A new salicylaldehyde-based sensor N'-(5-bromo-2-hydroxybenzylidene)-4-methylbenzohydrazide (P4) was designed, and its sensing ability towards various metal ions was assessed using UV-visible spectroscopy. The structure of P4 was spectroscopically characterized by UV-Visible, Infrared, ¹H-NMR, ¹³C-NMR spectroscopy and mass spectrometry. UV-Visible absorption spectral study showed selective sensing ability of P4 for Cd²⁺ and Ni²⁺ ions in presence of diverse transition metal ions. The results revealed that the detection limit for Cd²⁺ and Ni²⁺ was 3.14 µM and 0.92 µM, respectively. Moreover, the compound P4 was fully implemented for detection of Cd²⁺ and Ni²⁺ in simulated samples.

Proficient routes were devised for coupling different aromatic/aliphatic acids with amines to form amide linkage using various catalysts. Under the optimized reaction conditions, highest conversion was possible without formation of any by-products. All synthesized compounds were purified using column chromatography and characterized by mass spectrometry, nuclear magnetic resonance spectrometry and liquid chromatography-mass spectrometric analysis.