Aggregation-Induced Emission of a Two-Dimensional Covalent Organic Framework for Molecular Recognition in Quantitative Metrics

Fluorescent porous materials have been intensively examined owing to their versatile applications in molecular recognition and chemical sensing. Although many studies on luminescent two-dimensional (2D) covalent organic frameworks (COFs) for chemical sensing applications have been reported, precise linear control of the aggregation-induced luminescence effects in 2D COFs has been rarely achieved. Hereby, a highly crystalline 2D COF material bearing a tetraphenylethylene (TPE) molecule as a molecular rotor with a responsive fluorescence behavior is reported. Due to the varying extent of motion regulation of the TPE rotor with different volatile organic compounds (VOCs), the as-obtained fluorescent 2D COFs exhibit excellent sensitivity and selectivity in the qualitative and quantitative analysis of volatile organic compounds (VOCs). Notably, the fluorescence intensity derived from the aggregation-induced emission (AIE) is in a linear relationship with VOCs across a wide concentration range (0–3.0 × 103 mM), indicating their potential as effective VOC detectors.