Design and synthesis of (2-amino-5-nitrophenyl) (phenyl)methanone-based azo dyes for selective Ni2+ sensing and their anticancer activity

Abstract A series of azo dye derivatives (3a–3e) derived from 2-amino-5-nitrobenzophenone were synthesized, structurally characterized and confirmed. Density functional theory calculations were performed to understand the electronic properties of the synthesized molecules. The chemosensing ability of selected compounds (3c–3e) toward divalent metal ions was investigated. Among them, compound 3d exhibited a distinct and selective response toward Ni 2+ ions, accompanied by the formation of a new absorption band, indicating complex formation. Spectroscopic studies established a 2:1 ligand-to-metal stoichiometry with a high association constant (K a = 2.97 × 10 5 M −1 ), along with a low detection limit of 1.40 × 10 −7 M. The sensing performance is comparable to many reported colorimetric Ni 2+ chemosensors offering high selectivity and sensitivity. In addition, biological evaluation against HepG2 cells demonstrated significant cytotoxic activity for compound 3d (IC 50 = 40.65 µg/mL). These results demonstrate that azo-based compounds exhibit strong potential for selective metal ion sensing and biological activity, providing an efficient approach for applications in environmental monitoring and biomedical research.