Stabilities of the Ternary Complexes of Copper(II) with Substituted 1,10-Phenanthrolines and Some Amino Acids in Aqueous Solution
In this study the binary and ternary complexes of copper(II) with substituted 1,10-phenanthrolines [s-phen: 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dmphen) and 5-nitro-1,10-phenanthroline (nphen)] and l-amino acids [aa: l-phenylalanine (phe), l-tyrosine (tyr) and l-tryptophan (trp)] have been investigated using potentiometric methods in 0.1 mol·L−1 KCl aqueous ionic media at 298.2 K. The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the “BEST” software package. It was inferred that the aromatic 1,10-phenanthrolines act as a primary ligand in the ternary complexes, while the oxygen and nitrogen donor-containing amino acids are secondary ligands. The observed values of Δlog10 K indicate that the ternary complexes are more stable than the binary ones, suggesting no interaction takes place between the ligands in the ternary complexes. The magnitudes of the measured stability constants of all of the ternary complexes are in the order [Cu(s-phen)(trp)]+ > [Cu(s-phen)(tyr)]+ > [Cu(s-phen)(phe)]+, which is identical to the sequence found for the binary complexes of Cu(II) with the amino acids. When the substituted 1,10-phenanthroline is changed, the stability constants of the ternary complexes decrease in the following order: [Cu(dmphen)(aa)]+ > [Cu(phen)(aa)]+ > [Cu(nphen)(aa)]+.
KeywordsCopper(II) 1,10-Phenanthroline 4,7-Dimethyl-1,10-phenanthroline 5-Nitro-1,10-phenanthroline l-Amino acids l-Phenylalanine l-Tyrosine l-Tryptophan Stability constants Potentiometric methods
We thank the Research Fund of Uludag University for financial support given to this research project (Project Number UAP(F)-2011/71). This study is a part of MS thesis of the first author accepted on 16 January 2013 by the Graduate School of Natural and Applied Sciences of Uludag University.
- 1.May, P.M., Williams, D.R.: In: Sigel, H. (ed.) Metal Ions in Biological Systems Properties of Copper, vol. 12. Marcel Dekker, New York (1981)Google Scholar
- 2.Sigel, H. (ed.): Metal Ions in Biological Systems, vol. 13. Marcel Dekker, New York (1981)Google Scholar
- 4.Ramakrishnan, S., Rajendiran, V., Palaniandavar, M., Periasamy, V.S., Srinag, B.S., Krishnamurthy, H., Akbarsha, M.A.: Induction of cell death by ternary copper(II) complexes of l-tyrosine and diimines: role of coligands on DNA binding and cleavage and anticancer activity. Inorg. Chem. 48, 1309–1322 (2009)CrossRefGoogle Scholar
- 6.Devi, K.V.S., Raju, B.R., Rao, G.N.: Effect of dielectric constant on protonation equlibria of L-dopa and 1,10-phenanthroline in dioxan–water mixtures. Acta Chim. Slov. 57, 398–404 (2010)Google Scholar
- 10.Bandyopadhyay, S., Mandal, A.K., Aditya, S.: Thermodynamics of 2,2′-dipyridinium ion and 1,10-phenanthrolinium ion in tert-butanol–water and glycerol–water media at 25. J. Indian Chem. Soc. 58, 467–473 (1981)Google Scholar
- 11.Bandyopadhyay, S., Mukherjee, G.N., Drew, M.G.B.: Equilibrium studies on mixed ligand complex formation of Co(II), Ni(II), Cu(II) and Zn(II) with N-(2-hydroxybenzyl)-l-histidine(H2hb-L-his) and typical N, N donor ligands: crystal structure of [Ni(hb-L-his) (bipyridine)] H2O complex. Inorg. Chim. Acta 359, 3243–3251 (2006)CrossRefGoogle Scholar
- 12.Eun-Jun, G., Xia, L., Qi-Tao, L.: Study on electronic effect and aromatic ring stacking of Pd(II)–aromatic diamine–aminoacid ternary complexes. Chinese J. Inorg. Chem. 18, 442–446 (2002)Google Scholar
- 14.Yasuda, M., Sone, K., Yamasaki, K.: Stability of zinc and cadmium complexes with some methyl derivatives of 1,10-phenanthroline and 2,2′-bipyridine. J. Am. Chem. Soc. 60, 1667–1668 (1956)Google Scholar
- 25.Mohan, A., Yogi, D.S., Kumar, G.N., Mohan, M.S.: Influence of electronic, steric and stacking interactions in ternary Ni(II) and Cu(II) complexes containing 2,2′,2′’-terpyridine and a series of amino acids. Indian J. Chem. 32A, 785–788 (1993)Google Scholar
- 26.Yamauchi, O., Odani, A.: Structure-stability relationship in ternary copper(II) complexes involving aromatic amines and tyrosine or related amino acids. ıntramolecular aromatic ring stacking and its regulation through tyrosine phosphorylation. J. Am. Chem. Soc. 107, 5938–5945 (1985)CrossRefGoogle Scholar
- 31.Martell, A.E., Motekaites, R.J.: Determination and Use of Stability Constants. VCH Publishers, New York (1989)Google Scholar
- 34.Schwarzenbach, G., Flaschka, A.: Complexometric Titrations. Methuen, New York (1969)Google Scholar