有意识地选择研究复杂程度不断提高的简单体系，以便定量评估金属化学的趋势。通过全面研究许多金属和许多配体的热化学，热力学数据中的趋势(周期性、随配体数量的变化、电子态的变化)使我们能够超越获得数据的气相场所。学生和博士后研究员将参与这项研究。作为化学试剂，金属是生物系统的重要组成部分，作为酶的活性部位，有助于调节细胞功能和控制结构。在技术上，金属被广泛用作催化剂，以生产各种重要的精细化学品和燃料。此外，专门设计用于与某些金属选择性相互作用的分子是清理和净化核废料所必需的。本项目的研究旨在提供有关金属与与生物系统和化学工业有关的化学成分相互作用强度的基本信息。这最容易通过检查复杂程度不断提高的模型系统来实现。这使得能够对这一信息中的趋势进行定量评估，从而能够开发对更复杂的化学环境的预测能力。在这项工作中，被称为导引离子束串联质谱仪的专门设备被用来检查金属离子与各种化学物种的相互作用。这可以在单分子上完成，这样就可以消除来自环境的干扰作用。这使得研究可以专注于阐明控制相互作用的特定因素。与理论的密切合作提供了更多的洞察力并提供了基本的预测能力。这项研究将与学生和博士后研究助理一起进行，他们因此接受准备深造或进入科学/技术工作队伍的培训。

AbstractProposal: CHE-0135517PI: Armentrout, Peter B.This project consists of continuing research in the fields of chemical dynamics and gas-phase organometallic ion chemistry using a combined techniques of flow tube ion production and guided ion beam tandem mass spectrometry (GIBMS). With this apparatus, thermalized atomic and polyatomic ions will be produced. Detailed kinetic and thermodynamic data on single mass-selected species will be obtained by accurately measuring the absolute reaction probabilities at thermal and hyperthermal energies. Two new experimental facilities will be developed: 1) An electrospray ion (ESI) source that should enable more routine generation of nonvolatile and thermally fragile ions in the gas phase and provide easier access to multiply charged species. 2) A source to study state-specific chemistry of heavier transition elements that utilizes "electronic state chromatography". A range of chemical systems will be studied and will emphasize three related areas: 1) the dynamics of collision-induced dissociation; 2) the chemistry of the heavier third-row transition metals; and 3) metal ion binding to biologically relevant molecules. Implicit in all three areas will be theoretical calculations needed to augment the experiments. One motivation for this program is the obvious interest in making better correlations between the detailed information available from gas-phase ion studies with the "real world" of condensed-phase organometallic chemistry, homogeneous catalysis, and biological systems. We make the conscious choice to study simple systems that progress in complexity in order to quantitatively assess trends in metal chemistry. By comprehensively studying the thermochemistry of many metals and many ligands, the trends (periodic, changes with number of ligands, variations in electronic states) in the thermodynamic data allow us to transcend the gas-phase venue where the data are obtained. Students and post doctoral research associates will participate in this research.As chemical reagents, metals are important components of biological systems, acting as active sites in enzymes and helping to regulate cell function and to control structure. Technologically, metals are used extensively as catalysts to produce a wide range of important fine chemicals and fuels. In addition, molecules specifically designed to interact selectively with certain metals are needed for nuclear waste cleanup and decontamination. The research done in this project is designed to provide fundamental information about the strength of the interactions of metals with chemical components relevant to biological systems and the chemical industry. This is most readily accomplished by examining model systems that progress in complexity. This permits the trends in this information to be quantitatively assessed, which allows the development of predictive capabilities for more complex chemical environments. In this work, specialized devices known as guided ion beam tandem mass spectrometers are utilized to examine metal ion interactions with a variety of chemical species. This can be accomplished on single molecules such that interfering interactions from the environment can be eliminated. This allows the study to focus on elucidating the specific factors that control the interaction. A close collaboration with theory provides additional insight and provides essential predictive capabilities. The research will be done with students and post doctoral research associates who thereby receive training in preparation for advanced studies or entering the scientific/technical workforce.