Specific Salt Effect on the Solubility of <i>fac</i>-Tris(<i>α</i>-amino acidato)cobalt(III)

Yoshimura, Yukio

doi:10.1246/bcsj.69.2565

Cited by 6 publications

(3 citation statements)

References 15 publications

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“…S2 in ESIw) are in agreement with its C 3 symmetry structure. Although the sparingly soluble complex 2 was known since decades, 38 detailed investigation of salts effects 51 on its solubility by NMR techniques was not possible. In contrast, the dinuclear complex 1 is well suited for this kind of experiments due to its high solubility.…”

Section: Circular Dichroismmentioning

confidence: 99%

Synthesis, structure, circular dichroism of a Δ(−)546-di-μ-hydroxo-tetrakis(S-prolinato)dicobalt(iii) complex and NMR study of its interaction with chiral and non-chiral probes in solutions

et al. 2012

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Slow oxidation of cobalt(II) ions by aerial oxygen in the presence of S-prolinate led to isolation of a new m-OH bridged binuclear chiral complex of cobalt(III): Co 2 (m-OH) 2 (S-Pro) 4 . The X-ray structure of this compound was studied. Co III ions are located in N 2 O 4 donor sets containing N and O atoms of S-prolinates at trans(N), cis(O)-or cis(N), trans(O)-positions. Optical properties of Co 2 (m-OH) 2 (S-Pro) 4 were investigated by means of electronic and circular dichroism spectroscopy providing data for comparison with the corresponding mononuclear complex of S-prolinate, cis-(À)-Co(S-Pro) 3 , as well as with other previously reported m-OH bridged cobalt(III) complexes. CD spectra also confirmed that no racemization of S-prolinate occurred during synthesis. The solution behaviour of Co 2 (m-OH) 2 (S-Pro) 4 in the presence of various organic acids was studied by 1 H and 13 C NMR techniques evidencing specific interactions between carboxylic groups of the substrate and hydrogen-bonding groups of the Co 2 (m-OH) 2 (S-Pro) 4 molecule. Relying on the NMR spectroscopy results, the most probable models of binding between Co 2 (m-OH) 2 (S-Pro) 4 and S-proline as well as N-benzoylated a-amino acids were discussed. Chart 1 Simplified representation of the most stable ligand configuration in M 2 (m-OH) 2 (S-Pro) 4 (M = Cr III reported by Oki et al., 33 M = Co III in this publication).

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Section: Circular Dichroismmentioning

confidence: 99%

Synthesis, structure, circular dichroism of a Δ(−)546-di-μ-hydroxo-tetrakis(S-prolinato)dicobalt(iii) complex and NMR study of its interaction with chiral and non-chiral probes in solutions

et al. 2012

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“…7,11 The spectroscopic properties (λ max /nm, ε max /(10 dm 2 mol −1 ) ) and analytical data of these chelates are as follows: , m 0 ) was measured in the same manner as in previous studies. [6][7][8][9][10][11] The measurement was repeated at least four times at each temperature, and the errors defined as the deviations at the 95% confidence levels, were less than 2% of the mean values of these individual experimental values in most cases.…”

Section: Methodsmentioning

confidence: 99%

“…In a series of investigations, I have reported on the dissolution behavior of fac-(+)- [Co(L-aa) 3 ] in water, 6,7 3 ], [8][9][10] and the hydrophobic interaction of 3 ] with tetrabutylammonium ion. 11 These investigations suggest that various [Co(aa) 3 ] may provide useful information about the interactions of the side chains of amino acids with their surroundings.…”

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confidence: 99%

Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)

Yoshimura¹

2002

Bulletin of the Chemical Society of Japan

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The solubilities of soluble mer-(-)-isomers of various tris(amino acidato)cobalt(III) ([Co(aa)3]) in water were determined over the temperature range 5 to 50 °C. From these data the standard free energy (ΔdisG°), enthalpy (ΔdisH°), and entropy of dissolution (ΔdisS°) at 25 °C were estimated and compared with the values reported for mer-(+)-, fac-(-)-, and fac-(+)-isomers of [Co(aa)3]. The solubilities of these isomers increase in the order fac-(+)- < fac-(-)- < mer-(+)- < mer-(-)-isomers for [Co(aa)3] synthesized from amino acids with longer side chains than 2-aminobutyric acid. On the other hand, the increasing sequence of the solubilities for tris(L-alaninato)cobalt(III) ([Co(L-ala)3]) and tris(L-serinato)cobalt(III) ([Co(L-ser)3]) is fac-(+)- < mer-(+)- < fac-(-)- < mer-(-)-isomers. The solubility differences between the mer- and fac-isomers and between the (-)- and (+)-isomers are discussed based on the differences of ΔdisH° and TΔdisS° among these isomers. Furthermore, the influence of introducing hydroxyl and methyl groups into the side chains of the amino acids on the dissolution behavior of [Co(aa)3] is discussed.

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Salt effect on the solubility of mer-(+)-tris(L-alaninato)cobalt(III)

Yoshimura¹

1998

Can. J. Chem.

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The effect of NaF, NaCl, NaBr, NaI, NaNO3, CH3COONH4, NaH2PO4, and (NH4)2SO4 on mer-(+)-tris(L-alaninato)cobalt(III) (mer-(+)-[Co(L-ala)3]) was examined by determining the solubility of the chelate. While the solubility of mer-(+)-[Co(L-ala)3] (salting-in effect) increased with the addition of NaCl, NaBr, NaI, and NaNO3, the solubility (salting-out effect) decreased with the addition of NaF, CH3COONH4, and NaH2PO4. In low salt concentration (NH4)2SO4 caused slight salting-in, but in salt concentration >0.5 mol dm-3 (NH4)2SO4 brought about salting-out. The magnitude of the salting-in effect increased in the order of NaCl < NaNO3 < NaBr < NaI. The standard enthalpy (Δ Hos) and entropy (Δ Sos) of dissolution for mer-(+)-[Co(L-ala)3] were estimated from the temperature dependence of the solubility. When Δ Hos was plotted against T Δ Sos , a single-correlation straight line was obtained for the salts that brought about the salting-in effect. On the basis of these findings, the origin of the salting-in effect was discussed. Furthermore, while NaF, NaCl, and NaBr showed larger salting-in effect on fac-tris(glycinato)cobalt(III) (fac-[Co(gly)3]) than on mer-(+)-[Co(L-ala)3], NaI greatly decreased the solubility of fac-[Co(gly)3]. At the present stage, an explanation for this anomalous salting-out effect of NaI cannot be presented.Key words: salt effect, solubility, thermodynamic parameters of dissolution, mer-tris(L-alaninato)cobalt(III), fac-tris(glycinato)cobalt(III).

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Specific Salt Effect on the Solubility of fac-Tris(α-amino acidato)cobalt(III)

Cited by 6 publications

References 15 publications

Synthesis, structure, circular dichroism of a Δ(−)546-di-μ-hydroxo-tetrakis(S-prolinato)dicobalt(iii) complex and NMR study of its interaction with chiral and non-chiral probes in solutions

Synthesis, structure, circular dichroism of a Δ(−)546-di-μ-hydroxo-tetrakis(S-prolinato)dicobalt(iii) complex and NMR study of its interaction with chiral and non-chiral probes in solutions

Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)

Salt effect on the solubility of mer-(+)-tris(L-alaninato)cobalt(III)

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