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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 26, Number 3
BKCSDE 26(3)
March 20, 2005 

Diaza-18-crown-6 Ethers Containing Partially-fluorinated Benzyl Sidearms: Effects of Covalently Bonded Fluorine on the Alkali Metal Complexation
Ki-Whan Chi*, Kwang Taeg Shim, Hwang Huh, Uk Lee, Young Ja Park
Diaza-18-crown-6 ethers, Partially-fluorinated benzyl sidearms, Alkali metal cation complexation, Stability constant
The stability constants for the diaza-18-crown-6 ethers 2-6 and alkali metal cations (Na+, K+, Rb+ and Cs+) were determined using potentiometry in 95% methanol. For each metal ion the stability constants of the partiallyfluorinated ligands 3-6 were larger than that of the non-fluorinated ligand 2, which might reflect an interaction between fluorine atoms and alkali metal cations. The stability constant of the ligand 4 was larger than that of the ligand 5 for each metal cation tested. This finding was also supported by the results of cation-induced chemical shifts in 1H-, 19F-NMR and extraction experiment. The potentiometry and NMR results as well as the X-ray crystal structures revealed that the position and number of fluorine atoms in the benzyl side arms was crucial for the enhanced interaction between a ligand and an alkali metal.
393 - 398
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