Design of a large Stokes shift ratiometric fluorescent sensor with hypochlorite detection towards the potential application as invisible security ink.

Hypochlorite (ClO-) as a well-known highly reactive oxygen species (ROS), is widely used as preservative and household disinfectant in daily life. Although many fluorescence imaging sensors for ClO- have been reported, the development of ClO- ratio fluorescence sensors with large Stokes shift is still quite limited. This sensor shows obvious benefits including minimizing environmental intervention and improving signal-to-noise ratio. In the present project, we report an innovative conjugated pyrene-based system, 1-B, as a chlorine fluorescence sensor. The detector exhibits ratio detection performance, large Stokes and emission shifts. Furthermore, the system has desired sensitivity as well as selectivity for ClO-. Based on these excellent properties, the sensor 1-B was successfully used as ink to encrypt patterns and anti-counterfeiting information through inkjet printing technology. Compared with the existing probes, the probe shows some superior characteristics, which provides a promising tool for exploring the role of ClO- response sensor in the field of anti-counterfeiting.