Abstract
An aminothiazole-based chromogenic chemosensor, (4-methyl-2-(phenylamino)thiazol-5-yl)(phenyl)methanone (MPTP), was synthesized via an iodine-catalyzed one-pot reaction and tailored for the selective and sensitive detection of Fe3+ ions. The sensor exhibited a distinct chromogenic transition from pale yellow to brown upon Fe3+ binding in ethanol. MPTP demonstrated pronounced positive solvatochromism, Job’s plot analysis confirms a 1:1 binding stoichiometry between MPTP and Fe3+, while Benesi-Hildebrand method reveals a high binding constant, indicative of strong complex formation, a low detection limit (LOD = 0.268 µM), and broad pH stability (2–12), with optimal performance in the physiologically relevant range of pH 6–10. The Fe3+-induced response was reversible through EDTA-mediated chelation, enabling facile sensor regeneration. A portable paper-based test strip incorporating MPTP reproduced the solution-phase chromogenic response, allowing rapid and visual detection of Fe3+ without instrumentation. Environmental and pharmaceutical Fe3+ analysis using simulated water and ferric citrate tablets confirmed the sensor’s applicability, achieving a 98% and 102% recovery rate. DFT calculations support the experimental data, attributing the 361 nm band to a π-π* transition with pronounced intramolecular charge transfer, and HOMO-LUMO/MEP analysis highlights nitrogen-rich sites as preferred Fe3+ binding centres, further underscoring MPTP as a robust probe for Fe3+ detection.
Data availability
The datasets used and analysed during the current study are available from the corresponding author on reasonable request.
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Acknowledgements
The authors, NS and CSK, thankfully acknowledge JSS Science and Technology University, Mysuru, for their funding support. One of the authors, KK, thanks Khalifa University of Science and Technology for their financial support.
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Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates, has supported this work.
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G.S. Rakshitha: synthesis, Formal analysis, and Writing - original draft. S Nanjundaswamy: Conceptualization, Supervision, Writing - review and editing. C.S. Karthik, K. Karuppasamy, P. Mallu, and Prof. Akram: Supervision, Writing - review and editing.
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Rakshitha, G.S., Karthik, C.S., Karuppasamy, K. et al. A robust aminothiazole-based colorimetric sensor for visual detection of Fe3+ ions in environmental and pharmaceutical samples. Sci Rep (2026). https://doi.org/10.1038/s41598-026-38683-5
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DOI: https://doi.org/10.1038/s41598-026-38683-5
