{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T13:18:23Z","timestamp":1790860703571,"version":"4.1.0"},"reference-count":43,"publisher":"Wiley","issue":"18","license":[{"start":{"date-parts":[[2007,11,30]],"date-time":"2007-11-30T00:00:00Z","timestamp":1196380800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["chemistry-europe.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["ChemPhysChem"],"published-print":{"date-parts":[[2007,12,21]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The photophysical properties of indoline (I) and three of its derivatives, namely, N\u2010methylindoline (MI), 5\u2010cyanoindoline (CI), and 5\u2010cyano\u2010N\u2010methylindoline (CMI), are studied in H\u2010donating solvents of varying polarity. Based on measurements of fluorescence yield and lifetime, and of triplet yield and hydrated\u2010electron formation, two distinct mechanisms of solvent\u2010induced fluorescence quenching are evidenced. The first mechanism involves the cyano substituent and leads to an increase in the rate constant of internal conversion of one order of magnitude in ethanolic solution and of more than two orders of magnitude in water, as compared to solutions in <jats:italic>n<\/jats:italic>\u2010hexane or acetonitrile. A similar trend had previously been observed in the case of 4\u2010N,N\u2010dimethylaminobenzonitrile (DMABN). The second mechanism reduces the fluorescence lifetimes of the non\u2010cyanated derivatives in aqueous solution by one order of magnitude and is related to the formation of hydrated electrons. Neither of these mechanisms is influenced by methylation at the ring nitrogen. Quantum chemical calculations are performed on the ground and excited states of the hydrogen\u2010bonded complexes between protic solvents and MI as well as CMI. Stable hydrogen\u2010bonded configurations involving the CN substituent and a solvent OH group are found; these configurations are stable both in the ground and the first excited singlet states, whereas the corresponding complex at the ring amino nitrogen is stable in the ground state only. The CN\uf8ffHO configuration is therefore a prime candidate for a mechanistic explanation of the observed quenching by the first mechanism. These findings may have useful applications for the design of fluorescence probes for water in biological systems.<\/jats:p>","DOI":"10.1002\/cphc.200700479","type":"journal-article","created":{"date-parts":[[2007,11,30]],"date-time":"2007-11-30T09:19:51Z","timestamp":1196414391000},"page":"2627-2635","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Efficient Singlet\u2010State Deactivation of Cyano\u2010Substituted Indolines in Protic Solvents via CN\uf8ffHO Hydrogen Bonds"],"prefix":"10.1002","volume":"8","author":[{"given":"Krisztina","family":"P\u00e1l","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mih\u00e1ly","family":"K\u00e1llay","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gottfried","family":"K\u00f6hler","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hong","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Istv\u00e1n","family":"Bitter","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mikl\u00f3s","family":"Kubinyi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tam\u00e1s","family":"Vid\u00f3czy","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gottfried","family":"Grabner","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2007,12,13]]},"reference":[{"key":"e_1_2_6_1_2","first-page":"443","volume":"3","author":"Grabowski Z. 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