Ternary Complexes Formed Among Pd(II) Ions, Nucleobases, Nucleosides, Nucleotides and Some Biologically Important Compounds

Potentiometric measurements have been performed at (25.0 ± 0.1) °C and ionic strength I = 0.1 mol·L−1 KNO3 for the interaction of guanine, thymine, uracil, aminouracil, guanosine, inosine, cytidine, guanosine 5′-monophosphate, adenosine 5′-diphosphate, adenosine 5′-triphosphate and palladium Pd(II) with the biologically important secondary ligands glycine, leucine, N,N-bis(2-hydroxyethyl) glycine, N-[tris(hydroxymethyl)methyl] glycine, d-2-t-butylglycine and Boc-N-methyl-l-leucine. The formation of various 1:1:1 ternary complexes and 1:1:2 quaternary complex species as well as the polynuclear species was inferred from the potentiometric pH-titration curves. The experimental conditions were selected such that self-association of the nucleobases, nucleosides or nucleotides and their complexes due to stacking interaction is negligibly small; that is, the normal monomeric protonated ternary complexes were studied. Formation of the ternary complexes of some systems was confirmed using cyclic voltammetry, differential pulse voltammetry and conductance measurements in solution.