Investigation of carrier-mediated anion co-transport through organic membranes by use of competitive transport experiments

Fricke, Tom; Hamann, J.; Bahadir, Müfit; König, Burkhard

doi:10.1007/s00216-002-1394-8

Cited by 14 publications

(2 citation statements)

References 20 publications

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“…[33,34] In liquid/liquid extraction and transport, a (salen)Mn III -type complex and a neutral tetraaza-macrocyclic Ni II complex were observed to have enhanced fluoride selectivity. [35] In transport using these respective carriers, the following orders were found: -. [36] The use of Lewis acid sites for selective anion binding has been under investigation for development of potentiometric anion sensors, providing insight into anion-binding selectivity in ion partitioning.…”

Section: Single-point Interactionsmentioning

confidence: 99%

Anion Separation with Metal–Organic Frameworks

2007

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The application of metal-organic frameworks (MOFs) to anion separations with a special emphasis on anion selectivity is reviewed. The coordination frameworks are classified on the basis of the main interactions to the included anion, from weak and non-specific van der Waals forces to more specific interactions such as coordination to Lewis acid metal centers or hydrogen bonding. The importance of anion solvation phenomena to the observed anion selectivities is highlighted, and strategies for reversing the Hofmeister bias that favors large, less hydrophilic anions, and for obtaining peak

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Section: Single-point Interactionsmentioning

confidence: 99%

Anion Separation with Metal–Organic Frameworks

2007

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“…The apparent selectivity in favor of charge-diffuse anions has been referred to as Hofmeister bias , by reference to the early ordering of anions noted by Hofmeister in experiments on salting-out phenomena. It has proven very difficult to overcome the Hofmeister bias in liquid−liquid systems, , and examples of true deviations from this expected ordering by use of hydrogen-bond-donor receptors 12c, and solvation effects 10a are rare. More generally, it is possible to attenuate the steepness of the bias by use of solvation effects 11 or hydrogen-bond receptors …”

Section: Introductionmentioning

confidence: 99%

Anion Partitioning and Ion-Pairing Behavior of Anions in the Extraction of Cesium Salts by 4,5‘ ‘-Bis(tert-octylbenzo)dibenzo-24-crown-8 in 1,2-Dichloroethane

et al. 2006

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A systematic study of anion partitioning and ion pairing was performed for an extraction of individual cesium salts into 1,2-dichloroethane (1,2-DCE) using 4,5' '-bis(tert-octylbenzo)dibenzo-24-crown-8 as the cesium receptor. Equilibrium constants corresponding to the extraction of ion pairs and dissociated ions, formation of the 1:1 cesium/crown complex (confirmed by electrospray mass spectrometry), and dissociation of the ion pairs in water-saturated 1,2-DCE at 25 degrees C were obtained from equilibrium modeling using the SXLSQI program. The standard Gibbs energy of partitioning between water and water-saturated 1,2-DCE was determined for picrate, permanganate, trifluoromethanesulfonate, methanesulfonate, trifluoroacetate, and acetate anions. The dissociation of the organic-phase complex ion pair [Cs(4,4' '-bis(tert-octylbenzo)dibenzo-24-crown-8]+NO3- observed in the extraction experiments was shown to be consistent with the dissociation constant determined independently by conductance measurements. As attributed to the large effective radius of the complex cation, the evident anion discrimination due to ion pairing in the 1,2-DCE phase was relatively small, by comparison only a tenth of the discrimination exhibited by the anion partitioning. Only chloride and picrate exhibit evidence for significantly greater-than-expected ion-pairing tendency. These results provide insight into the inclusion properties of the clefts formed by opposing arene rings of the crown ether upon encapsulation of the Cs+ ion, whose weak anion recognition likely reflects the preferential inclusion of 1,2-DCE molecules in the clefts. Observed anion extraction selectivity in this system, which may be ascribed predominantly to solvent-induced Hofmeister bias selectivity toward large charge-diffuse anions, was nearly the same whether cesium salts were extracted as dissociated ions or ion pairs.

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Where is the Anion Extraction Going?

Gloe¹,

Stephan

Grotjahn

2003

Chem Eng & Technol

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Reactive extraction processes represent efficient and smart technologies for separation and concentration of metal ions in solution, which are frequently used in industry. Despite the importance of anions in biology, medicine, environment and industry, practical examples of anion extraction are relatively limited compared to metal ion separation. Anion extraction processes are mainly based on the nonspecific ion pair formation with hydrophobic ammonium cations. In this case the phase transfer of anions is dominated by their lipophilicity. The reasons for this situation are closely connected with the specific features of anions in contrast to cations. Novel approaches for specific binding and selective transport of anionic components are based both on the better understanding of the biological role of anions and on the possibilities of supramolecular chemistry to create receptor architectures with complementary binding modes for anions. In the given review the authors discuss present research tendencies and application possibilities of new extractant types for separation and concentration of anionic species in solution.

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Investigation of carrier-mediated anion co-transport through organic membranes by use of competitive transport experiments

Cited by 14 publications

References 20 publications

Anion Separation with Metal–Organic Frameworks

Anion Separation with Metal–Organic Frameworks

Anion Partitioning and Ion-Pairing Behavior of Anions in the Extraction of Cesium Salts by 4,5‘ ‘-Bis(tert-octylbenzo)dibenzo-24-crown-8 in 1,2-Dichloroethane

Where is the Anion Extraction Going?

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