Ternary complex formation of the copper (II)-2,2′-Bipyridine system with some amino acids

In this work we present a stability and speciation study for the formation of binary and ternary metal complexes obtained from the interaction of Cu(II), 2,2’-Bipyridine and the Amino acids: Glycine (HGly), Proline (HPro), α-Alanine (Hα-Ala), β-Alanine (Hβ-Ala), Leucine (HLeu), Isoleucine (HIso), Valine (HVal), Methionine (HMet), Aspartic acid (H2Asp), Glutamic acid (H2Glu), Serine (HSer), Threonine (HThr), Histidine (HHis), Phenylalanine (HPhe), and Tryptophan (HTry), in aqueous solution at 25 °C using 1.0 M KNO3 as the ionic medium. The overall stability constants were established based on the analysis of potentiometric results using the software LETAGROP. The relative stability of the ternary complexes was compared with the corresponding one of the binary complexes. The concentration distribution of various species, formed in aqueous solution, was also evaluated as a function of pH. In addition, the antibacterial properties of some of the ternary complexes were compared using the well-known Kirby-Bauer agar diffusion method. The complexes were in-situ synthetized considering the obtained potentiometric results, and the antibacterial activity was evaluated against Escherichia coli and Staphylococcus aureus, only showing activity against the microorganisms Staphylococcus aureus. These results suggest that Cu(II)-2,2’-Bipyridine-Amino acid complexes have potential as antibacterial agents. [Display omitted] •Formation of binary Cu(II)-Bipy and ternary Cu(II)-Bipy-Amino acid complexes in water was reported.•Stability constants were determined from potentiometric data with LETAGROP software.•Appropriate comparisons between the binary and ternary systems were carried out.•Activity against Staphylococcus aureus was probed by some ternary complexes