HOW IMPORTANT IS THE QUENCHING INFLUENCE OF THE TRANSITION-METAL IONSIN THE DESIGN OF FLUORESCENT PET SENSORS

The fluorescence response of a nitrobenzoxadiazole fluorophore, attach ed to an amine receptor through a spacer unit, in the presence of a st rongly quenching metal ion Cr3+ is reported, It is shown that the supr amolecular system exhibits considerable enhancement of fluorescence in the presence of the metal ion, despite the quenching nature of the me tal ion. This observation is rationalised in terms of the excited stat e lifetime of the fluorophore and the possible implication of this res ult in the design of fluorosensors for the quenching transition metal ions is discussed. (C) 1998 Elsevier Science B.V. All rights reserved.