Calcium ions, aqueous stability constants

Even though the stability constants for calcium, barium and strontium cations in nitrobenzene are much higher than that for lithium cation, the translocation of lithium ion from water to nitrobenzene is shifted by about 300 mV negatively when it is used as a base electrolyte, i.e., when [Li+(w)]>>[X(n)] and it coincides with the transfer of alkaline earth metal cation. From a comparison of the standard electrical potential difference and from the calculated half-wave potentials using the stability constant for several cations we have chosen magnesium chloride as a base electrolyte for the aqueous phase. To minimize the base electrolytes current in DPSV we have decreased their concentrations. In the case of magnesium chloride it was 2.5 mM solution in water and 5 mM solution of TBATPB in nitrobenzene. The concentration of the ionophore was 1 mM. 

A study of sucrose interactions with the same raagnesivun and calcium ions showed that both form mono- and di- sucrose adducts, and the isolation of several complexes formed between these metal ions and D-glucurono-1,4-lactone in ethanolic and aqueous solutions has been reported. The interaction in aqueous solution of j8-D-fructose with hydrated salts of Zn(II), Cd(Il), and Hg(ll) has given rise to solid adducts of the type M(D-fructose)Xa.nHaO, X = Br, Cl which were characterised by F.T.-I.R. spectroscopy. X-ray powder diffraction and molar conductivity measurements. Potentiometric pH titration was used to measure the stability constants of the 1 1 complexes formed between a number of cations and tubercidin 5 -monophosphate. The complexation ofCopper(II) ions with sucrose has been studied and a number of complexes were identified. A molecular model has been used to describe the formation of iron(III)-glucosamine complexes in aqueous KOH at various mole ratios. ... 

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