Dual functioning dioxo-molybdenum complex of an amide-based imine derivative: fluorescence recognition of Zr(iv) and Y(iii) with catecholase-like activity.

An amide-based imine derivative, namely, 2,4-dihydroxy-benzoic acid (2-hydroxy-naphthalen-1-ylmethylene)-hydrazide [DBANP], is prepared by the condensation of 2,4-dihydroxybenzoic acid hydrazide (DBA) and 2-hydroxynaphthaldehyde. Further, DBANP is employed to prepare the corresponding Mo(vi) complex (DBANPM), the structure of which is established by different spectroscopic techniques and authenticated by single-crystal X-ray diffraction (SC-XRD) analysis. Notably, DBANPM selectively recognizes ZrO2+ and Y3+ in two different media, namely, aqueous ethanol and ethyl acetate, via the generation of sky-blue emission. The binding constant values for ZrO2+ and Y3+ are 7.9 × 104 M-1 and 7.2 × 104 M-1, respectively. The displacement of Mo(vi) from DBANPM by ZrO2+ and Y3+ is responsible for this sky-blue emission. DFT studies substantiate the interactions and unveil the associated orbital energy parameters. Silica-immobilized DBANPM allows the solid-phase extractive recovery of ZrO2+, while the solvent extraction of Y3+ from water to ethyl acetate is achieved using DBANPM. A DBANPM-impregnated paper strip allows for the low-cost, facile and instant fluorescence detection of Y3+ in real samples. DBANPM also exhibits a catechol oxidase-like activity.