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Temperature and Pressure Effects on the Spin-lattice Relaxation Time of Hydrated Water Molecules by NMR

通过核磁共振研究温度和压力对水合水分子自旋晶格弛豫时间的影响

基本信息

批准号：
03640416
负责人：
TANIGUCHI Yoshihiro
金额：
$ 1.28万
依托单位：
RITSUMEIKAN University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

The temperature effects on the spine-lattice relaxation rates of hydrated D_2O molecules in the dilute solutions of alkali metal bromide (LiBr, NaBr, KBr, and CsBr) and tetraalkylammonium bromide (Me_4NBr, Et_4NBr, n-Pro_4NBr, and n-Bu_4NBr) salts have been studied by NMR spectroscopy, and the high pressure NMR polmer cell has been tested up to 500 bar at room temperature. The concentration dependences of D and ^<17>0 spine-lattice relaxation rates (R_1) of D_2O molecules in D_2O solutions of tetraalkylammonium bromide are repersented by the equation of R_1/R_Rﾟ= 1 + Bm + Cm^2 (R_1ﾟ ; pure D_2O, m ; mol kg^<-1>, B and C ; constants) at lower temperatures below 20 ﾟC. This means the overlap the hydration sphere of tetraalkylammonium ions, when the lower temperature induces the hydrogen bonded network structure of water. Analyzing these results on the model of the solvent-separated hydrophobic hydration, the rotationa motion of the solvent separated hydrophobic hydrated water molecules is faster than those of the hydrated water molecules. The concentration dependences of R_1 in D_2O molecules of alkali metal bromides are represented by the linear equation of R_1/R_1ﾟ = 1 + Bm in the wide range of temperatures of 5 ﾟC to 50 ﾟC. With increasing temperature, the B coefficients of salts solution increase from the negative to positive sign. Therefore, the rotational motion of hydrated water molecules of alkali metal ions is slower than that of the bulk water molecules.

用核磁共振波谱研究了碱金属溴化锂(LiBrr，NaBr.KBr.CsBr.)和四烷基溴化铵(Me4NBr，Et4NBr，n-Pro4NBr，n-Bu4NBr)稀溶液中温度对水合D_2O分子晶格驰豫速率的影响，并在室温下进行了高达500bar的高压核磁共振聚合室的测试.在20℃以下的较低温度下，D_2O分子在四烷基溴化铵的D_2O溶液中的主位-晶格驰豫速率(R_1)随温度的变化可用方程R_1/R_Rﾟ=1+Bm+Cm^2(R_1ﾟ；纯D_2O，m；ﾟ；-1&gt；，B和C；常数)来表示，这意味着当较低的温度诱导水的氢键网络结构时，四烷基铵离子的水化球面重叠。在溶剂分离疏水水化模型上分析这些结果，溶剂分离疏水水分子的旋转运动比水化水分子的旋转运动更快。碱金属溴化物D_2O分子中R_1的浓度依赖关系可用线性方程R_1/R_1ﾟ=1+Bm表示，在5ﾟC到50ﾟC的较宽温度范围内，盐溶液的B系数随温度的升高由负变正。因此，碱金属离子水合水分子的旋转运动慢于主体水分子的旋转运动。