Solvent influence upon complexation of N-phenylaza-15-crown-5 with UO2 2+ cation in binary mixed non-aqueous solvents

Abstract

The complexation reaction of N-phenylaza-15-crown-5 (PhA15C5) with UO 2 2? cation was studied in acetonitrile-methanol (AN-MeOH), acetonitrile-butanol (ANBuOH), acetonitrile-dimethylformamide (AN-DMF) and methanol-propylencarbonate (MeOH-PC) binary solutions, at different temperatures by conductometry method. The conductance data show that the stoichiometry of the complex formed between PhA15C5 with UO 2 2? cation in most cases is 1:1 [M:L], but in some solvent systems a 1:2 [M:L 2 ] complex is formed in solutions. The results revealed that, the stability constant of (PhA15C5ÁUO 2 ) 2? complex in the binary mixed solvents varies in the order: AN-BuOH[ANMeOH[AN-DMF. In the case of the pure organic solvents, the sequence of the stability of the complex changes as: AN[PC[BuOH[DMF. A non-linear relationship was observed for changes of logK f of (PhA15C5ÁUO 2 ) 2? complex versus the composition of the binary mixed solvents. The corresponding standard thermodynamic parameters (DH c°, DS c°) were obtained from temperature dependence of the stability constant. The results show that the values and also the sign of these parameters are influenced by the nature and composition of the mixed solvents.

Synergistic Efficiency of 2-[(1-Aza-15-crown-5)-1-ylmethyl)]-4-(phenyldiazenyl)-naphthalen-1-ol in the Liquid Extraction of Light Lanthanoid(III) Ions with 4-Benzoyl-3-phenyl-5-isoxazolone: The Role of Aza-Crown and Azo-Dye Fragments on the Extraction Ability

“…The obtained equilibrium constants log K I,S are between 2 and 4 orders of magnitude higher using PDN1A15C5 or BA15C5, and these agents improve the extraction efficiency better as compared with cases when the CEs are used as a second ligand. These data are in conformity with previous studies reporting that aza-crown ethers are more suitable complexing agents for metal cations than the corresponding crown ethers. , It is interesting to point out that the rates of extraction are different for the two groups of synergistic agents due to the different extraction mechanisms and species. The results show that the nitrogent containing ligands are more effective synergist than the crown ether compound with only oxygen donors. , Ensor and Shah reported that 222BB provides ∼10 4 enhancement while 15C5 shows ∼10 2 increase in the overall extraction equilibrium using HTTA toward lanthanoids .…”

“…These data are in conformity with previous studies reporting that aza-crown ethers are more suitable complexing agents for metal cations than the corresponding crown ethers. 26,44 It is interesting to point out that the rates of extraction are different for the two groups of synergistic agents due to the different extraction mechanisms and species. The results show that the nitrogent containing ligands are more effective synergist than the crown ether compound with only oxygen donors.…”