Colorimetric probes to H2S based on changes in geometric configuration of perylene diimine radical π-dimers and muscle food freshness monitoring

• The PDI radical π-dimer shows the changes in spectra based on configuration change. • The solution or films of π-dimer have high sensitive colorimetric response to H 2 S. • Colorimetric performance of the π-dimer to H 2 S shows high selectivity. • The π-dimer film achieve real-time monitoring muscle food spoilage. The food freshness monitoring system based on the trace gases released by food spoilage is an important focus in the field of food chemistry. Recently, we discovered a perylene diimide anionic radical π-dimer that achieved solvatochromism and pH discoloration based on the changes in geometry structures. Herein, by controlling the geometry structures of this radical π-dimer, we performed trace H 2 S detection based on the changes in color and fluorescence, achieving a lowest detection limits of 0.044 µM in N, N-dimethylformamide. Additionally, colorimetric films based on these radical π-dimer/silica gel exhibited high sensitivity to H 2 S, and achieved real-time monitoring muscle food spoilage with visible color changes from white to grey within 2.5 h. We believe that these environmental sensitive radical derivatives can serve as candidate materials for colorimetric monitoring of muscle food freshness.