A Hemicyanine-Based Highly Sensitive and Selective Near-Infrared Fluorescent Probe for Fe³⁺ in Aqueous Media

Ferric ion is widely distributed in human cells and an important component of hemoglobin, which can promote the transportation of blood in the human body. Its ability to bind with oxygen is essential for participating in oxidation reactions and enzymatic reactions. Deficiency of iron (III) and excessive accumulation of iron in the blood can cause many health problems in the body, such as anemia, loss of appetite, fibrosis, reduced work routines, and decreased immunity. As a fluorescent dye, cyanine has the advantages of high fluorescence quantum yield, good optical and chemical stability, excitation and emission wavelengths in the near-infrared region, high molar extinction coefficient, and small influence on pH variation. It is a fluorescent dye that modern scholars choose more. A new near-IR hemicyanine derivative bearing 1,3-dithiane moiety was developed as an efficient fluorescence probe 1 for the detection of Fe³⁺ in aqueous medium (THF/H₂O, 1:1, v:v). This near-IR fluorescence probe 1 exhibits high sensitivity and selectivity toward Fe³⁺ sensing with detection limit of 0.5 μM under lager scope of pH value (pH = 2-12).