Zinc(II) complexes with hydroxocarboxylates and mixed metal species with tin(II) in different salts aqueous solutions at different ionic strengths: formation, stability, and weak interactions with supporting electrolytes

SALMO and S3M: A Saliva Model and a Single Saliva Salt Model for Equilibrium Studies

“…Higher log X exp⁡ values than corresponding log X stat indicate that the formation of mixed species is thermodynamically favored and are a numerical index of the extra stability of mixed species with respect to simple ones. This extra stability has been observed for several systems, providing evidence of the formation of various mixed species (like it has been supposed in this paper), which are able to affect the speciation and the thermodynamic properties of systems where they are formed [ 56 – 62 ].…”

The Control of pH and Ionic Strength Gradients on the Interaction of Low-Molecular-Weight Organic Acids and Siderophores

“…The equilibrium model that gave the best statistical fit and chemically sensible values included one zinc(II)-citrate species which has not previously been identified, namely; [Zn(OH)3Cit] 4-, which exists only above pH 9. However, it did not include [ZnCit2] 4-, a species that has been identified in previous studies (Cigala et al, 2015b). We could detect the formation of…”

“…The stability constants reported in the literature for the zinc(II)/citrate system are inconsistent (Capone et al, 1986;Cigala et al, 2015b;Daniele et al, 1988;Field et al, 1975;Li et al, 1959;Matsushima, 1963). For example, the stability constant reported for [ZnCit]in 0.1 M KNO3 varies by 1.36 log units (Capone et al, 1986;Field et al, 1975 (Cigala et al, 2015a). The equilibrium model that gave the best statistical fit and chemically sensible values included one zinc(II)-citrate species which has not previously been identified, namely; [Zn(OH)3Cit] 4-, which exists only above pH 9.…”

“…Stability constants measured at any other conditions are conditional (log β), their value depends on the chemical and physical conditions (ionic strength, temperature, and pressure) under which they were measured (Cigala et al, 2015a(Cigala et al, , 2013. To delineate the ionic strength stability field for metal-LMWOA and metal-siderophore complexes, we need to know stability constants at many different ionic strengths within an environmentally relevant sampling range (i.e., 0 -1 M) in the same electrolyte.…”

Interaction of N-acetyl-l-cysteine with Na+, Ca2+, Mg2+ and Zn2+. Thermodynamic aspects, chemical speciation and sequestering ability in natural fluids

“…The equilibrium constants of histidine, cysteine and their ternary mixed species were taken from Hallmann [ 76 ], as well as the simple species of Zn 2+ with the third amino-acid, indicated as Gly − but accounting for all the others; for the mixed species the following were considered (log β in parenthesis): Zn(Gly)(His) 0 (aq) (11.6), ZnH(Gly)(His) + (19.55), ZnH 2 (Gly)(His) 2+ (26.35), ZnH(Gly) 2 (His) 0 (aq) (23.10) and ZnH(Gly)(His) 2 0 (aq) (22.79). As regards the other ligands, data of H + /Ca 2+ /Mg 2+ with OH − , Cl − , SO 4 2− , CO 3 2− , PO 4 3− and Gly − were calculated from [ 73 ], data for Zn 2+ /PO 4 3− and Zn 2+ /CO 3 2− systems were elaborated from [ 65 ], those of Zn 2+ /Cit 3− from [ 77 ], glutathione protonation constants and interaction with Ca 2+ and Mg 2+ from [ 78 ]. The concentration of low molecular weight ions in blood plasma was taken from Lentner [ 79 ] and it is reported in Table S8, the values of the equilibrium constants of all the species considered in Table S10.…”