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In particular, SHI radicals exhibiting significant spatial overlap between the SOMO and HOMO are especially fascinating. However, their development has been hindered by their low stability and the lack of a concrete molecular design principle. Herein, we report the synthesis and isolation of a thermodynamically stabilized \u03c0-conjugated nitroxide radical with SHI electronic configuration. The SHI radical, designed by introducing electron-donating diphenylamino groups at carbon atoms with large HOMO coefficients but negligible SOMO coefficients, exhibited unique properties such as the generation of a triplet-ground-state diradical cation upon electrochemical oxidation and spin-center transfer induced by protonation and hydrogen-bonding interactions. By utilizing these properties, multiple NIR chromisms, including electrochromism, halochromism, and thermochromism, were achieved. These findings establish a molecular design principle for stable SHI radicals with significant SOMO\u2013HOMO overlap and provide a platform for developing functional organic radical-based materials responsive to multiple external stimuli.<\/jats:p>","DOI":"10.1021\/jacs.6c10503","type":"journal-article","created":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T19:29:56Z","timestamp":1788290996000},"page":"38173-38183","source":"Crossref","is-referenced-by-count":0,"title":["Thermodynamically Stabilized\n\u03c0-Conjugated\nNitroxide with SOMO\u2013HOMO Energy Level Inversion"],"prefix":"10.1021","volume":"148","author":[{"given":"Yuka","family":"Kuno","sequence":"first","affiliation":[{"name":"The University of Osaka , , , ,","place":["Toyonaka, Osaka, Japan, 560-8531"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Misaki","family":"Kuroda","sequence":"additional","affiliation":[{"name":"The University of Osaka , , , ,","place":["Toyonaka, Osaka, Japan, 560-8531"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9392-2087","authenticated-orcid":true,"given":"Akihiro","family":"Shimizu","sequence":"additional","affiliation":[{"name":"The University of Osaka , , , ,","place":["Toyonaka, Osaka, Japan, 560-8531"]},{"name":"The University of Osaka , , , ,","place":["Suita, Osaka, Japan, 565-0871"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2013-4394","authenticated-orcid":true,"given":"Manabu","family":"Abe","sequence":"additional","affiliation":[{"name":"Hiroshima University , , ,","place":["Hiroshima, Japan, 739-8526"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6005-7629","authenticated-orcid":true,"given":"Ryohei","family":"Kishi","sequence":"additional","affiliation":[{"name":"The University of Osaka , , , ,","place":["Suita, Osaka, Japan, 565-0871"]},{"name":"The University of Osaka , , , ,","place":["Toyonaka, Osaka, Japan, 560-8531"]},{"name":"The University of Osaka , , , ,","place":["Toyonaka, Osaka, Japan, 560-8531"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3324-9393","authenticated-orcid":true,"given":"Ryo","family":"Shintani","sequence":"additional","affiliation":[{"name":"The University of Osaka , , , ,","place":["Toyonaka, Osaka, Japan, 560-8531"]},{"name":"The University of Osaka , , , ,","place":["Suita, Osaka, Japan, 565-0871"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,8,27]]},"reference":[{"key":"2026090910082286400_cit1","doi-asserted-by":"crossref","DOI":"10.1002\/9780470666975","volume-title":"Stable Radicals:\nFundamentals and Applied Aspects of Odd-Electron Compounds","author":"Hicks","year":"2010"},{"key":"2026090910082286400_cit2","doi-asserted-by":"publisher","first-page":"7011","DOI":"10.1021\/cr400056a","article-title":"Diradicals","volume":"113","author":"Abe","year":"2013","journal-title":"Chem. 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Soc."},{"key":"2026090910082286400_cit22","doi-asserted-by":"publisher","first-page":"4955","DOI":"10.1021\/acs.orglett.1c01137","article-title":"SOMO\u2013HOMO Conversion\nin Triplet Carbenes","volume":"23","author":"Murata","year":"2021","journal-title":"Org. Lett."},{"key":"2026090910082286400_cit23","doi-asserted-by":"publisher","first-page":"22773","DOI":"10.1021\/acsomega.1c03125","article-title":"SOMO\u2013HOMO\nConversion in Triplet\nCyclopentane-1,3-diyl Diradicals","volume":"6","author":"Wang","year":"2021","journal-title":"ACS Omega"},{"key":"2026090910082286400_cit24","doi-asserted-by":"publisher","first-page":"7298","DOI":"10.1021\/jacs.6b01498","article-title":"Radical Cation and\nNeutral Radical\nof Aza-thia[7]helicene with SOMO\u2013HOMO Energy Level Inversion","volume":"138","author":"Wang","year":"2016","journal-title":"J. Am. Chem. Soc."},{"key":"2026090910082286400_cit25","doi-asserted-by":"publisher","first-page":"17287","DOI":"10.1021\/jacs.9b08711","article-title":"High-Spin\nDiradical Dication of Chiral \u03c0-Conjugated Double Helical Molecule","volume":"141","author":"Shu","year":"2019","journal-title":"J. Am. Chem. Soc."},{"key":"2026090910082286400_cit26","doi-asserted-by":"publisher","first-page":"9422","DOI":"10.1021\/jacs.4c02057","article-title":"Chiral \u03c0-Conjugated Double\nHelical Aminyl Diradical with the Triplet Ground State","volume":"146","author":"Guo","year":"2024","journal-title":"J. Am. Chem. Soc."},{"key":"2026090910082286400_cit27","doi-asserted-by":"publisher","DOI":"10.1093\/bulcsj\/uoaf072","article-title":"Synthesis, characterization,\nand magnetic interactions of carbazole-9-oxyl and its derivatives","volume":"98","author":"Kuno","year":"2025","journal-title":"Bull. Chem. Soc. Jpn."},{"key":"2026090910082286400_cit28","doi-asserted-by":"publisher","first-page":"3384","DOI":"10.1002\/adsc.202200819","article-title":"Synthesis of Diarylaminoacridinium\nPhotocatalysts by Halogen-Metal Exchange Combined with Directed ortho\nMetalations","volume":"364","author":"Jakobi","year":"2022","journal-title":"Adv. Synth. Catal."},{"key":"2026090910082286400_cit29","doi-asserted-by":"publisher","first-page":"15154","DOI":"10.1021\/acs.joc.0c02020","article-title":"Catalytic\nand Aerobic Oxidative Biaryl Coupling of Anilines Using a Recyclable\nHeterogeneous Catalyst for Synthesis of Benzidines and Bicarbazoles","volume":"85","author":"Matsumoto","year":"2020","journal-title":"J. Org. Chem."},{"key":"2026090910082286400_cit30","doi-asserted-by":"publisher","first-page":"764","DOI":"10.1063\/1.1742605","article-title":"Indirect\nHyperfine Interactions in the Paramagnetic Resonance Spectra of Aromatic\nFree Radicals","volume":"24","author":"McConnell","year":"1956","journal-title":"J. Chem. Phys."},{"key":"2026090910082286400_cit31","doi-asserted-by":"publisher","first-page":"3717","DOI":"10.1063\/1.1725081","article-title":"Hyperfine Interactions and Electron\nSpin Distribution in Triplet\u2013State Naphthalene","volume":"40","author":"Hirota","year":"1964","journal-title":"J. Chem. 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Chem., Int. Ed."},{"key":"2026090910082286400_cit44","doi-asserted-by":"publisher","first-page":"7277","DOI":"10.1002\/anie.200502180","article-title":"Spin Transfer\nand Solvato-\/Thermochromism\nInduced by Intramolecular Electron Transfer in a Purely Organic Open-Shell\nSystem","volume":"44","author":"Nishida","year":"2005","journal-title":"Angew. Chem., Int. Ed."},{"key":"2026090910082286400_cit45","doi-asserted-by":"publisher","first-page":"500","DOI":"10.1002\/asia.201301188","article-title":"Hydrogen-Bonding\nEffect on Spin-Center\nTransfer of Tetrathiafulvalene-Linked 6-Oxophenalenoxyl Evaluated\nUsing Temperature-Dependent Cyclic Voltammetry and Theoretical Calculations","volume":"9","author":"Nishida","year":"2014","journal-title":"Chem.\u2500Asian J."},{"key":"2026090910082286400_cit46","doi-asserted-by":"publisher","first-page":"1735","DOI":"10.1039\/p29950001735","article-title":"1,1,1,3,3,3-Hexafluoropropan-2-ol\nas a solvent for the generation of highly persistent radical cations","author":"Eberson","year":"1995","journal-title":"J. Chem. Soc., Perkin Trans. 2"}],"container-title":["Journal of the American\nChemical Society"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/jacs.6c10503","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/jacsat\/article-pdf\/148\/35\/38173\/67506835\/jacs.6c10503.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/jacsat\/article-pdf\/148\/35\/38173\/67506835\/jacs.6c10503.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T15:28:14Z","timestamp":1788967694000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/jacsat\/article\/148\/35\/38173\/5338818\/Thermodynamically-Stabilized-Conjugated-Nitroxide"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,27]]},"references-count":45,"journal-issue":{"issue":"35","published-online":{"date-parts":[[2026,8,27]]},"published-print":{"date-parts":[[2026,9,9]]}},"URL":"https:\/\/doi.org\/10.1021\/jacs.6c10503","relation":{},"ISSN":["0002-7863","1520-5126"],"issn-type":[{"value":"0002-7863","type":"print"},{"value":"1520-5126","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,27]]}}}