{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T09:02:08Z","timestamp":1785402128937,"version":"3.56.0"},"reference-count":33,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T00:00:00Z","timestamp":1781827200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["NRF-2023R1A2C2004993"],"award-info":[{"award-number":["NRF-2023R1A2C2004993"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]},{"award":["NRF-2023R1A2C2004993"],"award-info":[{"award-number":["NRF-2023R1A2C2004993"]}],"id":[{"id":"https:\/\/ror.org\/013aysd81","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Korean government"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Dioxazolones are important precursors for generating nitrenes (highly reactive intermediates widely used for carbon\u2013nitrogen bond formation in organic synthesis) upon exposure to light or heat. The photochemical reaction dynamics of 3-phenyl-1,4,2-dioxazol-5-one in CHCl3 were investigated using femtosecond time-resolved infrared spectroscopy and electronic structure calculations. Photoexcitation at 267 nm rapidly populates an excited singlet state that serves as the key branching point for subsequent photophysical and photochemical processes. Transient infrared spectra reveal the formation of carbon dioxide, phenyl isocyanate, and singlet benzoyl nitrene through their characteristic vibrational features. Kinetic analysis shows that decarboxylation from the excited singlet state occurs with a time constant of 4.7 \u00b1 1 ns, producing phenyl isocyanate and benzoyl nitrene with time constants of 8.1 \u00b1 2 ns and 11 \u00b1 3 ns, respectively. Competing relaxation pathways include internal conversion to the ground state (7.5 \u00b1 2 ns) and intersystem crossing to the T1 state (25 \u00b1 5 ns). The T1 state relaxes to the ground state (350 \u00b1 30 ns) without contributing to product formation. These results demonstrate that both isocyanate and nitrene products originate from the S1 state and provide detailed mechanistic insight into the competing pathways governing dioxazolone photochemistry in solution.<\/jats:p>","DOI":"10.3390\/ijms27125563","type":"journal-article","created":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T03:09:17Z","timestamp":1782270557000},"page":"5563","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Ultrafast Photochemical Reaction Dynamics of 3-Phenyl-1,4,2-dioxazol-5-one Revealed by Femtosecond Time-Resolved Infrared Spectroscopy"],"prefix":"10.3390","volume":"27","author":[{"given":"Seongbeom","family":"Jeon","sequence":"first","affiliation":[{"name":"Department of Chemistry, Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2418-8020","authenticated-orcid":false,"given":"Juhyang","family":"Shin","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Seongchul","family":"Park","sequence":"additional","affiliation":[{"name":"Institute for Future Earth, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyeonwoong","family":"Bae","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering (BK21 FOUR Graduate Program), Dong-A University, Busan 49315, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0420-5065","authenticated-orcid":false,"given":"Jongwoo","family":"Son","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering (BK21 FOUR Graduate Program), Dong-A University, Busan 49315, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8920-3458","authenticated-orcid":false,"given":"Manho","family":"Lim","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9783","DOI":"10.1021\/acs.joc.3c00399","article-title":"Visible-light-promoted Mn-catalyzed C(sp3)\u2013H amidation with dioxazolones","volume":"88","author":"Du","year":"2023","journal-title":"J. Org. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"13955","DOI":"10.1021\/acscatal.1c04538","article-title":"Visible-light-promoted iron-catalyzed N-arylation of dioxazolones with arylboronic acids","volume":"11","author":"Tang","year":"2021","journal-title":"ACS Catal."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4495","DOI":"10.1002\/adsc.202300693","article-title":"Copper(I)-catalyzed decarboxylative N-phosphorylation: Modular preparation of N-acyl iminophosphoranes using dioxazolones and phosphines","volume":"365","author":"Park","year":"2023","journal-title":"Adv. Synth. Catal."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"4751","DOI":"10.1021\/acscatal.0c00961","article-title":"Dioxazolones: Stable substrates for the catalytic transfer of acyl nitrenes","volume":"10","year":"2020","journal-title":"ACS Catal."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"4212","DOI":"10.1021\/ja9002102","article-title":"Direct observation of acyl azide excited states and their decay processes by ultrafast time resolved infrared spectroscopy","volume":"131","author":"Kubicki","year":"2009","journal-title":"J. Am. Chem. Soc."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"12491","DOI":"10.1021\/acs.chemrev.9b00491","article-title":"Mechanistic development and recent applications of the chan\u2013lam amination","volume":"119","author":"West","year":"2019","journal-title":"Chem. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"7384","DOI":"10.1002\/anie.201201945","article-title":"Nitrene chemistry in organic synthesis: Still in its infancy?","volume":"51","author":"Dequirez","year":"2012","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3251","DOI":"10.1021\/acs.joc.3c02709","article-title":"Organic dye-sensitized nitrene generation: Intermolecular aziridination of unactivated alkenes","volume":"89","author":"Dam","year":"2024","journal-title":"J. Org. Chem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"9751","DOI":"10.1021\/ja109098w","article-title":"Photochemistry of 2-naphthoyl azide. An ultrafast time-resolved UV\u2013Vis and IR spectroscopic and computational study","volume":"133","author":"Kubicki","year":"2011","journal-title":"J. Am. Chem. Soc."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1139","DOI":"10.1070\/RC2007v076n12ABEH003702","article-title":"Study of photochemical transformations of organic azides by matrix isolation techniques and quantum chemistry","volume":"76","author":"Gritsan","year":"2007","journal-title":"Russ. Chem. Rev."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3844","DOI":"10.1021\/cr040055+","article-title":"Kinetics, spectroscopy, and computational chemistry of arylnitrenes","volume":"106","author":"Gritsan","year":"2006","journal-title":"Chem. Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1010","DOI":"10.1039\/b209775c","article-title":"Matrix isolation, time-resolved IR, and computational study of the photochemistry of benzoyl azide","volume":"5","author":"Pritchina","year":"2003","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"4297","DOI":"10.1021\/ja00221a032","article-title":"Aroylnitrenes with singlet ground states: Photochemistry of acetyl-substituted aroyl and aryloxycarbonyl azides","volume":"110","author":"Sigman","year":"1988","journal-title":"J. Am. Chem. Soc."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"5814","DOI":"10.1021\/ja00253a037","article-title":"Are aroylnitrenes ground-state singlets? Photochemistry of.Beta.-naphthoyl azide","volume":"109","author":"Autrey","year":"1987","journal-title":"J. Am. Chem. Soc."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8583","DOI":"10.1021\/jo048433y","article-title":"A comparison of acetyl- and methoxycarbonylnitrenes by computational methods and a laser flash photolysis study of benzoylnitrene","volume":"69","author":"Liu","year":"2004","journal-title":"J. Org. Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2006","DOI":"10.1021\/jo502821y","article-title":"Thermally persistent carbonyl nitrene: FC(O)N","volume":"80","author":"Sun","year":"2015","journal-title":"J. Org. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4925","DOI":"10.1021\/acs.orglett.2c01837","article-title":"Reaction of dioxazolones with boronic acids: Copper-mediated synthesis of N-aryl amides via N-acyl nitrenes","volume":"24","author":"Adegboyega","year":"2022","journal-title":"Org. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e70158","DOI":"10.1002\/adsc.70158","article-title":"Recent advances in photocatalytic transformations of dioxazolones","volume":"367","author":"Gong","year":"2025","journal-title":"Adv. Synth. Catal."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3746","DOI":"10.1021\/ja711346z","article-title":"Study of concerted and sequential photochemical wolff rearrangement by femtosecond UV\u2212Vis and IR spectroscopy","volume":"130","author":"Burdzinski","year":"2008","journal-title":"J. Am. Chem. Soc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"516","DOI":"10.1021\/acs.jpclett.2c03613","article-title":"Dynamics of irreversible NO release from photoexcited molsidomine","volume":"14","author":"Yoon","year":"2023","journal-title":"J. Phys. Chem. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"997","DOI":"10.1103\/PhysRevLett.52.997","article-title":"Density-functional theory for time-dependent systems","volume":"52","author":"Runge","year":"1984","journal-title":"Phys. Rev. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"6615","DOI":"10.1039\/b810189b","article-title":"Long-range corrected hybrid density functionals with damped atom\u2013atom dispersion corrections","volume":"10","author":"Chai","year":"2008","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1007","DOI":"10.1063\/1.456153","article-title":"Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen","volume":"90","author":"Dunning","year":"1989","journal-title":"J. Chem. Phys."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1717","DOI":"10.1016\/0584-8539(74)80122-4","article-title":"Vibrational spectrum, assignment and molecular symmetry of phenyl isocyanate in the liquid phase","volume":"30","author":"Chantry","year":"1974","journal-title":"Spectrochim. Acta A Mol. Spectrosc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1016\/j.saa.2006.06.038","article-title":"The vibrational spectra, assignments and ab initio\/DFT analysis for 3-chloro, 4-chloro and 5-chloro-2-methylphenyl isocyanates","volume":"67","author":"Doddamani","year":"2007","journal-title":"Spectrochim. Acta A Mol. Biomol. Spectrosc."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1007\/s11120-009-9454-y","article-title":"Ultrafast transient absorption spectroscopy: Principles and application to photosynthetic systems","volume":"101","author":"Berera","year":"2009","journal-title":"Photosynth. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"3817","DOI":"10.1039\/D4CP04471A","article-title":"Determination of the rotational isomerization rate along carbon\u2013carbon single bonds in solution","volume":"27","author":"Park","year":"2025","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"8829","DOI":"10.1021\/acs.jpclett.4c02175","article-title":"Dynamics of NO release and linkage isomer formation from S-nitroso-mercaptoethanol in aqueous solutions: Insights from femtosecond infrared spectroscopy","volume":"15","author":"Yoon","year":"2024","journal-title":"J. Phys. Chem. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Yoon, H., Shin, J., Park, S., and Lim, M. (2025). Ultrafast photochemical dynamics of dinitrosyl iron complexes investigated by femtosecond time-resolved infrared spectroscopy. Int. J. Mol. Sci., 26.","DOI":"10.3390\/ijms26188835"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"6796","DOI":"10.1063\/1.462569","article-title":"Electron affinities of the first-row atoms revisited. Systematic basis sets and wave functions","volume":"96","author":"Kendall","year":"1992","journal-title":"J. Chem. Phys."},{"key":"ref_31","unstructured":"Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Petersson, G.A., and Nakatsuji, H. (2016). Gaussian 16 Rev. C.01, Gaussian, Inc."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"114110","DOI":"10.1063\/1.3359469","article-title":"Continuous surface charge polarizable continuum models of solvation. I. General formalism","volume":"132","author":"Scalmani","year":"2010","journal-title":"J. Chem. Phys."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"014108","DOI":"10.1063\/1.1824881","article-title":"Anharmonic vibrational properties by a fully automated second-order perturbative approach","volume":"122","author":"Barone","year":"2004","journal-title":"J. Chem. Phys."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/27\/12\/5563\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T08:01:17Z","timestamp":1782288077000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/27\/12\/5563"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,19]]},"references-count":33,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2026,6]]}},"alternative-id":["ijms27125563"],"URL":"https:\/\/doi.org\/10.3390\/ijms27125563","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,19]]}}}