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.

在下一个授权期，我们研究的总体目标将是扩大对在气相离子经常表现出的新的成键环境中发现的分子间和分子内相互作用的本质的理解，并探索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，我们将采用实验研究和计算研究相结合的四管齐下的方法。使用的第一种实验方法是高压质谱仪(HPMS)，它允许研究作为温度函数的气相离子-分子反应和平衡。通过这种方式，可以获得这些过程的准确的Ho和So的实验值，从而对所涉及的势能景观进行准确的、定量的理解。第二种实验方法涉及傅里叶变换离子回旋共振光谱仪(FTICR)，它允许在低压下将离子限制在电磁陷阱中很长一段时间。第三项被开发的技术是利用自由电子激光(FEL)的红外多光子解离(IRMPD)实验。最后，我们的所有实验工作都伴随着使用电子结构方法的计算研究，这对理解成键和能量学以及解释振动光谱都有很大帮助。随附的RTI应用程序还建议在我们的实验室增加一个OPO激光系统，以允许在滑铁卢进行IRMPD实验。 将要进行的原则性实验有几种不同的类型。我们最近通过FTICR实验展示了从气相双分子H/D反应中可以获得对生物小分子结构和动力学的重要见解。例如，Na+(Ala)n系列盐化聚丙氨酸(n=2-14)在H/D交换动力学的数目和速度上表现出惊人的一致性，尽管随着氨基酸残基的增加，聚丙氨酸的结构发生了显著的变化。质子化谷胱甘肽及其质子化二聚体的H/D交换实验目前也在进行中。另一个研究领域涉及一些新的气相团簇的形成和表征。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，类似于在气相中形成盐晶体的能力。此外，研究还发现，随着团簇尺寸的增大，氯化胍形成非常大的团簇，呈现出更大范围的碗状和球状形状。最后，由于全顺六氟环己烷和相关取代环己烷的离子加合物表现出极强的离子结合作用，一种新型的体系正在被研究中。红外光谱分析有助于它们的表征。