Sadaya Kitazawa

Lithium-selective polymeric membrane electrodes based on dodecylmethyl-14-crown-4

Lithium-selective electrodes were prepared with polymeric membranes containing dodecyl-methyl-14-crown-4 as a neutral carrier. The effects of the crown ether content in the membrane and the type of membrane solvent on the electrode properties were investigated. Typical Li+-selective electrodes showed a linear Nernstian response in the activity range 1 × 10–5–1 M LiCl, preferring lithium to sodium and hydronium ions by factors of 150 and 6800, respectively. Addition of trioctylphosphine oxide to the membrane enhanced the lithium selectivity over sodium in the electrode, although it had adverse effects on the lithium selectivity over hydronium ion and the detection limit. The determination of lithium in artificial serum samples was also attempted with these lithium-selective electrodes.

Novel lithium-selective ionophores bearing an easily ionizable moiety

Lipophilic 14-crown-4 derivatives incorporating nitrophenol substituent are excellent lithium ionophores for proton-driven cation transport, in which extremely high selectivity ratios of lithium over sodium are realized.

Synthesis and selectivity for lithium of lipophilic 14-crown-4 derivatives bearing bulky substituents or an additional binding site in the side arm

Two types of 6,6-disubstituted 14-crown-4 (1,4,8,11-tetraoxacyclotetradecane) derivatives have been synthesized in the hope of improving on the selectivity of the parent macrocycle for Li+, especially against Na+ and K+. Selectivity enhancement was expected to result from incorporation of bulky substituents which suppress the formation of stable sandwich-type complexes with Na+ and K+, and from the attachment of an additional binding site possessing affinity for Li+. Studies of the electrochemical selectivity of membranes containing the crown ethers showed that selectivities for Li+ with respect to Na+ and K+ are augmented in 6,6-dibenzyl- and 6-diethylcarbamoylmethyl-6-dodecyl-14-crown-4, (6) and (18), as compared with the 6-dodecyl-6-methyl derivative (2).

Cation-binding properties of poly- and bis(benzo-21-crown-7)derivatives

ZusammenfassungPoly- und Bis-kronenether mit dem relativ großen Kronenetherring Benzo-21-krone-7 wurden dargestellt und ihr Bindungsvermögen für Alkaliionen wurde durch Lösungsextraktion und auch konduktometrisch untersucht. Es ergab sich, daß das Bindungsvermögen in der Reihenfolge Cs+>Rb+>K+>Na+ abnimmt. Diese Substanzen können Alkaliionen wirksamer extrahieren als die entsprechenden Monomeren Analogen. Das Bindungsvermögen für einige organische Kationen, wie z.B. Alkylammonium und Guanidinium, wurde ebenfalls untersucht.SummaryPoly- and bis(crown ether)s which contain the relatively large crown ether ring of benzo-21-crown-7 were synthesized, and their cation-binding properties for alkali metal cations were elucidated by solvent extraction and also conductometrically. The cation-binding ability was found to decrease in the order Cs+>Rb+>K+>Na+. They can extract alkali metal cations more efficiently than the corresponding monomeric analogue. The binding behaviour for some organic cations such as alkyl ammonium and guanidinium is also described.

Enhanced calcium ion selectivity of a macrocyclic polyether-amide with two polyether rings

The macrocyclic polyether -amide (1) is shown to be mere selective than its corresponding monocyclic analogue (4) for the Ca2+ ion; the potentiometric selectivity for Ca2+ relative to Mg2+ is improved by more than one order of magnitude.