<p>A noble highly selective, sensitive and SmA mesogenic dipeptide-based Schiff base ligand (HL) was synthesized and characterized using various instrumental and analytical techniques. The Schiff base ligand functions as a potent fluorescent chemosensor for the dual detection of Cd²⁺ and Zn²⁺ metal ions with the detection limits of 2.02 nM and 2.68 nM, respectively. Job’s plot analysis revealed 2:1 stoichiometric ratio between the probe and the metal ions, with binding constant value of 3.25 × 10⁶ M^− 1 for Zn²⁺ and 5.20 × 10⁶ M^− 1 for Cd²⁺. The probe showed reversibility nature over four cycles through alternate addition of Zn²⁺/ Cd²⁺ and EDTA, exhibiting distinct off-on-off fluorescence, enabling construction of three molecular logic gates. The probe effectively detected Zn²⁺ and Cd²⁺ in real water samples over a broad pH range. The DFT study of the Schiff base and its complexes with Zn²⁺ and Cd²⁺ were performed using LanL2DZ and 6-31G(d, p) basis set with the hybrid correlation B3LYP to ascertain the optimized geometry.</p>