Ultrafast Spectroscopy of Hydroxy-Substituted Azobenzenes in Water

Sabrina Steinwand, Thomas Halbritter, Dominique Rastädter, Juan Manuel Ortiz-Sánchez, Irene Burghardt, Alexander Heckel, Josef Wachtveitl*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Ultrafast UV/Vis pump/probe experiments on ortho-, meta- and para-hydroxy-substituted azobenzenes (HO-ABs), as well as for sulfasalazine, an AB-based drug, were performed in aqueous solution. For meta-HO-AB, AB-like isomerisation behaviour can be observed, whereas, for ortho-HO-AB, fast proton transfer occurs, resulting in an excited keto species. For para-HO-AB, considerable keto/enol tautomerism proceeds in the ground state, so after excitation the trans-keto species isomerises into the cis form. Aided by TD-DFT calculations, insight is provided into different deactivation pathways for HO-AB, and reveals the role of hydroxy groups in the photochemistry of ABs, as well as their acetylation regarding sulfasalazine. Hydroxy groups are position-specific substituents for AB, which allow tuning of the timescale of thermal relaxation, as well as the amount and contribution of the keto species to photochemical processes.

Original languageEnglish
Pages (from-to)15720-15731
Number of pages12
JournalChemistry - A European Journal
Issue number44
Publication statusPublished - 1 Oct 2015

Bibliographical note

Publisher Copyright:
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Other keywords

  • azobenzenes
  • photochemistry
  • tautomerism
  • time-resolved spectroscopy
  • water chemistry


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