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Substituent effects on ion complexation of para ‐ tert ‐butylcalix[4]arene esters
Author(s) -
Lazzarotto Márcio,
Francisco Marjarie Marrie,
Nachtigall Francine Furtado,
Lazzarotto Marcelo
Publication year - 2006
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1076
Subject(s) - chemistry , substituent , alkali metal , ion , metal , calixarene , hammett equation , metal ions in aqueous solution , phase (matter) , stereochemistry , medicinal chemistry , computational chemistry , inorganic chemistry , organic chemistry , molecule , reaction rate constant , kinetics , physics , quantum mechanics
Phenoxy‐carboxy‐methoxy‐ p‐tert ‐butylcalix[4]arene esters were synthesized in order to evaluate the role of electronic parameters on the complexation of alkaline metal cations. Extraction constants of metal picrates to organic phase were determined. Plots of log ( K R / K H ) against Hammett σ and σ p +gave good linear correlations. The best correlations with σ were obtained for K + and Rb + , while the best correlations with σ p +were obtained for Li + and Na + . All Hammett plots gave a straight descending line, which is consistent with a dependence of the electronic density on the CO. Treatment of data using the Yukawa–Tsuno equation revealed a variation in the contribution of resonance in the complexation of alkaline metal ions, which is maximum for Na + and minimum for Rb + . Electronic parameters were calculated for a related acyclic model structure and only the HOMO energy showed a good correlation with log ( K R / K H ). Copyright © 2007 John Wiley & Sons, Ltd.