Cyanine dyes have been widely used for fluorescent sensory applications in both industry and academia. However, they are limited by drawbacks such as a small Stokes shift (up to 20nm) and concentration quenching effect.
Scientists in China have now designed a red emissive hemicyanine dye that overcomes these drawbacks. The dye possesses a large Stokes shift (>185nm) and shows different colours and intensities over a broad pH range (pH 5-14).
The acid/base-switched red/blue emission transition is reversible and can last for many cycles.
Link to journal article
An AIE-active hemicyanine fluorogen with stimuli-responsive red/blue emission: Extending the pH sensing range by “switch + knob” effect
S Chen et al
Chem. Sci., 2012, DOI: 10.1039/c2sc01108e
