Arene Hexaacetate Research Articles

Interaction of the cesium cation with hexaethyl calix[6]arene hexaacetate: Extraction and DFT study

On the basis of extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Cs+(aq)+A−(aq)+1(nb)⇄1·Cs+(nb)+A−(nb) occurring in the two-phase water–nitrobenzene system (1=hexaethyl calix[6]arene hexaacetate; A−=picrate, aq=aqueous phase, nb=nitrobenzene phase) was evaluated as log Kex (1·Cs+, A−)=6.8±0.1. Further, the very high stability constant of the 1·Cs+ complex in nitrobenzene saturated with water was calculated for a temperature of 25°C: log βnb (1·Cs+)=8.7±0.1. Finally, applying quantum mechanical DFT calculations, the most probable structure of the proven 1·Cs+ cationic complex species was derived. In the resulting complex, the “central” cation Cs+ is bound by six very strong bonding interactions to the corresponding six oxygen atoms of the parent ligand 1. The interaction energy of the considered 1·Cs+ complex was found to be −308.0kJ/mol, confirming the formation of this complex as well.

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

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

Synergistic extraction of some divalent cations into nitrobenzene by using strontium dicarbollylcobaltate and hexaethyl p- tert-butylcalix[6]arene hexaacetate

Synergistic extraction of some divalent cations into nitrobenzene by using strontium dicarbollylcobaltate and hexaethyl p- tert-butylcalix[6]arene hexaacetate

Synergistic extraction of some univalent cations into nitrobenzene by using sodium dicarbollylcobaltate and hexaethyl p-tert-butylcalix[6]arene hexaacetate

From extraction experiments and c-activity measurements, the exchange extraction constants corresponding to the general equilibrium M (aq) ? NaL (nb) , ML (nb) ? Na (aq) taking place in the twophase water–nitrobenzene system (M = H3O , NH4 þ, Ag, Tl; L = hexaethyl p-tert-butylcalix[6]arene hexaacetate; 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 order: Agþ \ NH4 \ H3O \ Naþ \ Tlþ:

Solvent extraction of some divalent metal cations into nitrobenzene by using a synergistic mixture of strontium dicarbollylcobaltate and hexaethyl calix[6]arene hexaacetate

From extraction experiments and c-activity measurements, the exchange extraction constants corresponding to the general equilibrium M2þðaqÞ þ SrL2þðnbÞ , ML2þðnbÞ þ Sr2þðaqÞ taking place in the two-phase water–nitrobenzene system (M = Ca, Ba, Pb, Cd; L = hexaethyl calix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants of the ML complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following order: Cd \ Ca \ Sr \ Pb \ Ba.

Extraction of K+, Rb+ and Tl+ from Water into Nitrobenzene by Using Cesium Dicarbollylcobaltate in the Presence of Hexaethyl Calix[6]arene Hexaacetate

Abstract 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+, Tl+; L = hexaethyl calix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Further, the stability constants of the ML+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order K+&lt; Rb+&lt; Tl+.

Stability constants of complexes of Li+, H3O+, NH 4 + and Ag+ with hexaethyl calix[6]arene hexaacetate in nitrobenzene saturated with water

From extraction experiments and -activity measurements, the exchange extraction constants corresponding to the general equilibrium M+(aq)+NaL+(nb) ML+(nb)+Na+(aq) taking place in the two–phase water–nitrobenzene system (M+ = Li+, H3O, NH4, Ag+; L = hexaethyl calix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were determined. Furthermore, the stability constants of the ML+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order H3O<NH4<Li<Ag.

Contribution to the thermodynamics of complexes of alkali metal cations with hexaethyl p-tert-butylcalix[6]arene hexaacetate in the water—nitrobenzene extraction system

From extraction experiments and -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+ = Li+, Na+, K+, Rb+; L = hexaethyl p-tertbutylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were determined. Moreover, the stability constants of the ML+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Rb+<Cs+<K+<Na+<Li+.

A Combined Experimental and Theoretical Study on the Complexation of H3O+ with Hexaethyl Calix[6]arene Hexaacetate

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium H3O+(aq) + 1•Na+(nb) ⇔ 1•H3O+(nb) + Na+(aq) taking place in the two-phase water–nitrobenzene system (1 = hexaethyl calix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K ex(H3O+,1•Na+) = 0.0± 0.1. Further, the stability constant of the 1•H3O+ complex in water saturated nitrobenzene was calculated for a temperature of 25°C as log βnb(1•H3O+) = 4.8 ± 0.1. By using quantum mechanical DFT calculations, the most probable structure of the 1•H3O+ complex species was predicted. In this complex, the hydroxonium ion H3O+ is bound partly to three carbonyl oxygen atoms by strong hydrogen bonds and partly to three alternate phenoxy oxygens by somewhat weaker hydrogen bonds.

Extraction and DFT study on the complexation of H 3O + with hexaethyl p- tert-butylcalix[6]arene hexaacetate

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium H 3O +(aq) + 1· Na +(nb) ⇆ 1·H 3O +(nb) + Na +(aq) taking place in the two-phase water–nitrobenzene system ( 1 = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K ex (H 3O +, 1·Na +) = −0.6 ± 0.1. Further, the stability constant of the 1·H 3O + complex in water saturated nitrobenzene was calculated for a temperature of 25 °C as log β nb ( 1·H 3O +) = 6.8 ± 0. 2. By using quantum mechanical DFT calculations, the most probable structure of the 1·H 3O + complex species was predicted. In this complex, the hydroxonium ion H 3O + is bound partly to three carbonyl oxygen atoms by strong hydrogen bonds and partly to three alternate phenoxy oxygens by somewhat weaker hydrogen bonds.

Synthesis and Cation-Binding Properties of Novel p-Isopropenylcalix[n]arenes and Their Acetylated Derivatives

A novel two-step method was developed to prepare individual p-isopropenylcalix[n]arenes [n=4, 6, 8]. In the first step, linear phenolic oligomers were prepared in a basic medium from p-isopropenylphenol and paraformaldehyde. The second step, cyclization of the linear oligomers was carried out at higher temperatures. Ethylene glycol was used as medium, and sodium tetraborate-decahydrate as the catalyst. O-Acetylated derivatives were obtained by acetylation of the phenolic hydroxyl groups of p-isopropenylcalix[n]arenes [n=4, 6, 8]. The p-isopropenyl-calix[n]arenes and their acetylated derivatives were characterized by IR, 1H NMR and UV spectroscopy, and elemental analysis. Their ability to extract metal cations from aqueous solutions was evaluated via metal picrate extraction experiments. A parallel investigation of the cation-binding ability of the p-tert-butylcalix[n]arenes [n=4, 6, 8] and their acetylated derivatives was also performed. The p-isopropenylcalix[6]arene hexaacetate is the most effective extracting agent for metal picrates, and shows strong affinity towards Rb cation.