A PGSE diffusion and electrophoretic NMR study of Cs+ and Na+ dynamics in aqueous crown ether systems
2007 (English)In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 45, no 2, 152-156 p.Article in journal (Refereed) Published
Multinuclear pulsed gradient spin-echo (PGSE) NMR diffusion and linewidth measurements were used to probe binding and transport in aqueous Na+-15-crown-5, Na+-18-crown-6, Cs+-15-crown-5 and Cs+-18-crown-6 systems. Since direct PGSE observation of many alkali cations is precluded by either low inherent sensitivity or rapid relaxation (or both), the feasibility of proton-detected electrophoretic NMR (ENMR) measurements to complement PGSE data was investigated. ENMR measurements were performed on aqueous Cs+-, Li+-, Na+-, K+-, and Rb+-18-crown-6 systems. The data analysis is based on a two-site binding model and its corresponding association constants. Cs+ was found to bind considerably more tightly to 18-crown-6 (K = 8 m(-1)) than to 15-crown-5 (K similar to 2 m(-1)), whereas Na+ had almost equal affinity (K similar to 4.5 m(-1)) for 15-crown-5 and 18-crown-6. The difficulties encountered in analysing the NMR parameters, methodological limitations and the implied need for more complicated binding models are discussed.
Place, publisher, year, edition, pages
2007. Vol. 45, no 2, 152-156 p.
binding, crown ether, diffusion, electrophoretic NMR, PGSE NMR, NUCLEAR-MAGNETIC-RESONANCE, STUDYING TRANSLATIONAL DIFFUSION, SELF-DIFFUSION, ASSOCIATION CONSTANTS, ALKALINE-EARTH, FIELD GRADIENT, COMPLEX-FORMATION, CRYPTAND 222, METAL IONS, SODIUM-ION
IdentifiersURN: urn:nbn:se:kth:diva-12187DOI: 10.1002/mrc.1936ISI: 000243695200008ScopusID: 2-s2.0-33846648786OAI: oai:DiVA.org:kth-12187DiVA: diva2:305661