Phenolacetyl Viologen as Multifunctional Chromic Material for Fast and Reversible Sensor of Solvents, Base, Temperature, Metal Ions, NH Vapor, and Grind in Solution and Solid State.

Electron-withdrawing/coordinating -phenolacetyl-substituted viologen can act as a visual sensor for solvents, bases, and temperature in organic solvents. Due to chelating phenolacetyl groups, this viologen can coordinate to Fe(III), Cu(II), and ZnCl in aqueous and DMF solutions. Interestingly, this viologen can respond to temperature, grind, and NH vapor in its solid state. Stimuli response is visible, fast, and fully reversible in air at room temperature. The color change is attributed to the enolic and/or free radical structure. This is the most versatile chromic material that responds to chemical and physical stimuli in both solution and solid state.