XAFS studies of solution-phase complexes of cesium with dibenzo-18-crown-6 ethers

Journal Article · Thu Jul 11 04:00:00 EDT 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp9604608· OSTI ID:374442

Kemner, K M; Elam, W T ^[1]; Hunter, D B; Bertsch, P M ^[2]

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1. Naval Research Lab., Washington, DC (United States)
2. Univ. of Georgia, Aiken, SC (United States)

X-ray absorption fine structure (XAFS) measurements have been made at the Cs LIII absorption edge on (1) 0.04 M acetonitrile solutions with respect to both CsBr and dibenzo-18-crown-6 ether (Cs-D18C6), (2) solids produced by drying the aforementioned Cs-D18C6 solution complex, and (3) crystalline CsBr, CsCl, and CsF powders that were used as standards. XAFS measurements have also been made at the Br K absorption edge on the same 0.04 M solution mentioned above. XAFS analyses of the Cs-D18C6 solution show the presence of a 1:1 Cs-D18C6 complex with a Br contact ion, consistent with previous references derived from {sup 133}Cs nuclear magnetic resonance investigations. For interpretation of the Cs LIII edge data, the choice of a Br counterion reduces the error in determining the presence of a single counterion among the lighter backscattering O and C atoms of the crown ether complex. Observation of the normalized XAFS data for the dried Cs-crown ether solution shows that the Cs atom`s local environments changes from a 1:1 Cs-D18C6 complex to a predominantly crystalline CsBr solid phase. This recrystallization during drying illustrates the importance of in situ methods to characterize chemical speciation in solution. The ability of XAFS to directly probe the ternary Cs-D18C6-Br contact ion pair opens many exciting avenues for improving extraction methodologies. 25 refs., 9 figs., 1 tab.

• DOE Contract Number: AC09-76SR00819
• OSTI ID: 374442
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 28 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ACETONITRILE
CESIUM
CESIUM BROMIDES
CESIUM COMPLEXES
CROWN ETHERS
EXTRACTION
ION PAIRS
MOLECULAR STRUCTURE
SOLUTIONS
X-RAY SPECTRA