A Highly Sensitive Bimodal Detection of Amine Vapours Based on Aggregation Induced Emission of 1,2‐Dihydroquinoxaline Derivatives

The detection of food spoilage is a major concern in food safety as large amounts of food are transported globally. Direct analysis of food samples is often time‐consuming and requires expensive analytical instrumentation. A much simpler and more cost‐effective method for monitoring food fermentation is to detect biogenic amines generated as a by‐product during food decomposition. In this work, a series of 1,2‐dihydroquinoxaline derivatives (DQs) with aggregation‐induced emission (AIE) characteristics were synthesised and their protonated forms, that is, H + DQs, can be utilised for the sensitive detection of biogenic amines. For example, upon exposure to amine vapours, deprotonation occurs that converts the red‐coloured, non‐emissive H + DQ2 back to its yellow‐coloured, fluorescent parent form. The bimodal absorption and emission changes endow the system with high sensitivity, capable of detecting ammonia vapour at a concentration of as low as 690 ppb. Taking advantage of this, H + DQ2 was successfully applied for the detection of food spoilage and was established as a robust and cost effective technique to monitor food safety.