Simple turn-on fluorescent chemosensor for ultrafast and highly selective trace-level detection of Cu2+ ions in aqueous solutions

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2024-01, Vol.305, p.123555, Article 123555
• Main Authors: Park, Seonmin, Bong, So Yeon, Sharma, Shilpa, Singh, Narinder, Park, Yea-In, Park, Junsoo, Ok Jang, Doo
• Format: Article
• Language: English
• Subjects: Chemosensors; Cu(II) ions; Fluorescence; Trace-level detection; Ultrafast detection
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2023.123555

[Display omitted] •A benzimidazole-based probe BIPMA was synthesized for detecting Cu2+ ions.•BIPMA exhibits a fluorescence “turn-on” mechanism upon binding with Cu2+ ions.•BIPMA can estimate Cu2+ concentrations in the nanomolar range.•The response time of BIPMA toward Cu2+ ions is ultrafast.•BIPMA estimates Cu2+ ion concentration in real water samples and image living cells. A benzimidazole-based probe, BIPMA (2-(1H-benzo[d]imidazol-2-yl)-N-(pyridin-2-ylmethyl)aniline), was designed and synthesized to detect Cu2+ ions. BIPMA exhibited a fluorescent “turn-on” mechanism when bound to Cu2+ ions in an acetonitrile/water mixture (5:5, v/v, HEPES 10 mM, pH 7.4) owing to the synergistic effect of the chelation-enhanced fluorescence and internal charge-transfer mechanisms. Moreover, the BIPMA probe effectively detected nanomolar-range concentrations (0–400 nM) of Cu2+ ions in an aqueous system with a detection limit of 4.80 nM; this value is significantly lower than that set by the U.S. Environmental Protection Agency (≈20 μM). Additionally, BIPMA showed an ultrafast response to Cu2+ ions, with a maximum intensity achieved 25 s after adding Cu2+. Furthermore, BIPMA detected Cu2+ ions in solutions with a pH range of 5–11, without being influenced by pH, underscoring its applicability under various physiological conditions. Density functional theory studies revealed that internal charge transfer was responsible for emission. Finally, BIPMA effectively detected Cu2+ ions in real water samples and living cells.