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Jóźwiak, Janina; Blum, Alain

doi:10.1007/bf01796843

Cited by 2 publications

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“…Most of the studies on crown ether complexation have been carried out in pure aqueous, organic and also in some aqueous-organic mixed solvents [6][7][8][9][10][11], but the data concerning the complex formation in mixed organic solvents are scarce [12,13]. The accumulation of a large number of such data will allow one to analyze the influence of the properties of mixed organic solvents, including especially their solvation capabilities on the process of complex formation, and also to investigate the order of stability and selectivity of the metal ion-crown ether complexes with the nature and composition of these mixed solvents.…”

Section: Introductionmentioning

confidence: 99%

Conductometric study of complexation process between dibenzo-18-crown-6 and K+, Na+, and La3+ cations in some binary mixed non-aqueous solvents

Khoshnood

Teymoori

Hatami

et al. 2015

Russ. J. Phys. Chem.

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The complexation reactions between K + , Na + , and La 3+ cations and the macrocyclic ligand dibenzo-18-crown-6 (DB18C6) were studied in acetionitrile (AN)-dimethylformamide (DMF) binary mixtures. Also, the complexation of K + and Na + in 50% ethanol (EtOH)-50% DMF and 50% EtOH-50% AN binary mixtures was studied. The conductivity data show that the stochiometry of all the complexes is 1 : 1. A non-linear behavior was observed for the log K f variation vs. composition of binary solvent, which was discussed in terms of heteroselective solvation and solvent-solvent interactions in binary solutions. It was found that the stability order of the complexes changes with composition of the mixed solvents. The stability sequence for AN-DMF (25 and 50 mol % DMF) solutions and pure AN at 25°C is [K(DB18C6)] + > [Na(DB18C6)] + > [La(DB18C6)] 3+ . However, at 75 mol % DMF it changes to [Na(DB18C6)] + > [K(DB18C6)] + > [La(DB18C6)] 3+ . The thermodynamical values ( , ) for these complexation reactions were determined from the temperature dependence of the stability constants. The thermodynamics of the complexation reactions is affected by the nature and composition of the mixed solvents.

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