title: Intra- and intermolecular fluorescence quenching of N-activated 4,5-dimethoxyphthalimides by sulfides, amines, and alkyl carboxylates.
abstract: The fluorescent 4,5-dimethoxyphthalimides 1-10 were applied as sensors for intra- and intermolecular photoinduced electron transfer processes. Strong intramolecular fluorescence quenching was detected for the thioether 2 and the tertiary amine 3. The fluorescence of the carboxylic acids 4-7 is pH-dependent accounting for PET-quenching of the singlet excited phthalimide at pH > pKs. At low pH, chromophore protonation might contribute to moderate fluorescence quenching. The arylated phthalimides 9 and 10 show remarkable low fluorescence independent of pH and substituent pattern. Intermolecular fluorescence quenching was detected for the combinations of 1 with dimethyl sulfide, and 1 with triethylamine but not with metal carboxylates.
authors.affiliation: Institute of Organic Chemistry University of Cologne, Greinstr. 4, D-50939 Köln, Germany. griesbeck@uni-koeln.de
authors.forename: Axel G
authors.initials: AG
authors.lastname: Griesbeck
authors.forename: Stefan
authors.initials: S
authors.lastname: Schieffer