Nature of hydration shells of a polyoxy‐anion with a large cationic centre: The case of iodate ion in water

Abstract

The structural nature of the solvation shells of an iodate ion, which is known to be a polyoxy-anion with a large cationic centre, is investigated by means of Born-Oppenheimer molecular dynamics (BOMD) simulations using BLYP and the dispersion corrected BLYP-D3 functionals. The iodate ion is found to have two distinct solvation regions around the positively charged iodine (iodine solvation shell or ISS) and the negatively charged oxygens (oxygen solvation shell or OSS). We have looked at the spatial, orientational, and hydrogen bond distributions of water in the two solvation regions. It is found that the water orientational profile in the ISS is typical of a cation hydration shell. The hydrogen bonded structure of water in the OSS is found to be very similar to that of the bulk water structure. Thus, the iodate ion essentially behaves like a positively charged iodine ion in water as if there is no anionic part. This explains why the cationic character of the iodate ion was prominently seen in earlier studies. The arrangement of water molecules in the two solvation shells and in the intervening regions around the iodate ion is further resolved by looking at structural cross-correlations. The electronic properties of the solvation shells are also looked at by calculating the solute-solvent orbital overlap and dipole moments of the solute and solvation shell water. We have also performed BOMD simulations of iodate ion-water clusters at experimentally relevant conditions. The simulation results are found to be in agreement with experimental results. © 2018 Wiley Periodicals, Inc.

Polyatomic Iodine Species at the Air–Water Interface and Its Relevance to Atmospheric Iodine Chemistry: An HD-VSFG and Raman-MCR Study

“…Such a preferred orientation of the polyatomic anion at interfacial region is expected to orient the interfacial water as H-down, as shown in Scheme b. MD simulation suggested that the water hydrating the “cation-like” iodine of IO 3 – orients their H atoms away from the iodine . Therefore, at interface, the water hydrating the iodine (of IO 3 – ) will be H-down oriented and also expected to contribute to the negative Imχ (2) signal around 3250 cm –1 .…”

Hydration Mimicry by Membrane Ion Channels

“…As with experiments, AIMD simulation results are challenged by demands of realistic access to suitable ranges of space and time (48). Nevertheless, recent developments in both algorithms and computer power have extended that ability, leading to improved information on ion hydration structures (49,50,51,52,53,54,55,56,57). Our presentation here highlights the correspondence between ion hydration structure illuminated by AIMD simulations with available experiment.…”

“Breaking” and “Making” of Water Structure at the Air/Water−Electrolyte (NaXO3; X = Cl, Br, I) Interface

“…However, in the case of IO 3 − , the relative intensity in the low-frequency region (below 3400 cm −1 ) is increased, pertaining to the strongly H-bonded water in the hydration shell of IO 3 − . 33,38 This has effectively led to increased spectral width as compared to that of bulk HOD (Figure 4c). These changes in the OHstretch spectrum of the hydration shell water, which are in accordance with the structure breaking (ClO 3 − and BrO 3 − ) and making (IO 3 − ) properties of the oxyhalide anions, are in good agreement with the Imχ (2) spectral changes at the corresponding air/water−NaXO 3 interfaces (Figures 2 and 3).…”