The opposite effects of sodium and potassium cations on water dynamics

Abstract

Water rotational dynamics in NaSCN and KSCN solutions at a series of concentrations are investigated using femtosecond infrared spectroscopy and theory.

Molecular mechanism of water reorientational slowing down in concentrated ionic solutions

“…Additionally, advanced polarizable force field models are often unavailable for many commonly studied ions. Since the ion-water interaction models used herein nicely reproduce the clustering characters measured by the coherent 2D infrared techniques for various electrolytes at a series of concentrations (6,18,22,23), it provides a cost-effective means to describe the clustering phenomenon to the extent needed for our discussion.…”

“…It is difficult to understand the aforementioned retardation in the ideal solution picture. In fact, in less concentrated (i.e., closer to ideal) solutions, water frame rotation can become faster for some electrolytes and slows down for others (6). On the other hand, collective water motion around the large biomolecules is always retarded comparing to that in pure water (3,4).…”

“…ion specificity | water rotation | ionic solution | femtosecond infrared | structure dynamics T he dynamics of water molecules surrounding hydrated ions and ionic moieties plays an important role in a broad range of chemical and biological phenomena (1)(2)(3)(4)(5)(6). In protein solutions, for example, amino acids with charged side chains strongly affect the water motion in their vicinity, which consequently impacts various protein biological processes such as enzyme catalysis and folding (3)(4)(5).…”

Picosecond orientational dynamics of water in living cells

“…The rotation of such rapidly reorienting water molecules can be tracked in real time using ultrafast time-resolved infrared spectroscopy, which directly probes the random orientational motion of the water–OH bonds (or OD bonds in the case of deuterated water). This method has been used previously to investigate water dynamics in neat water 41 – 45 , and aqueous solutions of salts 46 – 49 and biomolecules 20 , 21 , 50 – 52 . Alternatively, the collective orientational motion of the dipole moments of water molecules can be probed by measuring the electric-field induced polarization of a sample as function of field frequency using dielectric-relaxation spectroscopy (DRS) 53 , 54 .…”

K0.36(H2O)yWS2: a new layered compound for reversible hydrated potassium ion intercalation in aqueous electrolyte

“…8 Moreover, the Stokes radius (total radius of ion and bound water molecules) of hydrated K + is smaller than that of hydrated Li + or Na + , which can facilitate K + transport in aqueous electrolytes. 9 However, because the stable electrochemical window of conventional aqueous system (1.23 V) is much narrower than non-aqueous systems, the selection of electrode materials for aqueous batteries is challenging. Only materials with operating potential located between the H 2 and O 2 evolution potential are appropriate and they should be chemically stable in H 2 O during the charge/discharge process.…”