A Coumarin–Hemicyanine Deep Red Dye with a Large Stokes Shift for the Fluorescence Detection and Naked-Eye Recognition of Cyanide

Li, Dongmei; Peng, Senlin; Zhou, Xu; Shen, Lingyi; Yang, Xianjiong; Xu, Hong; Redshaw, Carl; Zhang, Chunlin; Zhang, Qilong

Abstract

In this study, we synthesized a coumarin–hemicyanine-based deep red fluorescent dye that exhibits an intramolecular charge transfer (ICT). The probe had a large Stokes shift of 287 nm and a large molar absorption coefficient (ε = 7.5 × 105 L·mol−1·cm−1) and is best described as a deep red luminescent fluorescent probe with λem = 667 nm. The color of probe W changed significantly when it encountered cyanide ions (CN−). The absorption peak (585 nm) decreased gradually, and the absorption peak (428 nm) increased gradually, so that cyanide (CN−) could be identified by the naked eye. Moreover, an obvious fluorescence change was evident before and after the reaction under irradiation using 365 nm UV light. The maximum emission peak (667 nm) decreased gradually, whilst the emission peak (495 nm) increased gradually, which allowed for the proportional fluorescence detection of cyanide (CN−). Using fluorescence spectrometry, the fluorescent probe W could linearly detect CN− over the concentration range of 1–9 μM (R2 = 9913, RSD = 0.534) with a detection limit of 0.24 μM. Using UV-Vis spectrophotometry, the linear detection range for CN− was found to be 1–27 μM (R2 = 0.99583, RSD = 0.675) with a detection limit of 0.13 μM. The sensing mechanism was confirmed by 1H NMR spectroscopic titrations, 13C NMR spectroscopy, X-ray crystallographic analysis and HRMS. The recognition and detection of CN− by probe W was characterized by a rapid response, high selectivity, and high sensitivity. Therefore, this probe provides a convenient, effective and economical method for synthesizing and detecting cyanide efficiently and sensitively.

Citation

Li, D., Peng, S., Zhou, X., Shen, L., Yang, X., Xu, H., Redshaw, C., Zhang, C., & Zhang, Q. (2024). A Coumarin–Hemicyanine Deep Red Dye with a Large Stokes Shift for the Fluorescence Detection and Naked-Eye Recognition of Cyanide. Molecules, 29(3), Article 618. https://doi.org/10.3390/molecules29030618

• Journal Article Type: Article
• Acceptance Date: Jan 25, 2024
• Online Publication Date: Jan 27, 2024
• Publication Date: Feb 1, 2024
• Deposit Date: Feb 17, 2024
• Publicly Available Date: Feb 20, 2024
• Journal: Molecules
• Electronic ISSN: 1420-3049
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 29
• Issue: 3
• Article Number: 618
• DOI: https://doi.org/10.3390/molecules29030618
• Keywords: Coumarin–hemicyanine; Deep red fluorescent dye; Large Stokes shift; Cyanide
• Public URL: https://hull-repository.worktribe.com/output/4548906