Friesen Sergej, Fedotova Marina V, Kruchinin Sergey E, Buchner Richard
Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany.
G. A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Akademicheskaya St. 1, 153045 Ivanovo, Russian Federation.
Phys Chem Chem Phys. 2021 Jan 21;23(2):1590-1600. doi: 10.1039/d0cp05489e.
Aqueous solutions of sodium l-glutamate (NaGlu) in the concentration range 0 < c/M ≤ 1.90 at 25 °C were investigated by dielectric relaxation spectroscopy (DRS) and statistical mechanics (1D-RISM and 3D-RISM calculations) to study the hydration and dynamics of the l-glutamate (Glu-) anion. Although at c → 0 water molecules beyond the first hydration shell are dynamically affected, Glu- hydration is rather fragile and for c ⪆ 0.3 M apparently restricted to H2O molecules hydrogen bonding to the carboxylate groups. These hydrating dipoles are roughly parallel to the anion moment, leading to a significantly enhanced effective dipole moment of Glu-. However, l-glutamate dynamics is determined by the rotational diffusion of individual anions under hydrodynamic slip boundary conditions. Thus, the lifetime of the hydrate complexes, as well as of possibly formed [Na+Glu-]0 ionpairs and l-glutamate aggregates, cannot exceed the characteristic timescale for Glu- rotation.
在25℃下，通过介电弛豫光谱（DRS）和统计力学（1D-RISM和3D-RISM计算）研究了浓度范围为0 < c/M ≤ 1.90的l-谷氨酸钠（NaGlu）水溶液，以研究l-谷氨酸（Glu-）阴离子的水合作用和动力学。尽管在c → 0时，第一个水合壳层之外的水分子受到动力学影响，但Glu-水合作用相当脆弱，对于c ⪆ 0.3 M，显然仅限于与羧基形成氢键的H2O分子。这些水合偶极子大致与阴离子矩平行，导致Glu-的有效偶极矩显著增强。然而，l-谷氨酸动力学由单个阴离子在流体动力学滑移边界条件下的旋转扩散决定。因此，水合物络合物以及可能形成的[Na+Glu-]⁰离子对和l-谷氨酸聚集体的寿命不能超过Glu-旋转的特征时间尺度。
