Proton ionizable 1H-1,2,4-triazole π-electron deficient cyclophanes as hosts and in [2]catenanes

Susana Ramos, Ermitas Alcalde, J Fraser Stoddart, Andrew J.P. White, David J. Williams, Lluïsa Pérez-García

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

The incorporation of proton ionizable moieties, such as 1H-1,2,4-triazole rings, within cyclophanes and π-donor/π-acceptor [2]catenanes is explored as a tool of inducing chemical switchability through either the inherent prototropic tautomerism or chemical deprotonation. Bearing this in mind, in this paper we describe the template-directed synthesis of two tetracationic cyclophanes incorporating two bipyridinium units linked by either one 3,5-bis(methylene)-1H-1,2,4-triazole unit and a p-xylyl unit or two 3,5-bis(methylene)-1H-1,2,4-triazole units, as well as the template-directed synthesis of two [2]catenanes wherein these π-acceptor cyclophanes are interlocked with (bis-p-phenylene-34-crown-10), as the π-electron rich polyether macrocycle. We also report on the full characterization of the cyclophanes and the [2]catenanes by electrospray mass spectrometry (ESMS) and fast atom bombardment mass spectrometry (FABMS), X-ray crystallography of the [2]catenanes and dynamic 1 H NMR spectroscopy. We reveal that the [2]catenane incorporating one triazole ring in the tetracationic cyclophane exists, in the solid-state, as hydrogen bond cross-linked enantiomeric pair stacks, whereas the [2]catenane incorporating two triazole rings in the tetracationic cyclophane does not form polar stacks, unlike most of the [2]catenanes of this class. Finally, we studied the chemical stability of these π-donor/π-acceptor motifs to explore their chemical switchability, to show the triazolate-bipyridinium pair is a challenging one in this sense.

Original languageEnglish (US)
Pages (from-to)300-317
Number of pages18
JournalNew Journal of Chemistry
Volume33
Issue number2
DOIs
StatePublished - Feb 11 2009

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Materials Chemistry

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