Cu2+-Citrate Dimer Complexes in Aqueous Solutions


 Cu2  solutions, UV-Vis spectra, Cu2 -Citrate-dimer, Potentiometric titrations, Speciation diagrams..

How to Cite

Yahia Z. Hamada, Robin Cox, & Hasan Hamada. (2015). Cu2+-Citrate Dimer Complexes in Aqueous Solutions. Journal of Basic & Applied Sciences, 11, 583–589.


The UV-Vis spectra, speciation diagrams, and potentiometric profiles for Cu2+-citrate complexesin aqueous solutions are presented. As the pH increases from 2.29 to 5.15, the UV-Vis spectral profile of the Cu2+-citrate complexes showed a blue shift from 820 nm to 760 nm. We have set the conditions to construct the speciation diagram as follow: Cu2+:citric acid was in 1:1 ratio with concentration of 1.0 x 10-4 mol.L-1, 0.1023 mol.L-1 NaOH solution, and pKw = 13.781 ± 0.006 taken from Sweeton, Mesmer, and Baes. The current report is the first potentiometric study that has taken into accounts two Cu-Cit dimeric species to be refined simultaneously. These spectroscopic and potentiometric data are discussed which augment what had been reported in the literature.


McKee DJ, Frieden E. Binding of transition metal ions by ceruloplasmin (ferroxidase). Biochemistry 1971; 10(21): 3880-3883.

Freeman S, Daniel E. Dissociation and reconstitution of human ceruloplasmin. Biochemistry 1973; 12(23): 4806-4810.

Dawson JH, Dooley DM, Clark R. Stephens PJ, Gray HB. Spectroscopic studies of ceruloplasmin. Electronic structures of the copper sites. J Am Chem Soc 1979; 101(17): 5046-5053.

Ha-Duong NT, Eid C, He?madi M, and El Hage Chahine J-M. In vitro Interaction between Ceruloplasmin and Human Serum Transferrin. Biochemistry 2010; 49(48): 10261-10263.

Noyer M, Putnam FW. Circular dichroism study of undegraded human ceruloplasmin. Biochemistry 1981 20(12): 3536-3542.

Koschinsky ML, Chow BKC, Schwartz J, Hamerton JL, MacGillivray RTA. Isolation and characterization of a processed gene for human ceruloplasmin. Biochemistry 1987; 26(24): 7760-7767.

Mukhopadhyay CK, Fox PL. Ceruloplasmin Copper Induces Oxidant Damage by a Redox Process Utilizing Cell-Derived Superoxide as Reductant. Biochemistry 1998; 37(40): 14222-14229.

Sedlak E, Wittung-Stafshede P. Discrete Roles of Copper Ions in Chemical Unfolding of Human Ceruloplasmin. Biochemistry 2007; 46(33): 9638-9644.

Brewer GA, Sinn E. Reexamination of a cytochrome oxidase model. A noncoupled iron-copper binuclear complex. Inorg Chem 1984; 23(16): 2532-2537.

Serr BR, Headford CEL, Anderson OP, Elliott CM, Schauer CK, Akabori K, Spartalian K, Hatfield WE, Rohrs BR. Cytochrome c oxidase models: iron(III) porphyrin-copper(II) complexes with sulfur bridges. Inorg Chem 1990; 29(14): 2663-2671.

Serr BR, Headford CEL, Anderson OP, Elliott CM, Spartalian K, Fainzilberg VE, et al. Cytochrome c oxidase models: a dinuclear iron(III) porphyrin-copper(II) complex with a sulfur bridge. Inorg Chem 1992; 31(26): 5450-5465.

Kauffmann KE, Goddard CA, Zang Y, Holm RH, Münck E. Mössbauer and Magnetization Studies of Heme?Copper-Bridged Assemblies Pertinent to Cytochrome c Oxidase. Inorg Chem 1997; 36(6): 985-993.

Brewer CT, Brewer GA. Heteronuclear imidazolate-bridged complexes of iron(III) porphyrins and copper(II). Toward modeling of cytochrome c oxidase. Inorg Chem 1987; 26(20): 3420-3422.

Beem KM, Richardson DC, Rajagopalan KV. Metal sites of copper-zinc superoxide dismutase. Biochemistry 1977; 16(9): 1930-1936.

St. Clair CS, Gray HB, Valentine JS. Spectroelectrochemistry of copper-zinc superoxide dismutase. Inorg Chem 1992; 31(5): 925-927.

Lamb AL, Torres AS, O'Halloran TV, Rosenzweig AC. Heterodimer Formation between Superoxide Dismutase and Its Copper Chaperone. Biochemistry 2000; 39(48): 14720-14727.

Hart PJ, Balbirnie MM, Ogihara NL, Nersissian AM, Weiss MS, Valentine JS, Eisenberg D. A Structure-Based Mechanism for Copper?Zinc Superoxide Dismutase. Biochemistry 1999; 38(7): 2167-2178.

de Freitas DM, Valentine JS. Phosphate is an inhibitor of copper-zinc superoxide dismutase. Biochemistry 1984; 23(9): 2079-2082.

Ellerby LM, Cabelli DE, Graden JA, Valentine JS. Copper?Zinc Superoxide Dismutase:? Why Not pH-Dependent? J Am Chem Soc 1996; 118(28): 6556-6561.

Champloy F, Benali-Chérif N, Bruno P, Blain I, Pierrot M, Réglier M. Studies of Copper Complexes Displaying N3S Coordination as Models for CuB Center of Dopamine ?-Hydroxylase and Peptidylglycine ?-Hydroxylating Monooxygenase. Inorg Chem 1998; 37(16): 3910-3918.

Santra BK, Reddy PAN, Nethaji M, Chakravarty AR. Structural Model for the CuB Site of Dopamine ?-Hydroxylase:? Crystal Structure of a Copper(II) Complex Showing N3OS Coordination with an Axial Sulfur Ligation. Inorg Chem 2002; 41(16): 4304-4304.

Santras BK, Reddy PAN, Nethaji M, Chakravarty AR. Structural Model for the CuB Site of Dopamine ?-Hydroxylase:? Crystal Structure of a Copper(II) Complex Showing N3OS Coordination with an Axial Sulfur Ligation. Inorg Chem 2002; 41(5); 1328-1332.

Cole JL, Avigliano L, Morpurgo L, Solomon EI. Spectroscopic and chemical studies of the ascorbate oxidase trinuclear copper active site: comparison to laccase. J Am Chem Soc 1991; 113(24): 9080-9089.

Strothkamp KG, Dawson CR. Quaternary structure of ascorbate oxidase. Biochemistry 1974; 13(3): 434-440.

Mei G, Di Venere A, Buganza M, Vecchini P, Rosato N, Finazzi-Agro A. Role of Quaternary Structure in the Stability of Dimeric Proteins:? The Case of Ascorbate Oxidase. Biochemistry 1997; 36(36): 10917-10922.

Gaspard S, Monzani E, Casella L, Gullotti M, Maritano S, Marchesini A. Inhibition of Ascorbate Oxidase by Phenolic Compounds. Enzymatic and Spectroscopic Studies. Biochemistry 1997; 36(16): 4852-4859.

Meyer TE, Marchesini A, Cusanovich MA, Tollin G. Direct measurement of intramolecular electron transfer between type I and type III copper centers in the multi-copper enzyme ascorbate oxidase and its type II copper-depleted and cyanide-inhibited forms. Biochemistry 1991; 30(18): 4619-4623.

Duff AP, Cohen AE, Ellis PJ, Kuchar JA, Langley DB, Shepard EM, et al. The Crystal Structure of Pichia pastoris Lysyl Oxidase. Biochemistry 2003; 42(51): 15148-15157.

Bollinger JA, Brown DE, Dooley DM. The Formation of Lysine Tyrosylquinone (LTQ) Is a Self-Processing Reaction. Expression and Characterization of a Drosophila Lysyl Oxidase. Biochemistry 2005; 44(35): 11708-11714.

Rebecchi KR, Go EP, Xu L, Woodin CL, Mure M, Desaire H. A General Protease Digestion Procedure for Optimal Protein Sequence Coverage and Post-Translational Modifications Analysis of Recombinant Glycoproteins: Application to the Characterization of Human Lysyl Oxidase-like 2 Glycosylation. Anal Chem 2011; 83(22): 8484-8491.

Pyrz JW, Karlin KD, Sorrell TN, Vogel GC, Que L Jr. Resonance Raman studies of phenolate-bridged binuclear copper complexes. Relevance to hemocyanin and tyrosinase. Inorg Chem 1984; 23(26): 4581-4584.

Casella L, Dipartimento EM, Gullotti M, Cavagnino D, Cerina G, Santagostini L, Ugo R. Functional Modeling of Tyrosinase. Mechanism of Phenol ortho-Hydroxylation by Dinuclear Copper Complexes. Inorg Chem 1996; 35(26): 7516-7525.

Peyroux E, Ghattas W, Hardré R, Giorgi M, Faure B, Simaan AJ, Belle C, Réglier M. Binding of 2-Hydroxypyridine-N-oxide on Dicopper(II) Centers: Insights into Tyrosinase Inhibition Mechanism by Transition-State Analogs. Inorg Chem 2009; 48(23): 10874-10876.

Casella L, Carugo O, Gullotti M, Garofani S, Zanello P. Hemocyanin and tyrosinase models. Synthesis, azide binding, and electrochemistry of dinuclear copper(II) complexes with poly(benzimidazole) ligands modeling the met forms of the proteins. Inorg Chem 1993; 32(10): 2056-2067.

Monzani E, Quinti L, Perotti A, Casella L, Gullotti M, Randaccio L, et al. Tyrosinase Models. Synthesis, Structure, Catechol Oxidase Activity, and Phenol Monooxygenase Activity of a Dinuclear Copper Complex Derived from a Triamino Pentabenzimidazole Ligand. Inorg Chem 1998; 37(3): 553-562.

Kendall EC. A new method for the determination of the reduced sugar. J Am Chem Soc 1912; 34(3): 317-341.

Warner RC, Weber I. The Cupric and Ferric Citrate Complexes. J Am Chem Soc 1953; 75(20): 5086-5094.

Mastropaolo D, Powers DA, Potenza JA, Schugar HJ. Inorg Chem 1976; 15(6): 1444-49.

Hamada YZ, Carlaon BL, Shank JT. Potentiometric and UV-Vis spectroscopy studies of citrate with the hexaquo Fe3+ and Cr3+ metal ions. Syn Reac Inorg Metal-Org Chem 2003; 33(8): 1425-1440.

Hamada YZ, Zhepeng W, Harris WR. Competition between transferrin and serum ligands citrate and phosphate for the binding of aluminum. Inorg Chem 2003; 42: 3262-3273.

Hamada YZ, Bayakly N, George D, Greer T. Speciation of Molybdenum(VI)- Citric Acid Complexes in Aqueous Solutions, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry 2008; 38(8): 664-668.

Martell AE Smith RM, Motekaitis RJ. Critical Stability Constants Database, Version 6.0, 2001 NIST, Texas A & M University, College Station, TX, USA.

Alderighi L, Gans P, Ienco A, Perters D, Sabatini A, Vacca A. Hyperquad simulation and speciation (Hyss): a utility program for the investigation of equilibria involving soluble and partially soluble species. Coord Chem Rev 1999; 184: 311-318.

Sweeton FH, Mesmer RE, Baes Jr., CF. Acidity measurements at elevated temperature. VII. Dissociation of water. J Sol Chem 1974; 3: 191-214.

Kotsakis N, Raptopoulou CP, Tangoulis V, Giapintzakis J, Jakusch T, Kiss T, Salifoglou A. Correlation of synthetic, spectroscopic, structural, and speciation studies in the biologically relevant cobalt(II)-citrate system: The tale of the first aqueous dinuclear cobalt(II)-citrate complex. Inorg Chem 2003; 42: 22-31.

Dakanali M, Raptopoulou CP, Terzis A, Lakatos A, Lakatos A, Kiss T, Salifoglou A. A novel dinuclear species in aqueous distribution of aluminum in the presence of citrate. Inorg Chem 2003; 42: 252-254.

Matzapetakis M, Kourgiantakis M, Dakanali M, Raptopoulou CP, Terzis A, Lakatos A, Lakatos A, Kiss T, Banyai I, Mavromoustakos T, Salifoglou A. Synthesis, pH-dependent structural characterization, and solution behavior of aqueous aluminum and gallium citrate complexes. Inorg Chem 2001; 40: 1734-1744.

Kaliva M, Raptopoulou CP, Terzis A, Salifoglou A. Systematic studies on pH-dependent transformation of dinuclear vanadium(V)-citrate complexes in aqueous solutions. A perspective relevance to aqueous vanadium(V)-citrate speciation. J Inorg Biochem 2003; 93: 161-173.

Abbay G, Gilbert TW. Chromium(III)-citrate complexes: A study using ion exchange and isotachophoresis. Polyhedron 1986; 5(11): 1839-1844.

Lippard S, Shweky I, Bino A, Goldberg DP. Synthesis, structure, and magnetic properties of two dinuclear iron(III) complexes. Inorg Chem 1994; 33: 5161-5162.

Spiro TG, Pape L, Saltman P. The hydrolytic polymerization of ferric citrate. I. The chemistry of the polymer. J Am Chem Soc 1967; 89: 5555-5559.

Hamada Y, Bayakly ZN, Peipho A, Carlson B. Accurate potentiometric studies of chromium-citrate and ferric-citrate complexes in aqueous solutions at physiological and alkaline pH-values. Synthesis and Reactivity of Inorganic and Metal-Organic and Nano-Metal Chemistry 2006; 36: 469-476.

Timberlake CF. Iron–malate and iron–citrate complexes. J Chem Soc 1964; 5078-5085.

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Copyright (c) 2015 Journal of Basic & Applied Sciences