Synthesis and selective recognition of Gd ³⁺ ions by di-schiff base amine containing methylbenzaldehyde fluorescent probe

Abstract A novel fluorescent probe (L), derived from a pyridine bisamide-based p-methylbenzaldehyde Schiff base, was synthesized by the condensation of N,N’- bis(2- aminoethyl)- 2,6- pyridinedicarboxamide and p- methylbenzaldehyde. The structure of probe L was confirmed by IR and 1 H NMR spectroscopy, as well as molecular mass determination. The probe demonstrated high selectivity toward Gd 3+ ions, exhibiting significant fluorescence quenching upon binding. Job’s plot and fluorescence titration analysis revealed a 1:1 stoichiometry for the L–Gd 3+ complex, with an association constant (Ka) of 2.8259 × 10 8 M −1 . The detection limit for Gd 3+ was determined to be 1.3312 × 10 −5 mol/L within a linear range of 0–200 μM. These results suggest the potential applicability of probe L for trace detection of Gd 3+ ions.