A novel phenolphthalein-based fluorescent sensor for Al sensing in drinking water and herbal tea samples.

In this study, 3,3-bis(4-hydroxy-3-((E)-((4-hydroxyphenyl)imino)methyl) phenyl)isobenzofuran-1(3H)-one (HMBP) was designed as a ''turn-on″ fluorogenic chemosensor to detect Al. Studies were performed in CHOH-HEPES (v/v, 9/1, pH 7.0) media at λ = 475 nm. The LOD value was found to be 0.113 µM. The stoichiometric ratio of HMBP-Al was determined as 1:2 by Job's plot and ESI-MS as well as H NMR titration. The binding constant of chemosensor HMBP with Al from the Benesi-Hildebrand equation was determined to be 1.21 × 10 M. The quantum (Φ) yields were obtained as 0.040 and 0.775 for the chemosensor HMBP and HMBP-Al, respectively. The response of the chemosensor HMBP towards Al was attributed to the strategies of blocking the photo-induced electron transfer (PET) and CN isomerisation mechanisms. Finally, the sensing of the chemosensor HMBP for the determination of Al in real food samples, drinking waters and herbal teas, were employed.