{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T13:07:06Z","timestamp":1788959226196,"version":"build-2803163510"},"reference-count":37,"publisher":"Wiley","license":[{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["chemistry-europe.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Chemistry A European J"],"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    We report the synthesis of novel aryl\u2010azo pyrazino\u2010triazapentalenes through electrophilic coupling of\n                    <jats:italic>in situ<\/jats:italic>\n                    generated diazonium salts derived from\n                    <jats:italic>ortho, ortho\u2032\u2010<\/jats:italic>\n                    dichloro\/difluoro anilines with a mesoionic pyrazino\u2010triazapentalene (PyTAP) scaffold. The coupling reaction afforded two regioisomers, distinguished by their color, assigned as C9 (pink) and C7 (red) substituted products, based on single\u2010crystal x\u2010ray diffraction and NMR analysis. The photoswitching behavior of the resulting azo derivatives was investigated using UV\u2013vis and\n                    <jats:sup>1<\/jats:sup>\n                    H NMR spectroscopy. Three of the six compounds exhibited reversible\n                    <jats:italic>E\u2194Z<\/jats:italic>\n                    isomerization. The C9\u2010substituted derivatives responded more efficiently to light irradiation than their C7 analogues, which were thermally and photochemically labile. The thermal half\u2010lives ranged from minutes to hours and correlated with the calculated Wiberg bond indices of the central N\u2550N bond. Contrary to trends reported in the literature, the chlorinated compounds exhibited better switching performance than the fluorinated derivatives. DFT and TD\u2010DFT calculations provided a rationale for the observed regioselectivity of the diazo\u2010coupling reaction, substituent\u2010dependent absorption profiles, and photoswitching behavior.\n                  <\/jats:p>","DOI":"10.1002\/chem.71668","type":"journal-article","created":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T12:20:20Z","timestamp":1788956420000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Synthesis of azo\u2010Triazapentalenes and Study of their Photoswitching"],"prefix":"10.1002","author":[{"given":"Maria","family":"Popescu","sequence":"first","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0433-752X","authenticated-orcid":false,"given":"Anamaria","family":"Hanganu","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"},{"name":"C. D. Nenitzescu\" Institute of Organic and Supramolecular Chemistry of the Romanian Academy  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7917-7348","authenticated-orcid":false,"given":"Bogdan C.","family":"Enache","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"},{"name":"SC Microsin SRL  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cristina","family":"Tablet","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"},{"name":"Faculty of Pharmacy Titu Maiorescu University  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Augustin M.","family":"Madalan","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anca","family":"Paun","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Codruta C.","family":"Popescu","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Otmane","family":"Bourzikat","sequence":"additional","affiliation":[{"name":"CNRS ICOA UMR 7311 Universit\u00e9 d'Orl\u00e9ans Orl\u00e9ans France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9476-9176","authenticated-orcid":false,"given":"Marie\u2010Aude","family":"Hiebel","sequence":"additional","affiliation":[{"name":"CNRS ICOA UMR 7311 Universit\u00e9 d'Orl\u00e9ans Orl\u00e9ans France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1394-1603","authenticated-orcid":false,"given":"Franck","family":"Suzenet","sequence":"additional","affiliation":[{"name":"CNRS ICOA UMR 7311 Universit\u00e9 d'Orl\u00e9ans Orl\u00e9ans France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7956-7162","authenticated-orcid":false,"given":"Mihaela","family":"Matache","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Organic Chemistry Biochemistry and Catalysis Research Centre of Applied Organic Chemistry Faculty of Chemistry University of Bucharest  Bucharest Romania"},{"name":"Interdisciplinary School of Doctoral Studies (ISDS\u2010UB) Faculty of Interdisciplinary Studies University of Bucharest  Bucharest Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,9,9]]},"reference":[{"key":"e_1_2_9_2_1","volume-title":"Photochromism: Molecules and Systems","author":"D\u00fcrr H.","year":"2003"},{"key":"e_1_2_9_3_1","doi-asserted-by":"crossref","first-page":"1911","DOI":"10.1039\/C7CS00772H","article-title":"The (photo)Chemistry of Stenhouse Photoswitches: Guiding Principles and System Design","volume":"47","author":"Lerch M. M.","year":"2018","journal-title":"Chemical Society Reviews"},{"key":"e_1_2_9_4_1","doi-asserted-by":"crossref","first-page":"1809","DOI":"10.1039\/C1CS15179G","article-title":"Photoisomerization in Different Classes of Azobenzene","volume":"41","author":"Bandara H. M. D.","year":"2012","journal-title":"Chemical Society Reviews"},{"key":"e_1_2_9_5_1","doi-asserted-by":"crossref","first-page":"14982","DOI":"10.1021\/jacs.5b09519","article-title":"Acylhydrazones as Widely Tunable Photoswitches","volume":"137","author":"Dijken D. J.","year":"2015","journal-title":"Journal of the American Chemical Society"},{"key":"e_1_2_9_6_1","doi-asserted-by":"crossref","first-page":"21663","DOI":"10.1002\/anie.202008700","article-title":"General Principles for the Design of Visible\u2010light\u2010Lesponsive Photoswitches: Tetra\u2010 ortho \u2010chloro\u2010azobenzenes","volume":"59","author":"Lameijer L. N.","year":"2020","journal-title":"Angewandte Chemie International Edition"},{"key":"e_1_2_9_7_1","doi-asserted-by":"crossref","first-page":"9777","DOI":"10.1021\/ja402220t","article-title":"Photoswitching Azo Compounds in Vivo With Red Light","volume":"135","author":"Samanta S.","year":"2013","journal-title":"Journal of the American Chemical Society"},{"key":"e_1_2_9_8_1","doi-asserted-by":"crossref","first-page":"20597","DOI":"10.1021\/ja310323y","article-title":"o \u2010Fluoroazobenzenes as Readily Synthesized Photoswitches Offering Nearly Quantitative Two\u2010way Isomerization With Visible Light","volume":"134","author":"Bl\u00e9ger D.","year":"2012","journal-title":"Journal of the American Chemical Society"},{"key":"e_1_2_9_9_1","doi-asserted-by":"crossref","first-page":"16492","DOI":"10.1002\/chem.201404649","article-title":"Ortho\u2010Fluoroazobenzenes: Visible Light Switches With Very Long\u2010Lived Z Isomers","volume":"20","author":"Knie C.","year":"2014","journal-title":"Chemistry\u2014A European Journal"},{"key":"e_1_2_9_10_1","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1038\/s41570-019-0074-6","article-title":"Heteroaryl Azo Dyes as Molecular Photoswitches","volume":"3","author":"Crespi S.","year":"2019","journal-title":"Nature Reviews Chemistry"},{"key":"e_1_2_9_11_1","doi-asserted-by":"crossref","first-page":"11878","DOI":"10.1021\/ja505444d","article-title":"Arylazopyrazoles: Azoheteroarene Photoswitches Offering Quantitative Isomerization and Long Thermal Half\u2010Lives","volume":"136","author":"Weston C. E.","year":"2014","journal-title":"Journal of the American Chemical Society"},{"key":"e_1_2_9_12_1","doi-asserted-by":"crossref","first-page":"1261","DOI":"10.1021\/jacs.6b11626","article-title":"Tuning Azoheteroarene Photoswitch Performance Through Heteroaryl Design","volume":"139","author":"Calbo J.","year":"2017","journal-title":"Journal of the American Chemical Society"},{"key":"e_1_2_9_13_1","doi-asserted-by":"crossref","first-page":"4307","DOI":"10.1021\/acs.joc.7b02604","article-title":"Evaluation of Substituent Effect in Z\u2010Isomer Stability of Arylazo\u20101H\u20103,5\u2010Dimethylpyrazoles: Interplay of Steric, Electronic Effects and Hydrogen Bonding","volume":"83","author":"Devi S.","year":"2018","journal-title":"Journal of Organic Chemistry"},{"key":"e_1_2_9_14_1","doi-asserted-by":"crossref","first-page":"4079","DOI":"10.1021\/acs.joc.9b03097","article-title":"Photochromic Evaluation of 3(5) \u2010arylazo\u20101 H \u2010pyrazoles","volume":"85","author":"Rustler K.","year":"2020","journal-title":"Journal of Organic Chemistry"},{"key":"e_1_2_9_15_1","doi-asserted-by":"crossref","first-page":"39122","DOI":"10.1021\/acsomega.2c04984","article-title":"Exploring Arylazo\u20103,5\u2010bis(trifluoromethyl)Pyrazole Switches","volume":"7","author":"Enache B. 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A.","year":"2011","journal-title":"Journal of the American Chemical Society"},{"key":"e_1_2_9_18_1","doi-asserted-by":"crossref","first-page":"5091","DOI":"10.1021\/acs.orglett.7b02361","article-title":"Two\u2010step, One\u2010pot Synthesis of Visible\u2010Light\u2010Responsive 6\u2010Azopurines","volume":"19","author":"Kolarski D.","year":"2017","journal-title":"Organic Letters"},{"key":"e_1_2_9_19_1","doi-asserted-by":"crossref","first-page":"14292","DOI":"10.1002\/chem.201502858","article-title":"Spatially Close Azo Dyes With Sub\u2010Nanosecond Switching Speeds and Exceptional Temporal Resolution","volume":"21","author":"Garc\u00eda\u2010Amor\u00f3s J.","year":"2015","journal-title":"Chemistry \u2013 A European Journal"},{"key":"e_1_2_9_20_1","doi-asserted-by":"crossref","first-page":"3421","DOI":"10.1039\/c2cc17782j","article-title":"Light\u2010controlled Real Time Information Transmitting Systems Based on Nanosecond Thermally\u2010Isomerising Amino\u2010azopyridinium Salts","volume":"48","author":"Garcia\u2010Amor\u00f3s J.","year":"2012","journal-title":"Chemical Communications"},{"key":"e_1_2_9_21_1","doi-asserted-by":"crossref","first-page":"4875","DOI":"10.1021\/acs.orglett.8b02014","article-title":"Synthesis and Photophysical Characterization of Azoheteroarenes","volume":"20","author":"Xu Y.","year":"2018","journal-title":"Organic Letters"},{"key":"e_1_2_9_22_1","doi-asserted-by":"crossref","first-page":"3587","DOI":"10.1055\/a-2675-3787","article-title":"Light\u2010responsive Oxadiazole\u2010Based (hetero)Aryl\u2010Azobenzenes","volume":"57","author":"Enache B. 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