Novel ion-pair receptors based on hexahomotrioxacalix[3]arene derivatives

Xin-Long Ni, Shofuir Rahman, Xi Zeng, David L. Hughes, Carl Redshaw, Takehiko Yamato

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

series of novel heteroditopic hexahomotrioxacalix[3]arene triamide receptors capable of binding an anion and cation simultaneously in a cooperative fashion have been prepared. The lower rim functionalized cone-hexahomotrioxacalix[3]arene derivatives cone-5a–5d bearing three amide groups were synthesized from cone-3 by a stepwise reaction. The crystal structures of 5c and 5d and 1H NMR studies in nonpolar solvents strongly indicate that a number of interesting intramolecular hydrogen bonding interactions existing in these receptors. The binding abilities of these compounds towards n-butylammonium chloride and bromide salts have been investigated using 1H NMR titration experiments in CDCl3 solvent. Owing to the ‘flattened cone’ conformations and intramolecular hydrogen bonding involving the amide NH and neighbouring O atoms in cone-5a–5d, the affinities toward n-Bu4NX (X= Cl–,and Br–) were weakened. However, it is should be noted that triamides cone-5a–5d show a single selectivity for halides anions in the presence of n-BuNH3+ through the intermolecular hydrogen bonding with the amide NH hydrogen atoms in the receptors in CDCl3 solution. Association constants were calculated from the chemical shift changes of the amide protons.
Original languageEnglish
Pages (from-to)6535-6541
Number of pages7
JournalOrganic & Biomolecular Chemistry
Volume9
Issue number19
DOIs
Publication statusPublished - 2011

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