Correlating Infrared and X-ray Absorption Energies for Molecular-Level Insight into Hydrogen Bond Making and Breaking in Solution

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• 作者：Mirabelle Pr茅mont-Schwarz ; Simon Schreck ; Marcella Iannuzzi ; Erik T. J. Nibbering ; Michael Odelius ; Philippe Wernet
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：June 25, 2015
• 年：2015
• 卷：119
• 期：25
• 页码：8115-8124
• 全文大小：465K
• ISSN：1520-5207

文摘

While ubiquitous, the making and breaking of hydrogen bonds in solution is notoriously difficult to study due to the associated complex changes of nuclear and electronic structures. With the aim to reduce the according uncertainty in correlating experimental observables and hydrogen-bond configurations, we combine the information from proximate methods to study the N鈥揌路路路O hydrogen bond in solution. We investigate hydrogen-bonding of the N鈥揌 group of N-methylaniline with oxygen from liquid DMSO and acetone with infrared spectra in the N鈥揌 stretching region and X-ray absorption spectra at the N K-edge. We experimentally observe blue shifts of the infrared stretching band and an X-ray absorption pre-edge peak when going from DMSO to acetone. With ab initio molecular dynamics simulations and calculated spectra, we qualitatively reproduce the experimental observables but we do not reach quantitative agreement with experiment. The infrared spectra support the notion of weakening the N鈥揌路路路O hydrogen bond from DMSO to acetone. However, we fail to theoretically reproduce the measured shift of the X-ray absorption pre-edge peak. We discuss possible shortcomings of the simulation models and spectrum calculations. Common features and distinct differences with the O鈥揌路路路O hydrogen bond are highlighted, and the implications for monitoring hydrogen-bond breaking in solution are discussed.