A Configurationally Tunable Perylene Bisimide Derivative‐based Fluorescent Film Sensor for the Reliable Detection of Volatile Basic Nitrogen towards Fish Freshness Evaluation

Comprehensive Summary Rapid and real‐time monitoring of food quality plays critical roles in the food industry and for the general public health. Herein, we specially synthesized a new perylene bisimide (PBI) derivative (PCB‐EpE) composed of two PBI units and a rigid o ‐carborane linker, which was further employed in constructing a conceptual fluorescent film sensor for evaluating fish freshness. Photophysical studies indicate that PCB‐EpE displays an open “Z‐type” molecular configuration in chloroform and a closed “Δ‐type” configuration in methyl cyclohexane. Comparatively, “Z‐type” molecular configuration possesses higher fluorescence quantum yield and is more sensitive toward volatile basic nitrogen (VBN). It is noteworthy that the film sensor responds in less than 1 s even in ambient humidity condition. High correlation between the content of total volatile basic nitrogen (TVB‐N) in evaluating fish freshness with different storage time and the fluorescence response is achieved. Detection limit of the film sensor toward trimethylamine as an example is lower than 2.6 mg/m 3 . Comprehensive sensing investigations demonstrate the rapid detection, strong anti‐interference capability and excellent reusability of the film sensor toward testing VBN. To our knowledge, this is the first report to accurately predict TVB‐N value for the evaluation of fish freshness using a fluorescent film sensor, showing great potential for real‐life applications.