A 2-mercaptobenzimidazole-based emissive Cu(I) complex for selective determination of iodide with large Stokes shift

A Cu(I) complex of 2-mercaptobenzimidazole (R1) was synthesized and characterized using single-crystal X-ray diffraction. Complex R1 showing strong emission at 598 nm serves as a sensor for iodide determination. Upon addition of iodide to a solution of complex R1, a reduction in emission intensity by aggregation-caused quenching (ACQ) was observed, with a large Stokes shift. The limit of detection (LOD) of complex R1 was estimated to be 14 ± 1.5 nM. Complex R1 proved to be reusable by extracting the iodide ions with silver nitrate. The advantages of using complex R1 as a sensor for iodide include low LOD and emission at long wavelengths, which eliminate the interference caused by short-wavelength emissive impurities.