Fluorescence lifetimes of jet-cooled carbonyl-substituted indoles. Evidence of intramolecular charge transfer quenching

✍ Scribed by Steven Arnold; Mark Sulkes

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 412 KB
• Volume: 200
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(92)87056-u

✦ Synopsis

Fluorescence lifetime measurements were made for the S, origins of a number of jet-cooled indole chromophores having carbonyl-containing substituents bonded directly to the chromophore with no spacing aliphatic carbons. The lifetimes are signiticantly shorter than those of compounds having carbonyl substituents spaced farther from the chromophore. Gndole carboxylic acid and Gndole carboxylic acid each exhibit two S, conformer origins that have decidedly different lifetimes. These observations are consistent with the occurrence of fluorescence quenching due to charge transfer to the carbonyl. Further lifetime measure ments with the foregoing compounds deuterated at the acidic sites rule out excited-state proton transfer from these sites as an important quenching mechanism.