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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 15, Number 11
BKCSDE 15(11)
November 20, 1994 

 
Title
Conductometric Behavior of Univalent Cation-Podand Complexes in Methanol
Author
Dae Yeon Kim, Jong Hwa Jung, Jae Sang Chun*, Shim Sung Lee
Keywords
Abstract
The stability constants, log K of the 1 : 1 complexation for IA ions, Ag+, and Tl+ with a series of podands having different aromatic end-groups (Ⅰ-Ⅳ) have been determined conductometrically in methanol at 25.0 ℃. Exceptionally the equivalent conductivity, λeq of Li+ and Na+ were increased by the addition of Ⅰ, because the complexed ions are less mobile than solvated ions. The order of log K values for Ⅰ was Ag+>>Tl+>K+>Na+>Rb+>Cs+>Li+. The log K sequence of the podands for the certain cations was Ⅰ>Ⅱ>Ⅲ≥Ⅳ. And every podands except Ⅳ showed the maximum selectivity for Ag+ among the cations. These results were discussed in terms of the aromatic end-group effects, such as heterodonor atoms or conformational changes by π -π stacking interactions. The detailed conformations of π-π stacking were also discussed by the observations of upfield shifts of some aromatic protons upon complexation from 1H NMR spectra.
Page
967 - 971
Full Text
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