Abstract:

Chromic materials are widely used in aerospace, energy and chemical industries, food, national defense, and scientific research. Viologen compounds (N-substituted 4,4’-bipyridine quaternary ammonium salts) are an important class of chromic materials that exhibit rich chromic properties under external stimuli, such as light, electricity, and temperature. This innovative fundamental chemistry experiment was designed based on scientific frontier results of viologen compounds. The o-hydroxyacetophenone substituted viologen was synthesized, and its solvatochromism, thermochromism, and reversible NH₃ vapor sensor in the solid state were studied, aiming to stimulate students’ curiosity and desire for exploration, cultivate students’ interest in chemistry, broaden their horizons, and improve their chemistry cognition. The raw materials for this experiment are simple and easy to obtain, the synthesis method is simple, and the reaction time is short with high yield and good repeatability. All chromic phenomena are fast, highly sensitive, and can be directly observed with the naked eye, which aids the application of these experiments.

Key words: Chromic materials, Viologen derivative, Visible, Ammonia sensor