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  • Binary and ternary complexe...
    Irto, Anna; Cigala, Rosalia Maria; Alessandrello, Chiara; De Stefano, Concetta; Gattuso, Giuseppe; Crea, Francesco

    Frontiers in chemistry, 04/2023, Volume: 11
    Journal Article

    The speciation of epinephrine ( ) in the presence of alginate ( ) and two biological and environmental relevant metal cations (Cu , UO ) was investigated at = 298.15K, = 0.15-1.00 mol dm in NaCl . The formation of binary and ternary complexes was evaluated and, since epinephrine can behave as a zwitterion, the / interaction was studied by means of DOSY NMR. The dependence of the equilibrium constants on ionic strength was studied using an extended Debye-Hückel type equation and the SIT approach. The effect of temperature was investigated by means of isoperibolic titration calorimetry: the entropic contribution was the driving force for the Cu / complexes formation. The sequestering ability of and on Cu , evaluated by the pL calculation, increased with pH and ionic strength. The determination of pM parameter showed that had a higher Cu affinity with respect to . The formation of / species was also investigated by UV-Vis spectrophotometry and H NMR measurements. The ternary Cu / / and Cu /UO / interactions were also studied. The "extra-stability" calculated for the mixed ternary species confirmed that their formation was thermodynamically favorable.