Visual detection of Al3+ ions using conjugated copolymer-ATP supramolecular complex

• A novel water soluble polythiophene copolymer that demonstrates colorimetric response for Al3+ is proposed.
• Optimized ratio of two polythiophene monomers is utilized for selective detection of Al3+.
• Naked eye detection of Al3+ is demonstrated without involving sophisticated instrumentation.
• Lowest concentration of Al3+ for naked eye detection is ~4 μM, which is below the threshold levels.

A colorimetric Al3+ sensor based on fluorescence recovery of a conjugated copolymer-ATP complex is proposed. An optimized ratio of two polythiophene (PT) monomers is utilized to synthesize copolymer (CP) that yielded maximized colorimetric response for Al3+ in deionized (DI) and tap water. The electrostatic disassembly of CP-ATP upon addition of Al3+ led to an evident visual color change. The lowest concentration of Al3+ for naked eye observation is around 4 μM, which is below the threshold levels in drinking water according to European Economic Community (EEC) standard. Besides, the proposed assay showed a similar response to Al3+ in tap water. The proposed methodology showed selective and sensitive detection for Al3+ in analytically relevant concentration ranges without involving sophisticated instrumentation, illustrating the applicability for on-site drinking water monitoring.

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