Hydration and dynamics of l-glutamate ion in aqueous solution?

Physical Chemistry Chemical Physics Pub Date: 2020-12-15 DOI: 10.1039/D0CP05489E

Abstract

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.

Graphical abstract: Hydration and dynamics of l-glutamate ion in aqueous solution
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