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The complexation of Cu 2+ with glycine in aqueous solution of an anionic surfactant, sodium dodecyl sulfate, was studied spectrophotometrically. Sodium dodecyl sulfate in concentrations above the critical micellization concentration participates in the complexation. The composition of the complexes and the equilibrium constants of the complexation were determined.Complexation of biologically active metals with physiologically active organic ligands is an urgent line of coordination chemistry, because the coordinationbound metal exhibits considerably higher activity and lower toxicity.Ionic micelles, thanks to their diphilic properties and charged surface, resemble biological membranes and therefore are often chosen as systems simulating the reaction medium of biological substrates [1].We found previously [2] that comenic acid (5-hydroxy-4-pyrone-2-carboxylic acid used in pharmacology) forms ionic associates of various stoichiometries with a cationic surfactant, cetylpyridinium chloride. This work continues a series of studies on interaction of biologically active compounds with surfactants. We have studied the complexation of Cu(II) with glycine in the presence of an anionic surfactant, sodium dodecyl sulfate. Glycine (aminoacetic acid) is one of the most widely occurring amino acids, a component of proteins; it forms complexes with many metal cations. Copper is a metal of vital importance; its stock in a human body is continuously replenished, and the deficiency of copper causes the damage of vessels.The interactions in the system were monitored spectrophotometrically. We recorded the absorption spectra containing equimolar amounts of CuCl 2 and glycine and variable amounts of sodium dodecyl sulfate. To find in what form (monomeric or micellar) sodium dodecyl sulfate participates in the interaction, we determined stalagmometrically the critical micellization concentration of the ternary system CuCl 2 3 glycine3sodium dodecyl sulfate. The critical micellization concentration was 1.5 mM (Fig. 1), i.e., close to that of copper dodecyl sulfate, 1.2 mM [3]. Addition of sodium dodecyl sulfate to the system CuCl 2 3 glycine in concentrations below the critical micellization concentration did not lead to spectral changes, and at concentrations above the critical micellization concentrations the optical density increased and the absorption maximum shifted toward the short-wave region (Fig. 2), suggesting formation of complexes.The spectrophotometric data were processed with the FTMT program [4] based on a search for a minimum of the criterial function F by varying log K i in each iteration.The function being minimized has the form F = 5 5 (D k,e 3 D k,c ) . l 2 , K L l=1 k=1 where K is the number of wavelengths; L, number of 70 60 50 40 30 310 39 38 37 36 lnc Nads [M] Fig. 1. Isotherms of the surface tension of an aqueous solution of the system CuCl 2 !glycine (gl)!sodium dodecyl sulfate (Nads). c CuCl 2 0.02, c gl 0.04 M.

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