Interplay of p-sulfonatocalix[4]arene and crown ethers en route to molecular capsules and "Russian dolls"

Scott J Dalgarno, Julie Fisher, Colin L Raston

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Diffusion-ordered H-1 NMR spectroscopy techniques have been used to determine the binding strength of p-sulfonatocalix[4]arene (SO3[4]) towards a number of charged crown ether species in aqueous conditions. For several (doubly) charged (di)azacrown ethers, all were bound by SO3[4] either well or very well with binding constants between 5.1 x 10(2) - 9.9 x 10(5) m(-1). These results correlate with, and thus explain the phenomenon of rapid capture of azacrown ethers in molecular capsules based on p-sulfonatocalix[4]arene and lanthanide metals. Similarly, the formation of ``Russian doll'' superanions in the solution phase is also elucidated. These superanions have been shown to selectively crystallise particular polynuclear aquated metal ions from mixtures in the aqueous phase. Neutral [18]crown-6 is not bound by p-sulfonatocalix[4]arene and displays a binding constant of 0 m(-1). When sodium [18]crown-6 is examined in a similar fashion, binding by SO3[4] is observed in solution with K-a similar to 3.1 x 10(3) m(-1).
Original languageEnglish
Pages (from-to)2772-2777
Number of pages6
JournalChemistry - A European Journal
Volume12
Issue number10
DOIs
Publication statusPublished - 20 Mar 2006

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