The use of conjugated polymers for sensor applications continues to be the subject of intense research. In addition to their use as electronic conductors, they have been exploited as active sensing elements by coupling ligands to the backbone. In this approach, binding of an analyte results in physical distortions or changes in electron density, thereby altering conductivity. Poly(aniline), in particular, has received a great deal of attention due to its proton coupled redox chemistry and its resulting pH-dependent properties. For example, poly(aniline) has been used as a pH electrode and has been coupled to reactions that generate or consume protons to create sensors. Herein, we report a new strategy that exploits the inductive effect of reactive substituents on the pK_a of poly(aniline) to produce active sensing elements
