Thermodynamic and kinetic data for macrocycle interactions with cations and anions

Izatt, Reed M.; Pawlak, Krystyna; Bradshaw, Jerald S.; Bruening, Ronald L.

doi:10.1021/cr00008a003

Cited by 1,948 publications

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“…Studies of crown ethers complexation in different solvents show that the thermodynamic and kinetic parameters and even the mechanism of the complexation processes are affected by the nature and composition of the solvent system [5,6]. Crown ethers are macrocyclic ethers known for their ability to form stable and selective inclusion complexes with many metal ions, including alkali and alkaline earth metal cations [7]. The stability of these complexes appears to be related to the macrocycles , cavity sizes; It is at maximum when the cavity diameter matches the ionic size [8].…”

Section: Introductionmentioning

confidence: 99%

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

Alizadeh

Roomiani

2012

J. Chil. Chem. Soc.

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Charge-transfer complexation of iodine with 15-crown-5(15C5), dicyclohexyl-18-crown-6 (DC18C6), benzo-18-crown-6 (B18C6) and dibenzo-24-crown-8 (DB24C8) has been studied in chloroform (CHCl 3 ), Dichloromethane (DCM) and 1,2-dichloroethane (1,2-DCE) solutions at different time. The results indicated immediate formation of an electron donor-electron acceptor complex; which is followed by two relatively slow consecutive reactions. The pseudo-first-order rate constants for the formation of the ionic intermediate and the final product have been evaluated at 25 °C. The rate of formation of product has been measured as a function of time in different halocarbone solvents. The pseudo first order rate constants were evaluated from the absorbance-time data and found to vary in the order of 1,2-DCE >DCM >CHCl 3 .

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Section: Introductionmentioning

confidence: 99%

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

Alizadeh

Roomiani

2012

J. Chil. Chem. Soc.

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“…1 The complexation between alkali metal ions and macrocyclic polyethers, polyamines or polyetheramines has been extensively studied by means of various methods in many solvent systems. 2,3 The fitness of the cavity size of a macrocyclic compound is an important factor for determining the stability of an alkali metal complex. 4 Solvent effects in the complexation of cryptand [2.2] (1,10-diaza-18-crown-6) with Li + have indicated that the stability of the complex varies inversely with the donicity of the solvent.…”

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confidence: 99%

Interaction between Monoaza-, Diaza-, or Polyazacrown Ethers and Alkali Metal Ions in Acetonitrile by Polarography

et al. 2000

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Crown-type compounds are of general relevance as synthetic model substances for studying physiological ion-transport processed in biological membranes, for investigating receptor and enzyme interactions as well as for the salt balance and for metabolic processes of living organisms. 1 The complexation between alkali metal ions and macrocyclic polyethers, polyamines or polyetheramines has been extensively studied by means of various methods in many solvent systems. 2,3 The fitness of the cavity size of a macrocyclic compound is an important factor for determining the stability of an alkali metal complex. 4 Solvent effects in the complexation of cryptand [2.2] (1,10-diaza-18-crown-6) with Li + have indicated that the stability of the complex varies inversely with the donicity of the solvent.5 However, little attention may have been paid to the increase in the basicity of coordinating atoms by substitution of the oxygen atoms with NH groups in crown ethers.In the present study, the formation constants of alkali metal complexes with monoaza-, diaza-, and polyazacrown ethers were obtained by means of mainly d.c. polarography; differential pulse polarography on DME and cyclic voltammetry on HMDE were additionally employed.The mercurydissolution processes of the macrocyclic compounds were clarified during the course of examining alkali metal ion complexation. The variation in the formation constants is discussed from the viewpoint of not only cavity size, but also the interaction between the Lewis acids and bases. The main purpose of the present study was to investigate the effects of the number of substitution of the oxygen atoms with NH groups in the crown ethers on the stabilities of the Li + and Na + complexs of 12-crown-4, 15-crown-5, and 18-crown-6.We have developed a new analytical method in d.c. polarography for obtaining the complex formation constant between cations and an anion which induces the mercurydissolution wave on DME. 6 This method was first successfully applied to the Li + -CH3COO-system in acetonitrile. The formation constants of a "reverse coordinated" species, CH3COO -(M + )2 (M + = Li + or Na + ), 6 and later that of (Li + )2Cl -7were obtained. Since then, we have revealed that the Li + ion operates an unexpectedly strong coordination ability in protophobic aprotic solvents. 8,9 Our method was found to be very useful for examining complex formation between alkali metal ions and macrocyclic polyamines (cyclam, tetramethylcyclam) 10,11 as well as acyclic polyamines (ethylenediamine, trien, tetren). 12The complex formation of cryptand[2.2] and its sulfur derivative (ATCO: 1,10-diaza-4,7,13,16-tetrathiacyclooctadecane) with alkali metal or alkaline earth metal ions in acetonitrile has been examined. 13 In principle, "the mercury-dissolution method" utilizes the The complex formation constants between alkali metal ions and monoaza-or diazacrown ethers (L) in acetonitrile have been obtained by the analytical method of d.c. polarography, in which a positive shift in E1/2 of the mercury-dissolution w...

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“…However, mutual separation of the alkaline earth metal ions is difficult to obtain with strongly acidic cation exchange resins. On the other hand, it is well known that crown ethers and diazapolyoxabicyclic ligands such as cryptand [2.2.1] and cryptand [2.2.2] exhibit a significant selectivity for alkali and alkaline earth metal ions [1][2][3]. Their selectivity for metal ions depends largely on the size of the cavity, therefore, one can choose an appropriate cryptand according to requirements.…”

Section: Introductionmentioning

confidence: 99%

Separation of Alkaline Earth Metal Ions with a Strongly Acidic Cation Exchange Resin Using the Diazapolyoxabicyclic Ligand as an Ion Size Selective Masking Reagent

Turubou

Umetani

Komatsu

2012

SERDJ

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Thermodynamic and kinetic data for macrocycle interactions with cations and anions

Cited by 1,948 publications

References 0 publications

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

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

Interaction between Monoaza-, Diaza-, or Polyazacrown Ethers and Alkali Metal Ions in Acetonitrile by Polarography

Separation of Alkaline Earth Metal Ions with a Strongly Acidic Cation Exchange Resin Using the Diazapolyoxabicyclic Ligand as an Ion Size Selective Masking Reagent

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