Binary and Ternary Complexes of Copper(II) Involving N,N,N′,N′-Tetramethylethylenediamine (Me4en) and Various Biologically Relevant Ligands

Binary and ternary complexes of copper(II) involving N,N,N′,N′-tetramethylethylene-diamine (Me4en) and various biologically relevant ligands containing different functional groups are investigated. The ligands (L) used are dicarboxylic acids, amino acids, peptides and DNA unit constituents. The ternary complexes of amino acids, dicarboxylic acids or peptides are formed by simultaneous reactions. The results showed the formation of Cu(Me4en)(L) complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants was examined. Peptides form both Cu(Me4en)(L) complexes and the corresponding deprotonated amide species Cu(Me4en)(LH−1). The ternary complexes of copper(II) with (Me4en) and DNA are formed in a stepwise process, whereby binding of copper(II) to (Me4en) is followed by ligation of the DNA components. DNA constituents form both 1:1 and 1:2 complexes with Cu(Me4en)2+. The concentration distribution of the complexes in solution was evaluated. [Cu(Me4en)(CBDCA)] and [Cu(Me4en)(malonate)] are isolated and characterized by elemental analysis and infrared measurements.