化学学报 ›› 2011, Vol. 69 ›› Issue (11): 1273-1279.    下一篇

研究论文

水合甘氨酸体系水桥式质子迁移的理论研究

孟祥军   

  1. 唐山师范学院化学系 唐山 063000
  • 收稿日期:2010-12-07 修回日期:2010-12-26 出版日期:2011-06-14 发布日期:2011-01-18
  • 通讯作者: 孟祥军 E-mail:xjmeng_1974@126.com
  • 基金资助:

    河北省教育厅发展基金;唐山市应用基础基金;唐山师范学院基金

Theoretical Studies on the Proton Transfer through Water Bridges in Hydrated Glycine Cluster

MENG Xiang-Jun   

  1. (Department of Chemistry, Tangshan Teacher s College, Tangshan 063000)
  • Received:2010-12-07 Revised:2010-12-26 Online:2011-06-14 Published:2011-01-18
  • Contact: MENG Xiang-Jun E-mail:xjmeng_1974@126.com

水分子与甘氨酸作用会导致甘氨酸羧基上的质子迁移到氨基上,质子可以通过水分子链进行迁移。采用密度泛函理论的B3LYP/6-31++g**方法研究了水分子链的逐渐增长(1~5个水分子)对质子迁移的影响,发现水分子数少于5时,质子迁移一步完成;水分子数为5时,质子迁移经由一个中间体,需两步完成;水分子链的增长使质子迁移反应的自由能越来越低,但是反应的活化能越来越高,即在热力学上有利于质子迁移反应,在动力学上不利于质子迁移反应。

关键词: 水合甘氨酸, 质子迁移, 两性离子, 水桥链, 密度泛函理论

Density function theory (DFT) at the level of B3LYP/6-31++g** was employed to theoretically investigate the intramolecular proton transfer through water bridge chain from carboxyl to amino in glycine cluster. The number of water molecules plays an important role in the proton transfer through water bridge chain. When the number of water molecules in water bridge chain is less than 5, the proton transfer through water bridge chain will complete cooperatively in one step, otherwise the proton transfer will complete in two steps via an intermediate. With the increase of water molecule chain increasing the activation energy but reducing the free energy of the reaction, so, the increase of water molecule chain is not in favor of the proton transfer dynamically, but is in favor of proton transfer thermally.

Key words: hydrated glycine, proton transfer, zwitterions, water bridge chain, DFT

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