Reversible photodynamic chloride-selective sensor based on photochromic spiropyran

We report here for the first time on a reversible photodynamic bulk optode sensor based on the photoswitching of a spiropyran derivative (Sp). The photoswitching of Sp induces a large basicity increase in the polymeric phase, which triggers the extraction of Cl(-) and H(+). Cl(-) is stabilized by a lipophilic chloride-selective ionophore inside the membrane, while H(+) binds with the open form of Sp and induces a spectral change, hence providing the sensor signal. The system was studied with spectroscopic and electrochemical methods.