Substituent effects in the binding of bis(4-fluorobenzyl)ammonium ions by dianilino[24]crown-8
Resource
Tetrahedron Letters 45 (1): 213-216
Journal
Tetrahedron Letters
Journal Volume
45
Journal Issue
1
Pages
213-216
Date Issued
2004
Author(s)
Abstract
A series of para-substituted dianilino[24]crown-8 (DA24C8) macrocycles were synthesized and their ability to form host-guest complexes with bis(4-fluorobenzyl)ammonium ions (DFA+) were investigated. Although these crown ethers contain weakly hydrogen bonding aniline motifs, they do bind DFA+ in CDCl3/CD3NO2 solution, presumably in a pseudorotaxane-like manner. A plot of the values of the relative binding strengths (log[Ka(R)/Ka(H)]) versus the Hammett substituent constants σ+ of the groups at the para-position of the aniline units suggests that a linear free energy correlation exists for this self-assembly process. The strength of the binding between the crown ether and the thread-like ion can be fine-tuned over a narrow range by judicious choice of the substituting groups. © 2003 Elsevier Ltd. All rights reserved.
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journal article
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