Speciation of the ternary complexes formed between copper(II), salicylic acid and small blood serum bioligands

Abstract In this work we present the speciation of the ternary complexes formed between the copper(II)-salicylate (Sal 2 − ) system and the small blood serum bioligands, such as lactate (Lac − ), oxalate (Ox 2 − ), citrate (Cit 3 − ) and phosphate (PO 4 3 − ). The speciation of the ternary systems were studied by pH-potentiometry at 25 °C and using an ionic strength I  = 1.0 mol·dm − 3 KNO 3 . In the Cu(II)-Sal 2 − − Lac − system the complexes [Cu(Sal)(Lac)(OH)] 2 − , [Cu(Sal)(Lac)(OH) 2 ] 3 − and [Cu(Sal) 2 (Lac)] 3 − were detected. In the case of the Cu(II)-Sal 2 − –Ox 2 − system the complexes [Cu(Sal)(Ox)] 2 − , [Cu(Sal)(Ox)(OH)] 3 − and [Cu(Sal)(Ox)(OH) 2 ] 4 − were observed. In the Cu(II)-Sal 2 − − Cit 3 − system the species [Cu(Sal)(H 2 Cit)] − , [Cu(Sal)(HCit)] 2 − , [Cu(Sal)(Cit)] 3 − and [Cu(Sal)(Cit)(OH)] 4 − were detected and in the Cu(II)-Sal 2 − –PO 4 3 − system the complexes [Cu(Sal)(H 2 PO 4 )] − , [Cu(Sal)(HPO 4 )] 2 − and [Cu(Sal)(PO 4 )] 3 − were observed.