Fluorescence Quenching of Two meso-Substituted Tetramethyl BODIPY Dyes by Fe(III) Cation

Ferric ion (Fe(III)) is a biologically and environmentally relevant cation so that its analysis in environmental and biological samples is often required. Borodiazaindacenes (BODIPYs) are known for their good photophysical properties; however, there are few BODIPY-based Fe(III) sensors reported. Herein, we show the characterisation of two BODIPY dyes whose fluorescence emission is diminished by such cation. Both "turn-off" probes, a catecholyl-substituted BODIPY and a pyridyl-substituted BODIPY, were synthetically obtained and an initial screening showed a relatively good specificity for Fe(III) when compared to other cations. Catecholyl-substituted BODIPY was more sensitive to Fe(III), however, with a pH-dependent analytical performance and low brightness. On the other hand, pyridyl-substituted BODIPY was very bright and its analytical performance was apparently pH-independent, however, it was less sensitive to the analyte. In conclusion, we show herein the obtainment and characterisation of two probes with promising analytical value in the analysis of Fe(III). (AU)