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

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-(SONa), was developed for detection of Fe ion in aqueous solutions. BODIPY-PY-(SONa) revealed strong fluorescence intensity and was responsive to pH value in the range of 6.59-1.96. Additionally, BODIPY-PY-(SONa) showed good selectivity and sensitivity towards Fe. A good linear relationship for Fe 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 Fe induced obvious multicolor changes. BODIPY-PY-(SONa) can also be utilized to quantitatively detect Fe in real water sample. Different mechanisms of Fe detection at investigated pH values were unraveled through relativistic density functional theory (DFT) calculations in BODIPY-PY-(SONa) and experiments of coexisting cations, anions and molecules. These results enabled us to gain a deeper understanding of the interactions between BODIPY-PY-(SONa) and Fe and provide valuable fundamental information for design of efficient multicolor chemosensors for Fe as well.