Rational design of piperidine functionalized boron-dipyrromethene as fluorescent chromoionophore for ion-selective optodes

Piperidine functionalized boron-dipyrromethene (BODIPY) derivative was developed as the first phenylamino BODIPY type of pH indicators exhibiting fluorescence enhancement in the process of the deprotonation. The piperidine units on BODIPY core not only provided the excitation and emission at visible wavelength, but also changed the energy level of excited fluorophore inducing an oxidative PET process upon deprotonation. The probe was further applied to prepare fluorescence turn-on cation selective optodes based on ion-exchange sensing mechanism, which revealed fluorescence enhancement in the presence of target metal ion. For the model ion, Pb2+, the proposed sensor exhibited the linear response to Pb2+ in the range of 10−5-10−1 M with the detection limit of 10−6 M. The excellent sensitivity and selectivity of Pb2+ optode suggested that the new fluorescent chromoionophore was compatible and fully functional in ionophore-based polymeric optode.