A Phenanthraquinone Based Fluorescent Probe for Sequential Detection of Cu2+ and SO32−

Herein we report the selective detection of Cu2+ and SO3 2− by phenanthraquinone thiosemicarbazone (PQTSC) chemosensor. The chemosensor is efficient in detecting Cu2+ over other metal ions, while the PQTSC-Cu2+ complex selectively sense SO3 2− over other anions. On addition of Cu2+ to the receptor solution, quenching of emission intensity is observed by 16 folds and upon gradual addition of SO3 2− to this solution, the emission intensity increases and the maxima is regained. The limit of detection for Cu2+ detection calculated from fluorescence titration is 1.06 × 10−8 M and the association constant of PQTSC with Cu2+ is found to be 2.18 × 105.