Structure, Energetics, Reaction Dynamics and Vibrational Spectra of Gaseous Ions

气态离子的结构、能量学、反应动力学和振动谱

• 批准号: RGPIN-2016-04142
• 负责人: McMahon, Terrance
• 金额: $ 3.35万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709005
• 关键词: Structure; Energetics; Reaction; Dynamics; Vibrational

The general objectives of our research over the next grant period will be to expand the understanding of the nature of inter- and intra-molecular interactions found in the novel bonding environments frequently displayed by gas phase ions and to probe both the unimolecular and bimolecular reaction dynamics of gas phase ions. In order to address these objectives we will use a four-pronged approach combining both experimental and computational studies. The first of the experimental methods used is High Pressure Mass Spectrometry (HPMS), which permits the study of gas-phase ion-molecule reactions and equilibria as a function of temperature. In this way, accurate experimental values of Ho and So can be obtained for these processes leading to an accurate, quantitative understanding of the potential energy landscapes involved. The second experimental approach involves Fourier Transform Ion Cyclotron Resonance Spectrometry (FTICR) which permits confinement of ions in an electromagnetic trap for extremely long periods of time at low pressures. The third technique exploited is Infrared Multiple Photon Dissociation (IRMPD) experiments involving a Free Electron Laser (FEL). Finally, all of our experimental work is accompanied by computational studies using electronic structure methods which greatly aid in the understanding of bonding and energetics as well as in the interpretation of vibrational spectra. An accompanying RTI application also proposes to add an OPO laser system to our laboratory to permit IRMPD experiments to be carried out at Waterloo. The principle experiments to be carried out are of several different types. We have demonstrated recently the significant insight into small biomolecule structure and dynamics that can be gained from gas phase bimolecular H/D reactions using FTICR experiments. As an example, the Na+(Ala)n series of sodiated polyalanines (n = 2-14) have been found to exhibit a surprising consistency in the number and speed of H/D exchange dynamics despite significant changes in the structures of the polyalanines as the number of amino acid residues increases. H/D exchange experiments are also currently in progress for protonated glutathione and its protonated dimer. Another area of study involves the formation and characterization of some novel gas phase clusters. We are investigating a series of alkylammonium chlorides which show the capability of forming extended networks resembling the formation of salt crystals in the gas phase. In addition, guanidinium chloride is found to form very large clusters which take on progressively greater extents of bowl and ball like shapes as the cluster size increases. Finally, a new type of systems involving ionic adducts of all-cis hexafluorocyclohexane and related substituted cyclohexanes are under investigation as they exhibit extremely strong ion binding interactions. IRMPD spectra aid in their characterization.

我们在下一个资助期内研究的总体目标将是扩大对气相离子经常表现出的新型键合环境中分子间和分子内相互作用本质的理解，并探讨气相离子的单分子和双分子反应动力学。为了实现这些目标，我们将采用四管齐下的方法，结合实验和计算研究。第一种使用的实验方法是高压质谱 (HPMS)，它可以研究气相离子分子反应和平衡随温度的变化。通过这种方式，可以获得这些过程的 Ho 和 So 的准确实验值，从而准确、定量地了解所涉及的势能景观。第二种实验方法涉及傅里叶变换离子回旋共振光谱法 (FTICR)，它允许在低压下将离子长时间限制在电磁阱中。第三种技术是涉及自由电子激光器 (FEL) 的红外多光子解离 (IRMPD) 实验。最后，我们所有的实验工作都伴随着使用电子结构方法的计算研究，这极大地有助于理解键合和能量学以及振动光谱的解释。随附的 RTI 申请还建议在我们的实验室添加 OPO 激光系统，以便能够在滑铁卢进行 IMPD 实验。 要进行的原理实验有几种不同的类型。最近，我们展示了使用 FTICR 实验从气相双分子 H/D 反应中获得的对小生物分子结构和动力学的重要见解。例如，Na+(Ala)n 系列钠化聚丙氨酸 (n = 2-14) 被发现在 H/D 交换动力学的数量和速度方面表现出令人惊讶的一致性，尽管随着氨基酸残基数量的增加，聚丙氨酸的结构发生了显着变化。目前质子化谷胱甘肽及其质子化二聚体的 H/D 交换实验也在进行中。另一个研究领域涉及一些新型气相簇的形成和表征。我们正在研究一系列烷基氯化铵，它们显示出形成扩展网络的能力，类似于气相中盐晶体的形成。 此外，发现氯化胍形成非常大的簇，随着簇尺寸的增加，其逐渐呈现更大程度的碗状和球状形状。最后，一种涉及全顺式六氟环己烷和相关取代环己烷离子加合物的新型系统正在研究中，因为它们表现出极强的离子结合相互作用。 IRMPD 光谱有助于对其进行表征。