A new phthalocyanine probe with superior analytical performance for visual and fluorometric detection of thiosulfate in real samples

In this study, a two-channel, ratiometric, colorimetric, and near-infrared phthalocyanine-based probe (Q-DMAPZnPc) was synthesized and applied for the first time for highly selective/sensitive determination of toxic S₂O₃²⁻ in real samples through significant spectral changes. After the addition of S₂O₃²⁻ to the solution of Q-DMAPZnPc, the color of the solution changed from turquoise to lime green, facilitating on-site analysis through visual detection. Q-DMAPZnPc has superior analytical performance for the determination of S₂O₃²⁻ compared to related studies in the literature; the fastest response time (30 s for both UV–vis and fluorescence), very low limits of detection (1.45 µM and 0.15 µM for UV–vis and fluorescence), long term durability (more than 3 months), and dual-channel sensing. A smartphone application was successfully applied for colorimetric analysis of S₂O₃²⁻ within the range of 7.50 μM and 32.43 μM. Binding behavior and the optoelectronic properties of the Q-DMAPZnPc-S₂O₃²⁻ complex were enlightened with DFT calculations.