Biomedical Chemistry: Research and Methods, 2018, 1(3), e00043
The 40th Anniversary of the Institute of Physiologically Active Compounds of the Russian Academy of Sciences

1,5-bis[2-(dioxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and its Analogs as Promising Organic Ligands for Copper(II) Binding

V.E. Baulin1*, G.S. Tsebrikova2, D.V. Baulin2, Y.F. Al Ansary3

1Institute of Physiologically Active Compounds of the Russian Academy of Sciences, 1 Severny proezd, Moscow region, Chernogolovka, 142432 Russia,*e-mail:
2Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, 31/4 Leninskii av., Moscow, 119071 Russia
3Mari State University, 1 Lenin Square, Republic of Mary El, Yoshkar-Ola, 424000 Russia

Key words: diphosphonic acids; dissociation constants; copper(II) complexes; stability constants; potentiometry; spectrophotometry

DOI: 10.18097/BMCRM00043

The whole version of this paper is available in Russian.

The dissociation and complexation ability toward Cu(II) of acidic type phosphoryl-containing podands – tetrabasic 1,5-bis[2-(dioxyphosphoryl)-4-ethylphenoxy]-3-oxapentane (L1), dibasic – 1,5-bis[2-(ethoxyhydroxyphosphoryl)-4-ethylphenoxy]-pentane (L2) and also of their carboxylic analogue dibasic 1,5-bis[2-(oxycarbonylphenoxy)]-3-oxapentane (L3) were investigated by spectrophotometric, conductometric and potentiometric methods in water in the presence 5% of dimethyl formamide. Spectrophotometric and conductometric titration data provided evidence for formation of 1 : 1 (M : L) complexes. The dissociation constants were determined and species distribution diagrams for studied acids were obtained by potentiometric method. These data are of interest for the design of binary extragents and medicinal drugs based on the studied ligands. The stability constants of Cu(II) 1: 1 (M : L) complexes were estimated. Analysis of the titration curves suggests that deprotonation forms of the studied ligands react with Cu2+. Substitution of carboxylic groups in acyclic polyesters by phosphonic results in increased stability of the copper(II) complexes

Figure 1. Structural formulas of studied ligands.

Figure 2. Treatment of spectrophotometric data using the Benesi-Hildebrand method.

Figure 3. Curve of conductometric titration of copper(II) solution, a – number of equivalents of added neutralized ligand L4-.

Figure 4. Potentiometric titration curves of free acids and acids in the presence of Cu2+, µ = 0.1 (KCl), the metal : ligand ratio was 1:1; a – number of NaOH moles to 1 mole of acid (L3 (a), L2 (b) и L1 (c)).

Figure 5. Species distribution diagrams for L3 (a), L2 (b), and L1 (c).

Table 1. Dissosiation constants of studied acids (µ = 0.1, KCl).

Table 2. Dissosiation constants of studied acids (µ = 0.1, KCl).


The work was performed on the government assignments no. 0090-2017-0024 and 0081-2014-0015. A part of the work was supported by the Russian Foundation for Basic Research (project no. 18-33-00685) and the Presidium of Russian Academy of Sciences – Russia (program no. 34).


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