Negligible Isotopic Effect on Dissociation of Hydrogen Bonds

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• 作者：Chuanqi Ge ; Yuneng Shen ; Gang-Hua Deng ; Yuhuan Tian ; Dongqi Yu ; Xueming Yang ; Kaijun Yuan ; Junrong Zheng
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：March 31, 2016
• 年：2016
• 卷：120
• 期：12
• 页码：3187-3195
• 全文大小：481K
• ISSN：1520-5207

文摘

Isotopic effects on the formation and dissociation kinetics of hydrogen bonds are studied in real time with ultrafast chemical exchange spectroscopy. The dissociation time of hydrogen bond between phenol-OH and p-xylene (or mesitylene) is found to be identical to that between phenol-OD and p-xylene (or mesitylene) in the same solvents. The experimental results demonstrate that the isotope substitution (D for H) has negligible effects on the hydrogen bond kinetics. DFT calculations show that the isotope substitution does not significantly change the frequencies of vibrational modes that may be along the hydrogen bond formation and dissociation coordinate. The zero point energy differences of these modes between hydrogen bonds with OH and OD are too small to affect the activation energy of the hydrogen bond dissociation in a detectible way at room temperature.