{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T01:52:36Z","timestamp":1781747556506,"version":"3.54.5"},"reference-count":60,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2007,10,17]],"date-time":"2007-10-17T00:00:00Z","timestamp":1192579200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Chemistry A European J"],"published-print":{"date-parts":[[2008,1,7]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The irradiation in water of 1\u2010ethyl\u20106,8\u2010difluoro\u20107(3\u2010methylpiperazino)3\u2010quinolone\u20102\u2010carboxylic acid (lomefloxacin), a bactericidal agent whose use is limited by its serious phototoxicity (and photomutagenicity in the mouse), leads to formation of the aryl cation in position eight that inserts into the 1\u2010ethyl chain. Trapping of the cation was examined and it was found that chloride and bromide straightforwardly add in position eight, but with iodide and with pyrrole the 1\u2010(2\u2010iodoethyl) and the 1\u2010[2\u2010(2\u2010pyrrolyl)ethyl] derivatives are formed. Flash photolysis reveals the triplet of lomefloxacin, a short\u2010lived species (<jats:italic>\u03bb<\/jats:italic><jats:sub>max<\/jats:sub>=370\u2005nm, <jats:italic>\u03c4<\/jats:italic>=40\u2005ns) that generates the triplet cation (<jats:italic>\u03bb<\/jats:italic><jats:sub>max<\/jats:sub>=480\u2005nm, <jats:italic>\u03c4<\/jats:italic>\u2248120\u2005ns). The last intermediate is quenched both by halides and by pyrrole. DFT and post\u2010HF methods have shown that the triplet is the lowest state of the cation (\u0394<jats:italic>G<\/jats:italic><jats:sub>ST<\/jats:sub>=13.3\u2005kcal\u2009mol<jats:sup>\u22121<\/jats:sup>) and intersystem crossing (ISC) to the singlet has no role because a less endothermic process occurs, that is, intramolecular hydrogen abstraction from the <jats:italic>N<\/jats:italic>\u2010ethyl chain (9.2\u2005kcal\u2009mol<jats:sup>\u22121<\/jats:sup>) that finally leads to cyclization. The halides form weak complexes with the triplet cation (<jats:italic>k<\/jats:italic><jats:sub>q<\/jats:sub> from 4.9\u00d710<jats:sup>8<\/jats:sup> for Cl<jats:sup>\u2212<\/jats:sup> to 7.0\u00d710<jats:sup>9<\/jats:sup><jats:sc>\u2009m<\/jats:sc><jats:sup>\u22121<\/jats:sup>\u2009s<jats:sup>\u22121<\/jats:sup> for I<jats:sup>\u2212<\/jats:sup>). With Cl<jats:sup>\u2212<\/jats:sup> and Br<jats:sup>\u2212<\/jats:sup> ISC occurs in the complex along with C<jats:sub>8<\/jats:sub>\uf8ffX bond formation. However, this latter process is slow with bulky iodide and with neutral pyrrole, and in these cases moderately endothermic electron transfer (ca. 7\u2005kcal\u2009mol<jats:sup>\u22121<\/jats:sup>) yielding the 8\u2010quinolinyl radical occurs. Hydrogen exchange leads to a new radical on the 1\u2010ethyl chain and to the observed products. These findings suggest that the mutagenic activity of the DNA\u2010intercalated drug involves attack of the photogenerated cation to the heterocyclic bases.<\/jats:p>","DOI":"10.1002\/chem.200701099","type":"journal-article","created":{"date-parts":[[2007,10,17]],"date-time":"2007-10-17T09:50:04Z","timestamp":1192614604000},"page":"653-663","source":"Crossref","is-referenced-by-count":47,"title":["Modeling the Photochemistry of the Reference Phototoxic Drug Lomefloxacin by Steady\u2010State and Time\u2010Resolved Experiments, and DFT and Post\u2010HF Calculations"],"prefix":"10.1002","volume":"14","author":[{"given":"Mauro","family":"Freccero","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elisa","family":"Fasani","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariella","family":"Mella","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ilse","family":"Manet","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sandra","family":"Monti","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Angelo","family":"Albini","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2007,12,19]]},"reference":[{"key":"e_1_2_8_1_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr010046q"},{"key":"e_1_2_8_2_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr9800199"},{"key":"e_1_2_8_3_2","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1098-2280(1998)31:2<105::AID-EM2>3.0.CO;2-L"},{"key":"e_1_2_8_4_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja00084a009"},{"key":"e_1_2_8_5_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja047655a"},{"key":"e_1_2_8_6_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.34.6.1088"},{"key":"e_1_2_8_7_2","unstructured":"\u00a0"},{"key":"e_1_2_8_8_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0887-2333(00)00017-5"},{"key":"e_1_2_8_9_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jphotobiol.2004.11.014"},{"key":"e_1_2_8_10_2","unstructured":"\u00a0"},{"key":"e_1_2_8_11_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1523-1747.2003.12422.x"},{"key":"e_1_2_8_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1383-5718(00)00034-6"},{"key":"e_1_2_8_13_2","unstructured":"\u00a0"},{"key":"e_1_2_8_14_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1011-1344(96)07424-6"},{"key":"e_1_2_8_15_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.0022-202X.2005.23862.x"},{"key":"e_1_2_8_16_2","unstructured":"\u00a0"},{"key":"e_1_2_8_17_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1751-1097.1998.tb05217.x"},{"key":"e_1_2_8_18_2","doi-asserted-by":"publisher","DOI":"10.1007\/BF02035128"},{"key":"e_1_2_8_19_2","doi-asserted-by":"publisher","DOI":"10.1023\/A:1007474912498"},{"key":"e_1_2_8_20_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1751-1097.1997.tb07959.x"},{"key":"e_1_2_8_21_2","doi-asserted-by":"publisher","DOI":"10.1093\/toxsci\/69.1.16"},{"key":"e_1_2_8_22_2","unstructured":"\u00a0"},{"key":"e_1_2_8_23_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1751-1097.1999.tb08308.x"},{"key":"e_1_2_8_24_2","doi-asserted-by":"publisher","DOI":"10.1562\/0031-8655(2001)0730230AOFMPO2.0.CO2"},{"key":"e_1_2_8_25_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja060651g"},{"key":"e_1_2_8_26_2","doi-asserted-by":"publisher","DOI":"10.1002\/1521-3765(20010518)7:10<2185::AID-CHEM2185>3.0.CO;2-U"},{"key":"e_1_2_8_27_2","doi-asserted-by":"publisher","DOI":"10.1021\/jo982456t"},{"key":"e_1_2_8_28_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1011-1344(00)00103-2"},{"key":"e_1_2_8_29_2","doi-asserted-by":"publisher","DOI":"10.1021\/jp060634d"},{"key":"e_1_2_8_30_2","first-page":"451","volume-title":"Divalent Carbocations","author":"Stang P. 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At MP2\/6\u201031G(d) a TS in gas had an activation energy of 3.1\u2005kcal\u2009mol\u22121."},{"key":"e_1_2_8_37_2","doi-asserted-by":"publisher","DOI":"10.1021\/j100398a045"},{"key":"e_1_2_8_38_2","doi-asserted-by":"publisher","DOI":"10.1021\/jp9716997"},{"key":"e_1_2_8_39_2","doi-asserted-by":"publisher","DOI":"10.1021\/jo00185a005"},{"key":"e_1_2_8_40_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja00075a045"},{"key":"e_1_2_8_41_2","unstructured":"\u00a0"},{"key":"e_1_2_8_42_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.46.6.1805-1815.2002"},{"key":"e_1_2_8_43_2","doi-asserted-by":"publisher","DOI":"10.1021\/cr030101q"},{"key":"e_1_2_8_44_2","doi-asserted-by":"publisher","DOI":"10.1021\/bi00435a038"},{"key":"e_1_2_8_45_2","unstructured":"Guanosine is more easily oxidized than pyrrole E=1.29\u2005V vs NHE and thymine less easily; at any rate the process observed will depend on the closest\u2010lying bases in the preferred intercalation;"},{"key":"e_1_2_8_46_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja962255b"},{"key":"e_1_2_8_47_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja058758b"},{"key":"e_1_2_8_48_2","unstructured":"Gaussian 03 Revision C.02 M.\u2005J. 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