NCS-catalyzed synthesis of 2,4,5-triaryl-1H-imidazole and its selective detection of iron ions

In this study, an efficient synthesis of 2,4,5-trisubstituted imidazoles was developed via cyclocondensation starting from o -dione, substituted aromatic aldehyde and ammonium acetate using catalyst NCS, and was characterized by HR-MS, FT-IR, 1 H and 13 C NMR spectroscopy. A novel fluorescence sensor 4-(1 H -phenanthro[9,10- d ]imidazol-2-yl)- N, N -diphenylaniline ( 3bd ) was discovered for the detection of Fe 3+ ions. The probe 3bd exhibited strong blue radiation in solution. In the presence of Fe 3+ ions, a significant fluorescence change of blue light to green light was observed in the EtOH/H 2 O (4/1, v/v) solution of 3bd (Ag + , Al 3+ , Ba 2+ , Ca 2+ , Cd 2+ , Co 2+ , Cr 3+ , Cu 2+ , Fe 2+ , Fe 3+ , Hg 2+ , Mg 2+ , Mn 2+ , Pb 2+ , Sr 2+ , Zn 2+ ). The limits of detection of probe 3bd for Fe 3+ ions was calculated to be as low as 0.70 μ M, and it had excellent anti-interference ability. The probe 3bd complexed with Fe 3+ ions at 1:1, and the complexation constant was 3.93 × 10 4 M −1 . The probe 3bd realized the detection of Fe 2+ oxidation to Fe 3+ , and the pH showed fine stability in the environment between 4.0–7.0, which ensured its potential application prospects. It also showed good reversibility upon addition of EDTA. Furthermore, the viability of 3bd to Fe 3+ had practical application in live cell imaging.