Unfolding of Hydrated Alkyl Diammonium Cations Revealed by Cryogenic Ion Mobility-Mass Spectrometry

详细信息    查看全文

• 作者：Kelly A. Servage ; Kyle L. Fort ; Joshua A. Silveira ; Liuqing Shi ; David E. Clemmer ; David H. Russell
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：July 22, 2015
• 年：2015
• 卷：137
• 期：28
• 页码：8916-8919
• 全文大小：327K
• ISSN：1520-5126

文摘

Hydration of the ammonium ion plays a key role in determining the biomolecular structure as well as local structure of water in aqueous environments. Experimental data obtained by cryogenic ion mobility-mass spectrometry (cryo-IM-MS) show that dehydration of alkyl diammonium cations induces a distinct unfolding transition at a critical number of water molecules, n = 21 to 23, n = 24 to 26, and n = 27 to 29, for 1,7-diaminoheptane, 1,8-diaminooctane, and 1,10-diaminodecane, respectively. Results are also presented that reveal compelling evidence for unique structural transitions of hydrated ammonium ions associated with the development of the hydrogen-bond network around individual charged groups. The ability to track the evolution of structure upon stepwise dehydration provides direct insight into the intricate interplay between solvent鈥搈olecule interactions that are responsible for defining conformations. Such insights are potentially valuable in understanding how ammonium ion solvation influences conformation(s) of larger biomolecules.