Stabilization of crown ether containing supported liquid membranes

Abstract

wiped with Kimwipe between scans. A Ag/Agl reference electrode was made by dipping a silver wire coated with Agl by anodic deposition into a saturated solution of Et4N+I" in DMSO and sealed by a VYCOR membrane.An amount of the neutral compound sufficient to make 5 mL of 3.0 mM solution was weighed into the electrochemical cell and placed on the cell holder. Tetraethylammonium tetrafluoroborate (electrometric grade from Southwestern Analytical Chemicals Inc., dried under vacuum at 70 °C for 48 h, 0.108 mg) was placed in the cell and 5 mL of purified DMSO was added. Pure argon was bubbled through the solution constantly except while recording the scan, at which time the solution was blanketed with argon. About 0.3 equiv of CH3SOCH2K (150-200 mM solution) was added in aliquots and the cyclic voltammogram recorded after each addition. In the case of thiazolium salts, the neutral solution was scanned under argon to ensure that the oxidation of the counterion would not cause interference. Cyclic voltammograms were recorded at a scan rate of 100 mV/s on a Houston 100 X-Y recorder. The ferrocenium/ferrocene redox couple (0.875 mV vs Ag/Agl) was used as a standard. The redox couple of ferrocenium/ferrocene was checked against the reference electrode before and after the measurements.

Kinetic Study of Charge Transfer Complexes of Iodine With Some Crown Ethers in Nonaqueous Solvents

“…During the past two decades, a growing interest has been focused on the complexing ability of these macrocyclic ligands as electron-pair molecules towards neutral and, especially, molecular iodine [9][10][11][12][13]. Iodine has been found to form with many compounds charge transfer complexes whose properties have been thoroughly studied [14][15][16][17][18]. Various physico-chemical techniques such as: spectrophotometry [19,20], NMR spectrometry [21], polarography [22,23], potentiometry [24] and conductometry [25][26][27] have been used to study the complex formation between macrocyclic polyethers (crown ethers) and various metal cations in solutions.…”

Conductometric study of complexation reaction between 15-crown-5 and Cr3+, Mn2+ and Zn2+ metal cations in pure and binary mixed organic solvents

“…Over the years, these heteromacrocyclic ligands have been used for the construction of new materials and devices, such as: organic synthesis [6], in construction of ion-selective electrodes [7,8], separation of metal cations [9][10][11][12], as solid phase in chromatography columns [13][14][15][16], in the design of fiber optic chemical sensors [17], in ion exchange membranes [18], recognition of isomers [19] and also in chemical analysis [20,21]. Most of the applications of the crown compounds are based on their complexing ability to the metal cations.…”

Development of Chemically Bonded Crown Ether Stationary Phases in Capillary Ion Chromatography

“…Macrocyclic ligands such as crown ethers and cryptands are highly selective in binding metal and other cations and have been employed in a variety of separation technologies, including solvent extraction, membranes and chromatography based on the size-fit theory as one of the important factors overseeing the complexation selectivity [2][3][4][5][6]. Crown ether complexation with simple metal cations has been most extensively studied and a number of reliable physicochemical data are available, thus allowing us to quantitatively discuss the thermodynamic and structural aspects of crown ether complexes [7][8].…”