Novel spiropyran fluorescent probes based on ESIPT and ICT: pH Response & Cyanide Detection

Zhou, Xu; Zhang, Qing; Lin, Qiancai; Liang, Xi; Zhang, Chunxue; Zhang, Ze; Shen, Lingyi; Yang, Xianjiong; Xu, Hong; Redshaw, Carl; Zhang, Qi Long

Abstract

Due to the wide application of cyanide in the fields of steel, petroleum and pharmaceutical chemicals and its high lethality to living organisms, the development of new materials that can detect CN− in a fast, simple and sensitive way is very necessary. Based on excited state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) mechanisms, we constructed a novel spiropyran fluorescent probes (E)-3-(2-(2-(5-(benzo[d]thiazol-2-yl)-4′-(diphenylamino)-4-hydroxy-[1,1′-biphenyl]-3-yl)vinyl)-3,3-dimethyl-3H-indol-1-ium-1-yl)propane-1-sulfonate (TPTC) by integrating triphenylamine, benzothiazole and hemicarbocyanine structures. It was shown that TPTC has ESIPT and ICT properties, possessing a large Stokes shift (168 nm). Under the condition of DMSO:PBS=3:7, pH=7, after adding CN− to the probe, the fluorescence emission at 530 nm was greatly enhanced, and the fluorescence intensity was gradually strengthened with the increase of the amount of CN−, which had a good linear relationship, and exhibited fluorescence “turn-on”. The fluorescence “turn-on” recognition of CN− was demonstrated with high specificity, strong anti-interference ability and low detection limit (146.00 nM). The sensing mechanism was demonstrated by HRMS and 1H NMR. It was also successfully applied to the spiking and recovery of CN− in laboratory water and natural reservoir water, with recoveries of 101%∼109% in laboratory water and 108%∼116% in natural reservoir water testing. Fluorescence sensing of CN− was achieved in bitter almond, serum samples and cells. In addition, the probe has a pH-responsive property, and the fluorescence at 530 nm was gradually enhanced with the increase of pH, with a good linearity in the pH=10-12 range.

Citation

Zhou, X., Zhang, Q., Lin, Q., Liang, X., Zhang, C., Zhang, Z., Shen, L., Yang, X., Xu, H., Redshaw, C., & Zhang, Q. L. (2025). Novel spiropyran fluorescent probes based on ESIPT and ICT: pH Response & Cyanide Detection. Journal of molecular structure, 1322(2), Article 140429. https://doi.org/10.1016/j.molstruc.2024.140429

• Journal Article Type: Article
• Acceptance Date: Oct 15, 2024
• Online Publication Date: Oct 18, 2024
• Publication Date: Feb 15, 2025
• Deposit Date: Nov 15, 2024
• Publicly Available Date: Oct 19, 2025
• Journal: Journal of Molecular Structure
• Print ISSN: 0022-2860
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 1322
• Issue: 2
• Article Number: 140429
• DOI: https://doi.org/10.1016/j.molstruc.2024.140429
• Keywords: Cyanide detection; pH response; Fluorescent probe; Spiropyran; ESIPT and ICT
• Public URL: https://hull-repository.worktribe.com/output/4908184