Extraction of some univalent cations into phenyltrifluoromethyl sulfone by using sodium dicarbollylcobaltate in the presence of benzo-18-crown-6

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺ (aq) + 1·Na⁺ (org) $ \Leftrightarrow $ 1·M⁺ (org) + Na⁺ (aq) taking place in the two-phase water–phenyltrifluoromethyl sulfone (abbrev. FS 13) system (M⁺ = Li⁺, H₃O⁺, NH₄ ⁺, Ag⁺, Tl⁺, K⁺, Rb⁺, Cs⁺; 1 = benzo-18-crown-6; aq = aqueous phase, org = FS 13 phase) were evaluated. Further, the stability constants of the 1·M⁺ complexes in FS 13 saturated with water were calculated; they were found to increase in the series of $ {\text{Cs}}^{ + } \, < \,{\text{Rb}}^{ + } \, < \,{\text{H}}_{ 3} {\text{O}}^{ + } \, < \,{\text{Ag}}^{ + } \, < \,{\text{Li}}^{ + } \, < \,{\text{NH}}_{4}^{ + } \, < \,{\text{K}}^{ + } \, < \,{\text{Tl}}^{ + } $ .     

Calix[4]arene-bis(t-octylbenzo-18-crown-6) as an extraordinarily effective macrocyclic receptor for the univalent thallium cation

From extraction experiments and $ \gamma $ -activity measurements, the exchange extraction constant corresponding to the equilibrium Tl⁺ (aq) + 1·Cs⁺ (org) ? 1·Tl⁺ (org) + Cs⁺ (aq) taking place in the two-phase water–phenyltrifluoromethyl sulfone (abbrev. FS 13) system (1 = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, org = FS 13 phase) was evaluated as log K _ex (Tl⁺, 1·Cs⁺) = 1.7 ± 0.1. Further, the extraordinarily high stability constant of the 1·Tl⁺ complex in FS 13 saturated with water was calculated for a temperature of 25 °C: log β _org(1·Tl⁺) = 13.1 ± 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1·Tl⁺ was derived. In the resulting 1·Tl⁺ complex, the “central” cation Tl⁺ is bound by eight bond interactions to six oxygen atoms from the respective 18-crown-6 moiety and to two carbons of the corresponding two benzene rings of the parent receptor 1 via cation–π interaction.     

Complexation of the cesium cation with lithium ionophore VIII: extraction and DFT study

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺(aq) + 1·Na ⁺ (nb) = 1·Cs⁺(nb) + Na⁺(aq) taking place in the two-phase water-nitrobenzene system (1 = lithium ionophore VIII; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (Cs⁺, 1·Na⁺) = ?0.5 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Cs⁺) = 4.8 ± 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1·Cs⁺ was derived. In the resulting complex, the “central” cation Cs⁺ is bound by six bond interactions to the corresponding six oxygen atoms of the parent ligand 1.     

Complexation of the cesium cation with nonactin: extraction and DFT study

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺(aq) + A^?(aq) + 1(nb) ? 1·Cs⁺(nb) + A^?(nb) taking place in the two-phase water–nitrobenzene system (A^? = picrate, 1 = nonactin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (1·Cs⁺,A^?) = 2.8 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Cs⁺) = 4.7 ± 0.1. Finally, by using quantum–mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1·Cs⁺ was derived.     

Synergistic extraction of some univalent cations into nitrobenzene by using cesium dicarbollylcobaltate and dibenzo-30-crown-10

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺(aq) + 1·Cs⁺(nb) ? 1·M⁺(nb) + Cs⁺(aq) taking place in the two-phase water–nitrobenzene system (M⁺ = Li⁺, Na⁺, H⁺, NH₄ ⁺, Ag⁺, K⁺, Rb⁺, Tl⁺; 1 = dibenzo-30-crown-10; aq = aqueous phase, nb = nitrobenzene phase) were determined. Furthermore, the stability constants of the 1·M⁺ complexes in water-saturated nitrobenzene were calculated; they were found to increase in the series of Cs⁺ < H⁺, Ag⁺ < NH₄ ⁺ < Na⁺ < Rb⁺ < Li⁺ < K⁺, Tl⁺.     

Complexation of the cesium cation with 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs⁺(aq) + I^?(aq) + 1(nb) ? 1·Cs⁺(nb) + I^?(nb) taking place in the two–phase water–nitrobenzene system (1 = 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (1·Cs⁺, I^?) = 2.9 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β_nb (1·Cs⁺) = 8.8 ± 0.1. Finally, by using quantum–mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1·Cs⁺ was derived.     

On the complexation of some univalent cations with 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6 in nitrobenzene saturated with water

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺ (aq) + 1·Cs⁺ (nb) ? 1·M⁺ (nb) + Cs⁺ (aq) taking place in the two-phase water–nitrobenzene system (M⁺ = Ag⁺, K⁺, Rb⁺, Tl⁺; 1 = 1,3-alternate-25,27-bis(1-octyloxy)calix[4]arene-crown-6; aq is aqueous phase, nb is nitrobenzene phase) were determined. Moreover, the stability constants of the 1·M⁺ complexes in water-saturated nitrobenzene were calculated; they were found to increase in the series of K⁺ < Rb⁺ < Ag⁺ < Tl⁺.     

Interactions of some protonated α-amino acid methyl esters with hexaethyl p-tert-butylcalix[6]arene hexaacetate in nitrobenzene saturated with water

The exchange extraction constants corresponding to the general equilibrium C⁺(aq) + 1·Cs⁺(nb) ? 1·C⁺ (nb) + Cs⁺(aq) occurring in the two-phase water–nitrobenzene system (C⁺ = protonated α-amino acid methyl ester, 1 = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated on the basis of extraction experiments and γ-activity measurements. Further, the stability constants of the 1·C⁺ cationic complex species in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: protonated l-tryptophan methyl ester < protonated l-phenylalanine methyl ester < protonated l-leucine methyl ester < protonated l-methionine methyl ester < protonated l-valine methyl ester.     

Complexation of some univalent organic cations with hexaethyl p-tert-butylcalix[6]arene hexaacetate in nitrobenzene saturated water

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium C⁺(aq) + 1·Cs⁺(nb) ?1·C⁺ (nb) + Cs⁺(aq) taking place in the two–phase water–nitrobenzene system (C⁺ = methylammonium, ethylammonium, propylammonium, ethanolammonium, diethanolammonium, triethanolammonium, protonated tyramine, protonated dopamine, protonated DL–noradrenaline; 1 = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the 1·C⁺ complex species in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: protonated tyramine < protonated dopamine < triethanolammonium < diethanolammonium < protonated DL-noradrenaline < propylammonium < ethanolammonium < ethylammonium < methylammonium.     

Experimental and theoretical study on the complexation of Ca2+ with beauvericin

From extraction experiments and γ-activity measurements, the exchange extraction constant corresponding to the equilibrium Ca²⁺(aq) + 1·Sr²⁺(nb) ? 1·Ca²⁺(nb) + Sr²⁺(aq) taking place in the two-phase water–nitrobenzene system (1 = beauvericin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex(Ca²⁺, 1·Sr²⁺) = 1.1 ± 0.1. Further, the stability constant of the 1·Ca²⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb(1·Ca²⁺) = 10.1 ± 0.2. Finally, by using quantum mechanical density functional level of theory calculations, the most probable structures of the non-hydrated 1·Ca²⁺ and hydrated 1·Ca²⁺·H₂O complex species were predicted.     

Extraction and theoretical study on the complexation of the strontium cation with beauvericin

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Sr²⁺(aq) + 2A^?(aq) +1(nb) ? 1·Sr²⁺(nb) + 2A^?(nb) taking place in the two-phase water–nitrobenzene system (A^? = picrate, 1 = beauvericin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex(1·Sr²⁺,2A^?) = ?0.6 ± 0.1. Further, the stability constant of the 1·Sr²⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb(1·Sr²⁺) = 8.5 ± 0.1. Finally, by using quantum-mechanical DFT calculations, the most probable structure of the resulting cationic complex 1·Sr²⁺ was derived.     

Complexation of some univalent organic cations with benzo-18-crown-6 in nitrobenzene saturated with water

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium C⁺(aq) + 1·Na⁺(nb) ? 1·C⁺(nb) + Na⁺(aq) taking place in the two-phase water–nitrobenzene system (C⁺ = univalent organic cation, 1 = benzo-18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants of the 1·C⁺ complex species in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: protonated tyramine, protonated l-valine methyl ester < protonated dopamine < protonated serotonin < methylammonium < protonated hexamethylenetetramine < ethanolammonium < protonated dl-noradrenaline.     

Experimental and DFT study on the complexation of Ba2+ with beauvericin

From extraction experiments and γ-activity measurements, the exchange extraction constant corresponding to the equilibrium Ba²⁺(aq) + 1·Sr²⁺(nb) ?1·Ba²⁺(nb) + Sr²⁺(aq) taking place in the two-phase water–nitrobenzene system (1 = beauvericin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (Ba²⁺, 1·Sr²⁺) = 1.2 ± 0.1. Further, the stability constant of the beauvericin–barium complex (abbrev. 1·Ba²⁺) in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Ba²⁺) = 9.5 ± 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the 1·Ba²⁺ complex species was predicted.     

Extraction and theoretical study on complexation of the strontium cation with antamanide

By using extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Sr²⁺(aq) + 2A^?(aq) + 1(nb) ? 1·Sr²⁺(nb) + 2A^?(nb) occurring in the two-phase water–nitrobenzene system (A^? = picrate, 1 = antamanide; aq = aqueous phase, nb = nitrobenzene phase) was determined as log K _ex (1·Sr²⁺, 2A^?) = ?0.3 ± 0.1. Further, the stability constant of the 1·Sr²⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β _nb (1·Sr²⁺) = 8.8 ± 0.1. Finally, applying quantum mechanical density functional level of theory calculations, the most probable structure of the cationic complex species 1·Sr²⁺ was derived. In the resulting complex, the “central” cation Sr²⁺ is bound by six bond interactions to the corresponding six oxygen atoms of the parent ligand 1. The interaction energy of the considered 1·Sr²⁺ complex was found to be ?1,114.9 kJ/mol, confirming the formation of this cationic species as well.     

On the complexation of some univalent cations with beauvericin in nitrobenzene saturated with water

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺(aq)?+?1·Cs⁺(nb) ? 1·M⁺(nb)?+?Cs⁺(aq) taking place in the two-phase water–nitrobenzene system (M⁺?=?Li⁺, Na⁺, K⁺, Rb⁺, H₃O⁺, NH₄ ⁺, Tl⁺; 1?=?beauvericin; aq?=?aqueous phase, nb?=?nitrobenzene phase) were determined. Moreover, the stability constants of the 1·M⁺ complexes in water-saturated nitrobenzene were calculated; they were found to increase in the series of Rb^+?<?Na⁺, H₃O^+?<?Tl^+?<?NH ₄ ^+? <?K^+?<?Li⁺.     

Solvent extraction of europium trifluoromethanesulfonate into nitrobenzene by using three electroneutral receptors

From extraction experiments and $ \gamma $ -activity measurements, the extraction constants corresponding to the general equilibrium Eu³⁺(aq) + 3 A^?(aq) + L(nb) $ \Leftrightarrow $ EuL³⁺(nb) + 3A^?(nb) taking place in the two-phase water–nitrobenzene system ( $ {\text{A}}^{ - } = {\text{CF}}_{ 3} {\text{SO}}_{3}^{ - } $ ; L = electroneutral receptors denoted by 1, 2, and 3 – see Scheme 1; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Further, the stability constants of the EuL³⁺ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the series of 3 < 2 < 1.

Hydrogen Bonding and Solvent Effects on Complexation of Alkali Metal Cations by Lower Rim Calix[4]arene Tetra(O-[N-acetyl-D-phenylglycine methyl ester]) Derivative

Complexation of alkali metal cations with 5,11,17,23-tetra-tert-butyl-26,28,25,27-tetrakis(O-methyl-D-α-phenylglycylcarbonylmethoxy)calix[4]arene (L) was studied by means of spectrophotometric, conductometric and potentiometric titrations at 25 °C. The solvent effect on the binding ability of L was examined by using two solvents with different affinities for hydrogen bonding, viz. methanol and acetonitrile. Despite the presence of intramolecular NH···O=C hydrogen bonds in L, which need to be disrupted to allow metal ion binding, this calix[4]arene amino acid derivative was shown to be an efficient binder for smaller Li⁺ and Na⁺ cations in acetonitrile (lg K _LiL  > 5, lg K _NaL  = 7.66), moderately efficient for K⁺ (lg K _KL  = 4.62), whereas larger Rb⁺ and Cs⁺ did not fit in its hydrophilic cavity. The complex stabilities in methanol were significantly lower (lg K _NaL  =  4.45, lg K _KL  = 2.48). That could be explained by different solvation of the cations and by competition between the cations and methanol molecules (via hydrogen bonds) for amide carbonyl oxygens. The influence of cation solvation on complex stability was most pronounced in the case of Li⁺ for which, contrary to the quite stable LiL ⁺ complex in acetonitrile, no complexation was observed in methanol under the conditions used.     

Synergistic extraction of some univalent cations into nitrobenzene by using cesium dicarbollylcobaltate and calix[4]arene-bis(t-octylbenzo-18-crown-6)

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺ (aq) + CsL⁺ (nb) ? ML⁺ (nb) + Cs⁺ (aq) taking place in the two–phase water–nitrobenzene system (M⁺ = K⁺, Rb⁺, $ {\text{NH}}_{4}^{ + } $ , Ag⁺, Tl⁺; L = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML⁺ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: $ {\text{NH}}_{4}^{ + } $  < K⁺ < Ag⁺ < Rb⁺ < Tl⁺.     

Synergistic extraction of some divalent metal cations into nitrobenzene by using strontium dicarbollylcobaltate and electroneutral macrocyclic lactam receptor

From extraction experiments and $ \gamma $ -activity measurements, the exchange extraction constants corresponding to the general equilibrium M²⁺(aq) + 1·Sr²⁺(nb) $ \Leftrightarrow $ 1·M²⁺(nb) + Sr²⁺(aq) taking place in the two-phase water–nitrobenzene system (M²⁺ = Mg²⁺, Ca²⁺, Ba²⁺, Pb²⁺, Cu²⁺, Zn²⁺, Cd²⁺, $ {\hbox{UO}}_{2}^{2 + } $ , Mn²⁺, Co²⁺, Ni²⁺; 1 = macrocyclic lactam receptor–see Scheme 1; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants of the 1·M²⁺ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: Mg²⁺ < Co²⁺ < Cu²⁺, Mn²⁺, Ni²⁺ < Cd²⁺ < Ca²⁺ < Ba²⁺, Zn²⁺ < Pb²⁺ <  $ {\hbox{UO}}_{2}^{2 + } $ .

Lower rim substituted p-tert-butyl calix[4]arene; Part 14. Synthesis, structures and binding studies of calix[4]arene thioamides

A number of p-tert-butylcalix[4]arene thioamides were synthesized and characterized by ¹H-NMR and elemental analysis. Compounds 1–5 are O-substituted derivatives with –CH₂–C(=S)–N–X groups, where NX = morpholidyl, NEt₂, NHC₂H₄Ph, NHCH₂Ph and NHEt, respectively. The X-ray structures of the ligands 1, 3, 5 and of the complex 3·Pb(ClO₄)₂, (compound 6), are presented and their slightly distorted cone conformation is established. The influence of the nature of the thioamide functions (secondary or tertiary) on the extractability of some selected metal cations was investigated. Whereas all these calixarenes show the highest extraction level for Ag⁺, tertiary thioamides are more efficient extractants for Pb²⁺ than secondary thioamides.