Photochemical & Photobiological Sciences 2003-02-01

Intra- and intermolecular fluorescence quenching of N-activated 4,5-dimethoxyphthalimides by sulfides, amines, and alkyl carboxylates.

Axel G Griesbeck, Stefan Schieffer

Index: Photochem. Photobiol. Sci. 2(2) , 113-7, (2003)

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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.