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Advances and opportunities in the exciting world of azobenzenes

Nature Reviews Chemistry volume 6, pages 51–69 (2022)Cite this article

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Abstract

Azobenzenes are archetypal molecules that have a central role in fundamental and applied research. Over the course of almost two centuries, the area of azobenzenes has witnessed great achievements; azobenzenes have evolved from simple dyes to ‘little engines’ and have become ubiquitous in many aspects of our lives, ranging from textiles, cosmetics, food and medicine to energy and photonics. Despite their long history, azobenzenes continue to arouse academic interest, while being intensively produced for industrial purposes, owing to their rich chemistry, versatile and straightforward design, robust photoswitching process and biodegradability. The development of azobenzenes has stimulated the production of new coloured and light-responsive materials with various applications, and their use continues to expand towards new high-tech applications. In this Review, we highlight the latest achievements in the synthesis of red-light-responsive azobenzenes and the emerging application areas of photopharmacology, photoswitchable adhesives and biodegradable materials for drug delivery. We show how the synthetic versatility and adaptive properties of azobenzenes continue to inspire new research directions, with limits imposed only by one’s imagination.

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Fig. 1: The evolution of azobenzenes from common dyes to ‘little engines’.
Fig. 2: Photoisomerization mechanism of azobenzene.
Fig. 3: Strategies for the synthesis of red-light-photoresponsive azobenzenes.
Fig. 4: Azologization and azo extension of bioactive molecules.
Fig. 5: Strategies for glueing different surfaces.
Fig. 6: Degradation of azobenzenes under the action of reducing agents.

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Acknowledgements

F.A.J. and V.V.J. acknowledge the Romanian Ministry of Research, Innovation and Digitalization, CNCS/CCCDI–UEFISCDI, project numbers PN-III-P1-1.1-TE-2019-0538 and PN-III-P1-1.1-TE-2019-1696 within PNCDI III, for financial support. R.H. thanks FWO Flanders and Ghent University for continuous financial support.

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  1. These authors contributed equally: Florica Adriana Jerca, Valentin Victor Jerca

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  1. Centre of Organic Chemistry “Costin D. Nenitzescu” Romanian Academy, Bucharest, Romania

    Florica Adriana Jerca & Valentin Victor Jerca

  2. Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Ghent, Belgium

    Richard Hoogenboom

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F.A.J and V.V.J. contributed to the researching of data for the article, discussion of content and writing. R.H. contributed to the discussion of content, writing and editing of the manuscript before submission.

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Jerca, F.A., Jerca, V.V. & Hoogenboom, R. Advances and opportunities in the exciting world of azobenzenes. Nat Rev Chem 6, 51–69 (2022). https://doi.org/10.1038/s41570-021-00334-w

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