A pH switchable hydrophilic fluorescent BODIPY sodium disulfonate for Fe3+ multicolor detection: Experimental and DFT studies

Abstract

BODIPY-based chemosensors are widely used owing to merits like good selectivity, high fluorescence quantum yield, and excellent optical stability. As such, a pH-switchable hydrophilic fluorescent probe, BODIPY-PY-(SO3Na)2, was developed for detection of Fe3+ ion in aqueous solutions. BODIPY-PY-(SO3Na)2 revealed strong fluorescence intensity and was responsive to pH value in the range of 6.59–1.96. Additionally, BODIPY-PY-(SO3Na)2 showed good selectivity and sensitivity towards Fe3+. A good linear relationship for Fe3+ detection was obtained from 0.0 μM to 50.0 μM with low detecting limit of 6.34 nM at pH 6.59 and 2.36 nM at pH 4.32, respectively. The response to pH and detection of Fe3+ induced obvious multicolor changes. BODIPY-PY-(SO3Na)2 can also be utilized to quantitatively detect Fe3+ in real water sample. Different mechanisms of Fe3+ detection at investigated pH values were unraveled through relativistic density functional theory (DFT) calculations in BODIPY-PY-(SO3Na)2 and experiments of coexisting cations, anions and molecules. These results enabled us to gain a deeper understanding of the interactions between BODIPY-PY-(SO3Na)2 and Fe3+ and provide valuable fundamental information for design of efficient multicolor chemosensors for Fe3+ as well.