Vibrational spectral studies of ion-ion and ion-solvent interactions. I. Zinc nitrate in water

Sze, Yu-Keung; Irish, D. E.

doi:10.1007/bf00646111

Cited by 46 publications

(43 citation statements)

References 28 publications

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“…ions to formation of ion pairs, we can note that, depending on the chemical nature of cations and the concentration, various types of associates and independently hydrated NO 3 ! ions can be present in aqueous solutions [22,24]. This is confirmed by the Raman spectra of 4.5 M aqueous solutions of zinc, cadmium(II), and mercury(II) nitrates [25,26].…”

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confidence: 59%

D-Structure of Aqueous Solutions of Cobalt(II) Nitrate at 298 and 323 K by X-Ray Diffraction

2005

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Aqueous solutions of cobalt(II) nitrate with 1 : 15, 1 : 25, and 1 : 40 mole ratios at 298 and 323 K were studied by the X-ray diffraction. As the solution concentration decreases, ion triads (1 : 15) pass into contact ion pairs (1 : 25) and then to independently hydrated ions (1 : 40). The structural variations are accompanied by increase in a number of water molecules in the second coordination sphere of the cations and in the hydration shell of the anions. Heating produces destruction of ion triads in the 1 : 15 solution and ion association in the 1 : 40 solution. The structure of all the solutions at 323 K is characterized by a system of contact ion pairs. The structure of concentrated aqueous solutions of electrolytes attracts considerable attention of researchers involved in the fundamental and applied science. Correlations of the trend in structure formation in aqueous electrolyte systems with the chemical nature of ions and solution concentration have been revealed [1]. Recently polythermal studies of such solutions have gained special importance [234]. To obtain statistical data on quantitative characteristics of aqueous electrolyte solutions and to extend the body of experimental information, in the present work we performed an X-ray diffraction study of aqueous solutions of cobalt(II) nitrate at various mole ratios and temperatures. The Co + ion is a complex-forming ion, and a series of X-ray researches have been devoted to its complex formation in solutions of cobalt(II) chlorides and bromides. The aim of the present work was to study structural aspects of ion hydration in solutions, and, therefore, we chose nitrate ions as counterions not inclined to complex formation.In early works [5, 6] on the basis of measuring viscosity of aqueous CoSO 4 solutions it was noted that Co 2+ ions reinforce water structure in a wide concentration range. Kinetic studies on oxygen exchange between nitrate ions and water molecules in aqueous solutions of Co(NO 3 ) 2 at concentrations close to the boundary of complete hydration revealed a twolayer hydrate surrounding [7,8]. In the crystal hydrates Co(NO 3 ) 2 . 2H 2 0 and Co(NO 3 ) 2 . 4H 2 0, cobalt ions are surrounded by six oxygen atoms at distances of 0.205130.2124 nm, of which two atoms belong to nitrate ions (0.206030.2097 nm) and the other two in the first case and four in the second, to water molecules [9]. The octahedral coordination of water molecules around the cation in concentrated aqueous solutions of cobalt(II) halides [10312] and sulfate [13] was revealed by X-ray diffraction analysis, the Co 2+ 3 OH 2 distances varying within 0.20730.216 nm. The formation of contact ion pairs by counterions in CoCl 2 solutions of various concentrations was established [11,14]. Aqueous solutions of CoCl 2 : nH 2 O (n = 6, 4, 2) at various temperatures (298, 313, 328, and 343) were studied by X-ray diffraction. In octahedral cobalt(II) complexes, the Co3O and Co3Cl distances were found to be 0.211 and 0.240 nm, respectively [15]. The number of Co3Cl contacts in saturated...

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confidence: 59%

D-Structure of Aqueous Solutions of Cobalt(II) Nitrate at 298 and 323 K by X-Ray Diffraction

2005

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“…For simplicity, the equilibria of aquo complexes with various geometry, [Zn(H 2 O) x ] 2+ will refer to either hexaaquo ( x = 6) or tetraaquo ( x = 4) complexes in this article. Vibrational spectroscopic investigations on aqueous solutions of zinc salts demonstrated formation of the tetraaquo complex at high salt concentrations where the water content decreases significantly [20]. The zinc pentaaquo-hydroxo complex also is in equilibrium with the octahedral and tetrahedral species.…”

Section: Zinc Speciationmentioning

confidence: 99%

The biological inorganic chemistry of zinc ions

Krężel

Maret

2016

Archives of Biochemistry and Biophysics

580

356

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The solution and complexation chemistry of zinc ions is the basis for zinc biology. In living organisms, zinc is redox-inert and has only one valence state: Zn(II). Its coordination environment in proteins is limited by oxygen, nitrogen, and sulfur donors from the side chains of a few amino acids. In an estimated 10% of all human proteins, zinc has a catalytic or structural function and remains bound during the lifetime of the protein. However, in other proteins zinc ions bind reversibly with dissociation and association rates commensurate with the requirements in regulation, transport, transfer, sensing, signalling, and storage. In contrast to the extensive knowledge about zinc proteins, the coordination chemistry of the “mobile” zinc ions in these processes, i.e. when not bound to proteins, is virtually unexplored and the mechanisms of ligand exchange are poorly understood. Knowledge of the biological inorganic chemistry of zinc ions is essential for understanding its cellular biology and for designing complexes that deliver zinc to proteins and chelating agents that remove zinc from proteins, for detecting zinc ion species by qualitative and quantitative analysis, and for proper planning and execution of experiments involving zinc ions and nanoparticles such as zinc oxide (ZnO). In most investigations, reference is made to zinc or Zn2+ without full appreciation of how biological zinc ions are buffered and how the d-block cation Zn2+ differs from s-block cations such as Ca2+ with regard to significantly higher affinity for ligands, preference for the donor atoms of ligands, and coordination dynamics. Zinc needs to be tightly controlled. The interaction with low molecular weight ligands such as water and inorganic and organic anions is highly relevant to its biology but in contrast to its coordination in proteins has not been discussed in the biochemical literature. From the discussion in this article, it is becoming evident that zinc ion speciation is important in zinc biochemistry and for biological recognition as a variety of low molecular weight zinc complexes have already been implicated in biological processes, e.g. with ATP, glutathione, citrate, ethylenediaminedisuccinic acid, nicotianamine, or bacillithiol.

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“…nonsymmetric octahedral or tetrahedral. A tetra hedral coordination has previously been taken into consideration for Zn species corresponding to (II) and (III) [8,9], Alternatively one may suppose that there is only one particular ionic composition resulting in polar entities which, however, might possibly develop subspecies distinguished by the involvement of solvent molecules (e.g. solvent shared contact and solvent sep arated ion pairs).…”

Section: Discussionmentioning

confidence: 99%

Dielectric Relaxation Spectroscopy of Electrolyte Solutions: ZnCl₂ in N-Methyl-2-pyrrolidone

Brockmann

Steffen

Stockhausen

1991

Zeitschrift Für Naturforschung A

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Vibrational spectral studies of ion-ion and ion-solvent interactions. I. Zinc nitrate in water

Cited by 46 publications

References 28 publications

D-Structure of Aqueous Solutions of Cobalt(II) Nitrate at 298 and 323 K by X-Ray Diffraction

D-Structure of Aqueous Solutions of Cobalt(II) Nitrate at 298 and 323 K by X-Ray Diffraction

The biological inorganic chemistry of zinc ions

Dielectric Relaxation Spectroscopy of Electrolyte Solutions: ZnCl₂ in N-Methyl-2-pyrrolidone

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Vibrational spectral studies of ion-ion and ion-solvent interactions. I. Zinc nitrate in water

Cited by 46 publications

References 28 publications

D-Structure of Aqueous Solutions of Cobalt(II) Nitrate at 298 and 323 K by X-Ray Diffraction

D-Structure of Aqueous Solutions of Cobalt(II) Nitrate at 298 and 323 K by X-Ray Diffraction

The biological inorganic chemistry of zinc ions

Dielectric Relaxation Spectroscopy of Electrolyte Solutions: ZnCl2 in N-Methyl-2-pyrrolidone

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Dielectric Relaxation Spectroscopy of Electrolyte Solutions: ZnCl₂ in N-Methyl-2-pyrrolidone