Hydrogen Bonding between Water and Tetrahydrofuran Relevant to Clathrate Formation

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• 作者：Mary Jane Shultz ; Tuan Hoang Vu
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：July 23, 2015
• 年：2015
• 卷：119
• 期：29
• 页码：9167-9172
• 全文大小：297K
• ISSN：1520-5207

文摘

Tetrahydrofuran (THF) is well-known as a clathrate former as well as a promoter for gas hydrate formation. This work examines interactions between water and tetrahydrofuran via the effect on water鈥檚 vibrational spectrum. Due to water鈥檚 large oscillator strength in the hydrogen-bonded region, interactions are diagnosed by isolating small clusters in a transparent medium (carbon tetrachloride in this study). A weak THF/water hydrogen bond is reflected by a 3450 cm^鈥? OH-donor vibration (blue shifted from the water/water hydrogen bond) and a 3685 cm^鈥? nonbonded OH stretch (blue shifted 22 cm^鈥? from the decoupled OH stretch in this medium). Increasing the THF concentration results in another 20 cm^鈥? blue shift of the OH-donor stretch. Additional THF does not complex with free water but rather joins with existing THF/water structures to form a cluster enriched in THF. These results complement previous work examining THF vibrations in clathrate hydrates. Together, they generate a picture in which water mediates between THF pairs 鈥?mediation that affects vibrational frequencies of both species. In addition to a frequency shift, water鈥檚 hydrogen-bonded resonance gains oscillator strength due to its mediating configuration.