An off–on fluorescence sensor based on a hydrogen-bonded organic framework for the detection of ascorbic acid

Ascorbic acid (AA) is essential to human health, and accurate detection of AA content in food and drugs is necessary for disease monitoring. In this study, a hydrogen-bonded organic framework (HOF-TCBPA) was constructed with tris[(4-carboxyl)biphenyl]amine (H₃TCBPA) as the only raw material, and Cu²⁺ was added for modification to develop a simple off-on fluorescence sensor (HOF-TCBPA/Cu²⁺) for detecting AA. Cu²⁺ can quench the fluorescence emission of HOF-TCBPA. However, in the presence of AA, the fluorescence emission of HOF-TCBPA was restored, resulting in an off-on response mechanism. The results indicated that the linear range for detecting AA concentration utilizing HOF-TCBPA/Cu²⁺ was 0.1-1.0 mmol L^-1, with a detection limit of 0.076 mmol L^-1. This work introduces a new platform for developing off-on fluorescence sensors using HOF/metal ions.