Temperature dependence of structure and dynamics of the hydrated Ca<sup>2+</sup> ion according to <i>ab initio</i> quantum mechanical charge field and classical molecular dynamics

Lim, Len Herald V.; Pribil, Andreas B.; Ellmerer, Andreas E.; Randolf, Bernhard R.; Rode, Bernd M.

doi:10.1002/jcc.21405

Cited by 13 publications

(10 citation statements)

References 28 publications

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“…This rate of water exchange exceeds the rate extracted from ultrasonic absorption spectroscopy 4 by three orders of magnitude, but agrees with MD simulation results. 9 Our observations confirm that the exchange of a water molecule into and out of the first solvation shell occurs roughly five orders of magnitude faster for Ca 2+ than Mg 2+ . Despite the enormous difference in the residence times for water, the anion residence times vary surprisingly little between Ca 2+ and Mg 2+ .…”

Section: Discussionsupporting

confidence: 85%

“…Various experiments have been interpreted to be consistent with water residence times ranging from less than 150 ps 50 to roughly 100 ns, 4 and MD simulations have extracted residence times ranging from 15 ps to 150 ps. 9 Our measurements put a lower bound on the water-NCS -exchange of roughly 75 ps. In conjunction with the QENS results of Salmon et al, 50 we attribute a residence time for water of roughly 100 ps in the first solvation shell of Ca 2+ .…”

Section: Discussionmentioning

confidence: 99%

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Aqueous Mg²⁺and Ca²⁺Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy

Sun

Zhang

et al. 2013

J. Phys. Chem. B

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Biological systems must discriminate between calcium and magnesium for these ions to perform their distinct biological functions, but the mechanism for distinguishing aqueous ions has yet to be determined. Ionic recognition depends upon the rate and mechanism by which ligands enter and leave the first solvation shell surrounding these cations. We present a time-resolved vibrational spectroscopy study of these ligand exchange dynamics in aqueous solution. The sensitivity of the CN-stretch frequency of NCS(-) to ion pair formation has been utilized to investigate the mechanism and dynamics of ligand exchange into and out of the first solvation shell of aqueous magnesium and calcium ions with multidimensional vibrational (2DIR) spectroscopy. We have determined that anion exchange follows a dissociative mechanism for Mg(2+) and an associative mechanism for Ca(2+).

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Aqueous Mg²⁺and Ca²⁺Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy

Sun

Zhang

et al. 2013

J. Phys. Chem. B

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“…The 2DIR spectra for the CaBr 2 , CaI 2 , and Ca(ClO 4 ) 2 solutions shown in Figure B–D exhibit distinct spectra with intensity apparent in the (ω τ = 2068 cm –1 , ω m = 2093 cm –1 ) cross-peak region consistent with NCS – exchange from the free anion configuration to a CaNCS + CIP configuration. Unlike Mg 2+ , The slow rate of water-NCS – exchange cannot be corroborated with prior measurements because the residence times for water in the first solvation shell of Ca 2+ extracted from experiment , and molecular dynamics simulations range from 15 ps to roughly 100 ns.…”

Section: Resultsmentioning

confidence: 80%

“…consistent with NCS − exchange from the free anion configuration to a CaNCS + CIP configuration. Unlike Mg 2+ , The slow rate of water-NCS − exchange cannot be corroborated with prior measurements because the residence times for water in the first solvation shell of Ca 2+ extracted from experiment17,58 and molecular dynamics simulations59 range from 15 ps to roughly 100 ns. We have determined from these measurements that anion exchange in the first solvation shell surrounding Mg 2+ or Ca 2+ cations dominates the reaction dynamics on the tens of picoseconds time scale observed with 2DIR spectroscopy.…”

mentioning

confidence: 86%

Contact Ion Pair Formation between Hard Acids and Soft Bases in Aqueous Solutions Observed with 2DIR Spectroscopy

Sun

Zhang

et al. 2013

J. Phys. Chem. B

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The interaction of charged species in aqueous solution has important implications for chemical, biological, and environmental processes. We have used 2DIR spectroscopy to study the equilibrium dynamics of thiocyanate chemical exchange between free ion (NCS(-)) and contact ion pair configurations (MNCS(+)), where M(2+) = Mg(2+) or Ca(2+). Detailed studies of the influence of anion concentration and anion speciation show that the chemical exchange observed with the 2DIR measurements results from NCS(-) exchanging with other anion species in the first solvation shell surrounding Mg(2+) or Ca(2+). The presence of chemical exchange in the 2DIR spectra provides an indirect, but robust, determinant of contact ion pair formation. We observe preferential contact ion pair formation between soft Lewis base anions and hard Lewis acid cations. This observation cannot be easily reconciled with Pearson's acid-base concept or Collins' Law of Matching Water Affinities. The anions that form contact ion pairs also correspond to the ions with an affinity for water and protein surfaces, so similar physical and chemical properties may control these distinct phenomena.

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“…Indications for changes in the hydration shell of metal ions with rising temperature are demonstrated for instance in [52] and [53].…”

Section: Batch Sorption Experimentsmentioning

confidence: 97%

The influence of temperature and small organic ligands on the sorption of Eu(III) on Opalinus Clay

Schott¹,

Acker

Barkleit

et al. 2012

Radiochimica Acta

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The influence of temperature up to 50 • C and small organic ligands (citrate, tartrate) on the sorption of Eu(III) on the natural clay rock Opalinus Clay (OPA) under aerobic ( p CO 2 = 10 −3.5 atm) synthetic OPA pore water conditions (pH 7.6, I = 0.4 mol L −1 ) was investigated. Batch sorption experiments and time-resolved laser-induced fluorescence spectroscopy (TRLFS) were used to study these influencing factors on the Eu(III) sorption.Sorption isotherms and distribution coefficients R d (15 • C: log R d = 4.50 ± 0.05...50 • C: log R d = 5.54 ± 0.06) at 2 × 10 −9 mol L −1 Eu(III) as a function of the solid-to-liquid ratio (up to 3 g L −1 ) and temperature were determined. A significant temperature dependency of the Eu(III) sorption was observed. With rising temperature the Eu(III) sorption increases. The surface reaction is endothermic (∆H sorb ∼ 50 kJ mol −1 ). Using TRLFS, a surface species with a luminescence emission lifetime of 201 ± 9 µs was identified.In the presence of tartrate or citrate the Eu(III) sorption decreases with increasing ligand concentration due to a complex formation of Eu(III) in solution, with citrate having a more pronounced influence on the sorption than tartrate. With the batch sorption experiments it can be shown that at a citrate concentration larger than 10 −5 mol L −1 and at a tartrate concentration larger than 10 −4 mol L −1 an increasing Eu(III) desorption occurs. This result is supported by TRLFS measurements, which show the correlation between the complexation of Eu(III) by citrate or tartrate in solution and the Eu(III) desorption process. Possible Eu(III) citrate or Eu(III) tartrate surface species on OPA could not be detected using TRLFS.

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Temperature dependence of structure and dynamics of the hydrated Ca²⁺ ion according to ab initio quantum mechanical charge field and classical molecular dynamics

Cited by 13 publications

References 28 publications

Aqueous Mg²⁺and Ca²⁺Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy

Aqueous Mg²⁺and Ca²⁺Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy

Contact Ion Pair Formation between Hard Acids and Soft Bases in Aqueous Solutions Observed with 2DIR Spectroscopy

The influence of temperature and small organic ligands on the sorption of Eu(III) on Opalinus Clay

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Temperature dependence of structure and dynamics of the hydrated Ca2+ ion according to ab initio quantum mechanical charge field and classical molecular dynamics

Cited by 13 publications

References 28 publications

Aqueous Mg2+and Ca2+Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy

Aqueous Mg2+and Ca2+Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy

Contact Ion Pair Formation between Hard Acids and Soft Bases in Aqueous Solutions Observed with 2DIR Spectroscopy

The influence of temperature and small organic ligands on the sorption of Eu(III) on Opalinus Clay

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Temperature dependence of structure and dynamics of the hydrated Ca²⁺ ion according to ab initio quantum mechanical charge field and classical molecular dynamics

Aqueous Mg²⁺and Ca²⁺Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy

Aqueous Mg²⁺and Ca²⁺Ligand Exchange Mechanisms Identified with 2DIR Spectroscopy