Dual-functional fluorescent probes: Cyanide sensing and forensic fingerprint detection using imidazole derivatives

The development of a multifunctional fluorescent probe, capable of detecting harmful ions and visualizing latent fingerprints, advances analytical science by streamlining environmental monitoring and forensic analysis. Its dual functionality reduces procedural complexity and equipment needs, offering practical value in environmental protection, forensic analysis, and public safety applications. In this study, we synthesized a series of fluorescent molecules based on 1-methyl-4,5-diphenylimidazole conjugated with 2-phenylacetonitrile and its chloro- and nitro-substituted derivatives (DPIH, DPICl, and DPINO₂). Utilizing the electron-donating nature and aggregation-induced emission (AIE) characteristics of 4,5-diphenylimidazole, we introduced electron-withdrawing groups to modulate intramolecular charge transfer (ICT) and fine-tune their fluorescence responses. Among the synthesized compounds, DPICl demonstrated excellent selectivity and sensitivity toward cyanide (CN^-), with a detection limit of 0.66 μM, significantly below the World Health Organization's limit for CN^- in drinking water. It also successfully detected cyanide in real food samples such as sprouted potatoes, apple seeds, and plum seeds, confirming its practical utility in real-world environmental and food safety applications. Beyond anion sensing, DPICl exhibited strong fluorescence in the solid and aggregated states, making it suitable for latent fingerprint detection. Its hydrophobic nature promoted effective interaction with fingerprint residues, producing clear and detailed ridge patterns essential for precise forensic identification. These findings highlight the remarkable versatility of DPICl, showcasing its effectiveness across diverse fields such as environmental monitoring and forensic analysis. With excellent sensing capabilities and multifunctional design, it holds great promise for next-generation applications in safety, detection, and diagnostic technologies.