An oxacalix[4]arene-Ce(III) complex viz. L–Ce(III) has been introduced for the selective detection of As(V) and Cr(VI) oxyanions in aqueous medium. The binding mode of L–Ce(III) + AsO₄ ³⁻/CrO₄ ²⁻ was completely investigated with fluorometric titration, time resolve fluorescent decay and FTIR analyses. Photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) play an important role in the sensing of these oxyanions. The characteristic fluorescence of the L–Ce(III) complex has been quenched by AsO₄ ³⁻ and CrO₄ ²⁻ through cascading the ligating sites. Cyclic voltammetry (CV) experiments with various scan rates suggest that the electrochemical processes on the electrodes were controlled by diffusion. Both the analytes exhibit a lower limit of detection (LOD) below their standard EPA permissible limits. Moreover, the probe successfully detects the oxyanions in environmental real samples with excellent recovery ranging from 97 to 101%.

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