Competitive cesium-133 NMR spectroscopic study of complexation of different metal ions with dibenzo-21-crown-7 in acetonitrile-dimethylsulfoxide and nitromethane-dimethylsulfoxide mixtures

133Cs Nuclear Magnetic Resonance Relaxometry as a Probe of the Mobility of Cesium Cations Confined within Dense Clay Sediments

“…In that framework, NMR dynamical measurements are ideal investigation tools thanks to their complete selectivity. As an example, a large variety of 133 Cs NMR investigations were already performed to characterize the structural and dynamical properties of cesium cation in the presence of adsorbing agents like crown-ethers − or various interfacial material, including polymers, biological macromolecules, , micelles, , zeolites, − and clays. − Unfortunately, in the case of dense clay sediments like those used for waste storing, it becomes impossible to extract dynamical information on the cesium mobility by using NMR PGSE because of the fast relaxation of the transverse magnetization precluding the use of pulsed field gradient. Furthermore, 133 Cs a priori appears as an inappropriate probe for using the field-cycling NMR relaxometer − because of the small longitudinal relaxation rate measured in dilute aqueous solution ( R 1 = 7.5 × 10 –2 s –1 ) (see the Appendix).…”

NMR study of the stoichiometry and stability of complexation reaction between Mg2+, Ca2+, Sr2+ and Ba2+ ions and 60-crown-20 in binary acetonitrile solvent mixtures

“…From the data in Table 1, it is obvious that the stability of all 60C20 complexes increased in the order of acetonitrile-D 2 O \ acetonitrile \ acetonitrile-nitromethane. It is well known that the Gutmann donors number of solvent [23] is an important factor in complexation reactions [17][18][19]. It should be noted that acetonitrile and nitromethane possess similar dielectric constants (i.e., e AN = 37.5, e NM = 35.6), but have quite different donors number (i.e., DN AN = 14.1 and DN NM = 2.7) 23 .…”

“…Various techniques have been used to study the complexation of a range of ligands with different cations in a variety of nonaqueous and mixed solvents [14][15][16]. Among the spectroscopic and electrochemical methods used for the study of metal ion-crown ether complexes, NMR spectroscopy has been found to act as a very sensitive technique for studying the changes in the immediate chemical environment of metal ions in solutions [17,18]. To the best of our knowledge there are no report on the complexation reaction between 60-crown-20 (60C20) and metal ions, we attempted to study the complexation reaction of 60C20 with Mg 2?…”