Department of Chemistry, University of Wisconsin─Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
J Phys Chem Lett. 2022 Mar 3;13(8):2046-2050. doi: 10.1021/acs.jpclett.1c02211.
This Viewpoint presents a re-examination of the conclusions of a study reported in (Saparbaev, . 2021, 12, 907) that compared the structure of microsolvated ions formed by electrospray ionization to those formed in the gas-phase a previously published cryogenic ion trap approach. We conducted additional experiments that clearly show that most of the observed differences in the IR spectra can be accounted for by considering the different spectroscopic action schemes used to obtain them. In particular, the presence of the D-tag induces shifts in some of the N-H and O-H peaks which need to be carefully considered before comparing spectra. Once these spectral effects are taken into account, we show that both clustering approaches yield similar cluster structures for the small GlyH(HO) species. Using unimolecular reaction rate theory, we also show that for the small complexes considered here, only the gas-phase equilibrium distribution of conformers should be expected in both experimental approaches. In addition, the barrier heights necessary to kinetically trap high-energy conformers at 298 K is explored using a series of model polyalanine chains.
这篇观点文章重新审视了 （Saparbaev， 。2021，12，907）中报道的一项研究的结论，该研究比较了电喷雾电离形成的微溶剂化离子与先前发表的低温离子阱方法在气相中形成的离子的结构。我们进行了额外的实验，这些实验清楚地表明，通过考虑用于获得它们的不同光谱作用方案，可以解释大部分观察到的红外光谱差异。特别是，D-tag 的存在会导致一些 N-H 和 O-H 峰的位移，在比较光谱之前需要仔细考虑这些位移。一旦考虑到这些光谱效应，我们表明，两种聚类方法对于小的 GlyH(HO) 物种都产生相似的簇结构。使用单分子反应速率理论，我们还表明，对于这里考虑的小复合物，在两种实验方法中都应该只预期气相平衡构象分布。此外，使用一系列模型丙氨酸链探索了在 298 K 下通过动力学捕获高能构象所需的势垒高度。
