Fluorinated Phenylazopyrazoles for Monitoring the Photoisomerization in Complex Systems

Year: 2025

Authors: Jakob L., van der Wal J.J., Tovtik R., Copko J., Iagatti A., Donato M.D., Crespi S., Simeth N.A.

Autors Affiliation: Uppsala Univ, Dept Chem, Angstrom Lab, Regementsvagen 10, S-75237 Uppsala, Sweden; Univ Gottingen, Dept Chem, Inst Organ & Biomol Chem, Tammannstr 2, D-37077 Gottingen, Germany; LENS, European Lab Nonlinear Spect, Via Nello Carrara 1, I-50019 Florence, Italy; CNR, INO, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Italy; CNR, ICCOM, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy; Univ Gottingen, Cluster Excellence Multiscale Bioimaging, Mol Machines Networks Excitable Cells MBExC, D-37075 Gottingen, Germany.

Abstract: Photoswitches have been impacting diverse areas of research, introducing means of dynamically regulating their environment through reversible photochemical isomerization. Among the different classes of photoswitches, phenylazopyrazoles (PAPs) stand out due to their facile synthesis, beneficial photochemical properties, and the long thermal stability of their metastable forms. Not surprisingly, they have been applied in different fields, from material sciences to pharmacology. However, once incorporated into complex systems, following the photoisomerization behavior of PAPs with routinely used analytical methods becomes challenging. In this work, we focused on synthesizing and studying the isomerization behavior of a series of differently substituted PAPs possessing two trifluoromethyl groups on the pyrazole moiety (F-PAPs). By studying their isomerization with steady-state and transient absorption spectroscopy, we found marked trends in the isomerization efficiency and photophysical properties of the different switches. Most importantly, these molecules can quantitatively isomerize between their stable and metastable forms, with relatively long lifetimes of thermal back relaxation. Leveraging these characteristics, we highlight in this work the potential application of F-PAPs as photoswitchable 19F-NMR probes to generate light-responsive vesicles.

Journal/Review: CHEMISTRY-A EUROPEAN JOURNAL

Volume: 31 (43)      Pages from:   to:

More Information: The authors thank Prof. Dr. Andreas Orthaber (Uppsala University) for his help with the X-Ray analysis and Martina Pretor (Alcarazo Group, University of Goettingen) for the timely donation of hexafluoro acetylacetone. We thank the Swedish Vetenskapsradet for Starting Grant (2021-05414 to S.C. and 2023-04088 to N.A.S.). This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the framework of RTG BENCh (389479699/GRK2455 to R.T. and N.A.S.) and under Germany’s Excellence Strategy (EXC 2067/1-390729940 to N.A.S.). S.C. thanks the Stiftelsen Lars Hiertas Minne (FO2022-0139), and the Goran Gustafsson Foundation. The research leading to these results has received funding from LASERS4EU (grant agreement no. 101131771, European Union’s Horizon Europe programme, visit ID 68056). M.D.D. and A.I. acknowledge support from the European Union’s Next Generation EU Program with the I-PHOQS Infrastructure [Nos. IR0000016, ID D2B8D520, and CUP B53C22001750006] Integrated infrastructure initiative in Photonic and Quantum Sciences.
KeyWords: bioorganic chemistry; photochemistry; photochromism; photoswitches; time-resolved spectroscopy
DOI: 10.1002/chem.202501856