Redox-Active Monopyrrolotetrathiafulvalene-Based Rotaxane Incorporating the Dihydroazulene/Vinylheptafulvene Photo/Thermoswitch

Martin Drøhse Kilde, Rikke Kristensen, Gunnar Olsen, Jan O. Jeppesen*, Mogens Brøndsted Nielsen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

A dumbbell-shaped molecule with a central monopyrrolo-tetrathiafulvalene (MPTTF) unit and a 1,1-dicyano-dihydroazulene (DHA) photoswitch as one of the two end-groups was prepared and subsequently converted into a [2]rotaxane with cyclobis(paraquat-p-phenylene) (CBPQT4+) as the ring component. Investigations revealed that both the DHA and its vinylheptafulvene (VHF) photoisomer prevent deslipping of CBPQT4+. It was found that the presence of the CBPQT4+ ring on the MPTTF-DHA dumbbell changes the rate of the thermal back-conversion of VHF into DHA, i.e., this conversion was found to be accelerated by the presence of the positively charged CBPQT4+ ring. Studies also showed that DHA forms a weak complex with CBPQT4+, which seems to originate from weak interactions between the cyano group located on DHA and the bipyridinium α-protons on CBPQT4+. The rotaxane was subjected to various oxidation experiments, but these were, unfortunately, accompanied by some decomposition of the molecule; yet, movement of the CBPQT4+ ring from the MPTTF unit towards the DHA moiety seems to occur upon oxidation of the MPTTF unit, promoted by the weak interaction between the DHA moiety and CBPQT4+.

Original languageEnglish
JournalEuropean Journal of Organic Chemistry
Volume2019
Issue number31-32
Pages (from-to)5532-5539
ISSN1434-193X
DOIs
Publication statusPublished - 1. Sep 2019

Bibliographical note

This article also appears in: Heterocyclic Chemistry

Keywords

  • Heterocycles
  • Host–guest systems
  • Photochromism
  • Redox chemistry
  • Rotaxanes

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