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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=689370
• 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.*****

我们的研究在下一个补助金期间的总体目标将是扩大的理解，发现在新的键合环境中的分子间和分子内的相互作用经常显示气相离子和探测气相离子的单分子和双分子反应动力学的性质。为了解决这些目标，我们将使用一个四管齐下的方法结合实验和计算研究。第一种实验方法是高压质谱法（HPMS），它允许研究气相离子分子反应和平衡作为温度的函数。通过这种方式，可以获得这些过程的Ho和So的准确实验值，从而对所涉及的势能景观进行准确，定量的了解。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限制在电磁阱中很长一段时间。第三种技术是红外多光子解离（IRMPD）实验，涉及自由电子激光（FEL）。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，这大大有助于理解键合和能量学以及振动光谱的解释。RTI的一项附带申请还建议在我们的实验室增加一个OPO激光系统，以便在滑铁卢进行IRMPD实验。要进行的原理实验有几种不同的类型。最近，我们已经证明了显着的洞察小生物分子的结构和动力学，可以从气相双分子H/D反应使用FTICR实验。作为一个例子，已经发现Na+（Ala）n系列钠化聚丙氨酸（n = 2-14）在H/D交换动力学的数量和速度方面表现出惊人的一致性，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著变化。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的烷基氯化铵，这表明在气相中形成类似于盐晶体形成的扩展网络的能力。 此外，发现氯化胍形成非常大的簇，其随着簇尺寸的增加而呈现逐渐更大程度的碗状和球状形状。最后，一种新型的系统，涉及离子加合物的全顺式六氟环己烷和相关的取代环己烷正在调查中，因为它们表现出非常强的离子结合相互作用。IRMPD光谱有助于其表征。*