Fabrication and sensing properties of phenolphthalein based colorimetric and turn–on fluorogenic probe for CO32− detection and its living–cell imaging application

Herein, an easy assembled colorimetric and ''turn–on'' fluorescent sensor (probe P4SC) based on phenolphthalein was developed for carbonate ion (CO32−) sensing in a mixture of EtOH/H2O (v/v, 80/20, pH = 7, Britton–Robinson buffer) media. The probe P4SC demonstrated high sensitive and selective monitoring toward CO32− over other competitive anions. Interaction of CO32− with the probe P4SC resulted in a significant increment in emission intensity at λem = 498 nm (λex = 384 nm) due to the strategy of blocking the photo induced electron transfer (PET) mechanism. 1H NMR titration and Job's methods, as well as the theoretical study were carried out to support the probable stoichiometry of the reaction (1:2) between P4SC and CO32−. The binding constant of the probe P4SC with CO32− was calculated as 2.56 × 1010 M−2. The probe P4SC providing rapid response time (~0.5 min) with a satisfactorily low detection limit (14.7 nM) may be useful as a valuable realistic sensor. The imaging studies on the liver cancer cells (HepG2) shows the great potential of the probe P4SC for the sensation of intracellular CO32− anions. Furthermore, the satisfactory recovery and RSD values obtained for water application confirming that the probe P4SC could be applied to sensing of CO32− ion.