Reversible switching of arylazopyrazole within a metal-organic cage

Anton I. Hanopolskyi, Soumen De, Michał J. Białek, Yael Diskin-Posner, Liat Avram, Moran Feller, Rafal Klajn

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Arylazopyrazoles represent a new family of molecular photoswitches characterized by a near-quantitative conversion between two states and long thermal half-lives of the metastable state. Here, we investigated the behavior of a model arylazopyrazole in the presence of a self-assembled cage based on Pd-imidazole coordination. Owing to its high water solubility, the cage can solubilize the E isomer of arylazopyrazole, which, by itself, is not soluble in water. NMR spectroscopy and X-ray crystallography have independently demonstrated that each cage can encapsulate two molecules of E-arylazopyrazole. UV-induced switching to the Z isomer was accompanied by the release of one of the two guests from the cage and the formation of a 1:1 cage/Z-arylazopyrazole inclusion complex. DFT calculations suggest that this process involves a dramatic change in the conformation of the cage. Back-isomerization was induced with green light and resulted in the initial 1:2 cage/E-arylazopyrazole complex. This back-isomerization reaction also proceeded in the dark, with a rate significantly higher than in the absence of the cage.

Original languageEnglish
Pages (from-to)2398-2407
Number of pages10
JournalBeilstein Journal of Organic Chemistry
Publication statusPublished - Oct 10 2019


  • Arylazopyrazoles
  • Coordination cages
  • Inclusion complexes
  • Molecular switches
  • Photochromism

ASJC Scopus subject areas

  • Organic Chemistry

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