Development of a Comprehensive Undergraduate Organic Chemistry Experiment within a CDIO-PBL Framework: Synthesis and Fluorescence Sensing Applications of 3-Cyano-7-diethylaminocoumarin

In response to the growing demand for interdisciplinary and innovative talent in chemistry education, this study developed a comprehensive undergraduate organic chemistry experiment within the CDIO-PBL framework. Centered on the synthesis and application of 3-cyano-7-diethylaminocoumarin as a high-performance fluorescent probe for cyanide detection, the project integrates molecular design, green synthesis, structural characterization, and functional evaluation. The dual-cycle teaching model combines PBL-driven inner cycles guiding the Conceive–Design–Implement–Operate process with CDIO-aligned outer cycles that promote reflection and continuous improvement. Experimentally, students achieved up to an 85% yield using a choline chloride/brine catalytic system and confirmed the product structure by 1H/13C NMR and HRMS, while the resulting probe demonstrated strong fluorescence, high sensitivity for CN– (LOD < 0.05 μM), and rapid response (<100 s). They also fabricated functional sensing devices for smartphone-assisted CN– detection in real food samples. Rubric-based evaluation of students’ laboratory reports showed Proficient-to-Expert performance (average score = 4.4 ± 0.1) and cognitive advancement to the Relational-to-Extended Abstract level on the SOLO taxonomy. These outcomes demonstrate that the iterative CDIO-PBL model effectively links theoretical understanding with practical creativity, fostering integrated engineering thinking and interdisciplinary problem-solving abilities.