Molecular dynamics of carbohydrate aqueous solutions. Dielectric relaxation as a function of glucose and fructose concentration
Molecular dynamics of carbohydrate aqueous solutions. Dielectric relaxation as a function of glucose and fructose concentration
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DOI：
10.1021/jp0030084
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发表时间：
2001-03-15
影响因子：
3.3
通讯作者：
Kaatze, U
中科院分区：
文献类型：
--
作者：
Fuchs, K;Kaatze, U
在 1 至 5.4 momo 之间的某些溶质浓度 c 下，D-葡萄糖和 D-果糖水溶液的复数（电）介电常数已确定为 300 kHz 至 40 GHz 之间频率 v 的函数。 5.4 mol/L D-果糖溶液的介电常数谱是在 10 至 35 ℃ 之间的六个温度下测量的，其他谱是在 25 ℃ 下测量的。所有介电谱都显示出一个色散/介电损耗区域，这表明溶质和溶剂偶极矩的相当均匀的弛豫。从分析上讲，测量的光谱由科尔-科尔弛豫光谱函数表示，它对应于连续、对称的钟形弛豫时间分布。讨论光谱函数的参数以表明单糖表现出不寻常的水合特性。特别是，当按照偶极子重定向的等待和切换模型进行处理时，主要介电弛豫时间表明了糖类的异常水合行为。这表明这种行为反映了环分子的-OH基团拓扑与水结构的相容性。
At some solute concentrations c between 1 and 5.4 mom, the complex (electric) permittivity of aqueous solutions of D-glucose and D-fructose has been determined as a function of frequency v between 300 kHz and 40 GHz. The permittivity spectrum of the 5.4 mol/L D-fructose solution has been measured at six temperatures between 10 and 35 degreesC, and the other spectra have been taken at 25 degreesC. All dielectric spectra revealed one dispersion/dielectric loss region, which indicated a rather homogeneous relaxation of the solute and solvent dipole moments. Analytically, the measured spectra were represented by the Cole-Cole relaxation spectral function, which corresponds with a continuous, symmetrically bell shaped relaxation time distribution. The parameters of the spectral function are discussed to show that the monosaccharides exhibit unusual hydration properties. Particularly, when treated in terms of a wait-and-switch model of dipole reorientation, the principal dielectric relaxation time is indicative of the extraordinary hydration behavior of the saccharides. It is suggested that this behavior reflects the compatibility of the ring molecule's -OH group topology with the water structure.