Abstract
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 language | English |
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Pages (from-to) | 2398-2407 |
Number of pages | 10 |
Journal | Beilstein Journal of Organic Chemistry |
Volume | 15 |
DOIs | |
Publication status | Published - Oct 10 2019 |
Keywords
- Arylazopyrazoles
- Coordination cages
- Inclusion complexes
- Molecular switches
- Photochromism
ASJC Scopus subject areas
- Organic Chemistry