{
  "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.",
  "abstract_shown": true,
  "affiliations": [
    "Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw, Poland, 01-224",
    "Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, Warsaw, Poland, 00-664"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 7,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Antoni Powała-Borowski"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Magdalena Wiślańska"
    },
    {
      "affs": [
        0
      ],
      "name": "Mateusz Woźny"
    },
    {
      "affs": [
        0
      ],
      "name": "Piotr Krajewski"
    },
    {
      "affs": [
        0
      ],
      "name": "Piotr Cmoch"
    },
    {
      "affs": [
        1
      ],
      "name": "Krzysztof Durka"
    },
    {
      "affs": [
        0
      ],
      "name": "Dorota Gryko",
      "orcid": "0000-0002-5197-4222"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fkdhk9aq2nk9w.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008147/v1",
  "fulltext_url": null,
  "id": "fkdhk9aq2nk9w",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008147/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2505|Photochromic and Fluorescence Chemistry"
    ]
  ],
  "openalex": "W7204957719",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15008147/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-01",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/fkdhk9aq2nk9w.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:17Z",
      "native_id": "10.26434/chemrxiv.15008147",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008147/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:2505|Photochromic and Fluorescence Chemistry",
      "subfield": "materials-polymers"
    }
  ],
  "title": "SYNTHESIS OF AZOPYRIDINES BASED PHOTOSWITCHES VIA ZINCKE IMINE INTERMEDIATES",
  "title_text": "SYNTHESIS OF AZOPYRIDINES BASED PHOTOSWITCHES VIA ZINCKE IMINE INTERMEDIATES",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:17Z",
  "url": "https://research.draconitic.com/paper/fkdhk9aq2nk9w",
  "venue": "ChemRxiv",
  "versions": []
}