A Benzimidazole-Based Fluorescent Probe for the Selective Recognition of Cobalt (II) Ions.

Cobalt, a rare element in the Earth's crust, is widely used in industries due to its hardness and antioxidant properties. It also plays a vital role in physiological functions, being a key component of vitamin B. However, excessive cobalt intake can cause health issues. Detecting cobalt ions, especially Co, in food is crucial due to potential contamination from various sources. Fluorescent probes offer high sensitivity, selectivity, a rapid response, and ease of use, making them ideal for the accurate and efficient recognition of Co in complex samples. In this context, a highly selective fluorescent probe, 2,2'-((3-(1H-benzo[d]imidazol-2-yl)-1,2-phenylene) bis(oxy)) bis(N-(quinolin-8-yl) acetamide) (), was synthesized using chloroacetyl chloride, 8-aminoquinoline, 2,3-dihydroxybenzaldehyde, and benzidine as raw materials for the recognition of Co. Probe can exhibit fluorescence alone in DMF. However, as the concentration of Co increased, Photoinduced Electron Transfer (PET) occurred, which quenched the original fluorescence of the probe. Probe shows better selectivity for Co than other ions with high sensitivity (detection limit: 3.56 μmol L), and the reaction reaches equilibrium within 30 min.