SYNTHESIS OF AZOPYRIDINES BASED PHOTOSWITCHES VIA ZINCKE IMINE INTERMEDIATES
- 1Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, Poland, 01-224
- 2Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, Warsaw, Poland, 00-664
Abstract
Azopyridines are an underexplored subclass of heteroaryl azo photoswitches whose pyridine nitrogen confers pH- and metal-responsiveness in addition to reversible E/Z-photoisomerization, yet no general method exists for their regioselective synthesis. Here we report that aryl diazonium salts undergo direct electrophilic azo coupling to Zincke imine intermediates, providing a mild, two-step route to substituted azopyridines that operate exclusively on the dearomatized pyridine core, leaving electron-rich aryl substituents untouched. Reaction conditions were optimized using a Design of Experiments/Response Surface Methodology approach. The method tolerates a broad range of diazonium and Zincke imine substituents including halogens, methoxy, nitro, cyano, extended aromatic and heteroaromatic systems, furnishing the first complete set of positional isomers bearing a substituent at C2, C3, C4, and C5 of the 3-azopyridine ring, and enabling 15N labelling in the parent pyridine ring. UV-Vis and DFT/TD-DFT studies reveal red-shifted, structurally tuneable π→π* absorption relative to azobenzene, while photoisomerization experiments show fatigue-resistant bidirectional switching up to >80% conversion in both directions with thermal Z-isomer half-lives spanning hours to weeks. This work establishes Zincke imine chemistry as a general platform for azopyridine synthesis and provides a structurally diverse toolkit for structure–property evaluation.
Related
- Optimizing the synthesis of imine-linked covalent organic frameworks for high surface areas
- Enantio-Complementary Synthesis of Atropisomeric C–N Biaryl Amines via Imine Reductase-Mediated Dynamic Kinetic Resolution
- Sonochemical synthesis of imine- and aminal-linked porous organic polymers for efficient CO2 separation
- Efficient and Practical Synthesis of β-Naphthol-Substituted 2-Azetines via Vinylidene ortho-Quinone Methide (VQM) Intermediates
- High Fatigue‐Resistant Photoswitches Based on iridium(III)‐DTE Systems
BibTeX
@misc{powalaborowski2026synthesis,
title = {{SYNTHESIS OF AZOPYRIDINES BASED PHOTOSWITCHES VIA ZINCKE IMINE INTERMEDIATES}},
author = {Antoni Powała-Borowski and Magdalena Wiślańska and Mateusz Woźny and Piotr Krajewski and Piotr Cmoch and Krzysztof Durka and Dorota Gryko},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008147/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008147/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - SYNTHESIS OF AZOPYRIDINES BASED PHOTOSWITCHES VIA ZINCKE IMINE INTERMEDIATES
AU - Antoni Powała-Borowski
AU - Magdalena Wiślańska
AU - Mateusz Woźny
AU - Piotr Krajewski
AU - Piotr Cmoch
AU - Krzysztof Durka
AU - Dorota Gryko
PY - 2026
DA - 2026/09/01
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008147/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008147/v1
AB - Azopyridines are an underexplored subclass of heteroaryl azo photoswitches whose pyridine nitrogen confers pH- and metal-responsiveness in addition to reversible E/Z-photoisomerization, yet no general method exists for their regioselective synthesis. Here we report that aryl diazonium salts undergo direct electrophilic azo coupling to Zincke imine intermediates, providing a mild, two-step route to substituted azopyridines that operate exclusively on the dearomatized pyridine core, leaving electron-rich aryl substituents untouched. Reaction conditions were optimized using a Design of Experiments/Response Surface Methodology approach. The method tolerates a broad range of diazonium and Zincke imine substituents including halogens, methoxy, nitro, cyano, extended aromatic and heteroaromatic systems, furnishing the first complete set of positional isomers bearing a substituent at C2, C3, C4, and C5 of the 3-azopyridine ring, and enabling 15N labelling in the parent pyridine ring. UV-Vis and DFT/TD-DFT studies reveal red-shifted, structurally tuneable π→π* absorption relative to azobenzene, while photoisomerization experiments show fatigue-resistant bidirectional switching up to >80% conversion in both directions with thermal Z-isomer half-lives spanning hours to weeks. This work establishes Zincke imine chemistry as a general platform for azopyridine synthesis and provides a structurally diverse toolkit for structure–property evaluation.
ER -