One-pot Synthesis of biologically active imidazole derivative as a fluorescent probe for the detection of Ce 4+ ion

The turn-off fluorescent probe 2-(trimethoxyphenyl)benzo[d]imidazole ( MBI ) was synthesized via a one-pot condensation of o-phenylenediamine with 2,4,5-trimethoxybenzaldehyde and confirmed by FT-IR, ¹ H & ¹³ C-NMR and Mass spectra). MBI exhibited strong fluorescence in the visible region and demonstrated notable antibacterial action against two Gram (+)ve and two Gram (-)ve bacteria, with a pronounced impact against Gram (-)ve bacteria. The Imidazole derivative (MBI) showed significant potency against E. coli and S. flexneri with MIC value 16µg/mL and MIC 32 µg/mL, respectively. Its fluorescence was selectively quenched by Ce ⁴⁺ via a photoinduced electron transfer (PET) mechanism, demonstrating high sensitivity and selectivity for Ce ⁴⁺ ion detection. The metal-ligand complex between MBI with Ce ⁴⁺ was determined to have 2:1 stoichiometry, validated by Benesi-Hildebrand procedure, with a binding constant of 1.17 × 10 ⁴ M ^− 1 and a Stern-Volmer quenching constant (K _sv ) of 7.8 × 10 ⁵ M ^− 1 .