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The selective and sensitive detection of biothiols; cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in aqueous solutions is of considerable importance because of their pivotal roles in maintaining the reducing environment in the cells. This study describes a strategy for the determination of biothiols based on the PDI/Met‐Hg2+complex platform. We designed and fabricated methionine modified perylene diimide molecule as a selective sensing probe for Hg2+ ions in aqueous solutions (PDI/Met‐Hg2+). The complex between perylene bisimide derivative (PDI/Met) and Hg2+ was investigated and it demonstrated turn‐on fluorescence response for the detection of the biological thiols. Besides, PDI/Met displayed fluorescence quenching response in the presence of mercury ions and the emission intensity of PDI/Met‐Hg2+ was recovered after transferring biothiols (Cys, Hcy, and GSH). Thus, PDI/Met could be utilized as a fluorescent chemosensor for the sequential recognition of mercury ions and biological thiols.

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A fluorogenic probe based on a coumarin-derivative for Cu 2+ sensing in CH 3 CN/H 2 O media (v/v, 95/5, 5.0 µM) was developed and applied in real samples. 3-(4-chlorophenyl)-6,7-dihydroxy-coumarin (MCPC) probe was obtained by synthetic methodologies and identified by spectral techniques. The probe MCPC showed remarkable changes with a "turn-off" fluorogenic sensing approach for the monitoring of Cu 2+ at 456 nm under an excitation wavelength of 366 nm. The response time of the probe MCPC was founded as only 1 min. The detection limit of the probe MCPC was recorded to be 1.47 nM. The binding constant and possible stoichiometric ratio (1:1) values were determined by Benesi-Hildebrand and Job's plot systems, respectively. The mechanism of the probe MCPC with Cu 2+ was further confirmed by ESI-MS and FT-IR analyses, as well as supported by theoretical calculations. Furthermore, the probe MCPC was successfully employed for the practical applications to sense Cu 2+ in different herbal and black tea samples. The proposed sensing method was also verified by ICP-OES method.

A propylimidazole functionalized coumarin derivative (IPC) was fabricated for the rst time and applied as a dual responsive uorescent chemoprobe for sensitive and selective recognitions of picric acid (PA) and Fe 3+ . Strong uorescence quenching phenomena of the IPC were observed in H 2 O/ACN (5/95, v/v) medium (λ em =408 nm) upon the additions of Fe 3+ or PA. The fabricated dual responsive IPC offered good selectivity and sensitivity with the low limit of detection values (0.92 µM for PA and 0.22 µM for Fe 3+ ) lower than the acceptable amounts of Fe 3+ and PA by the international o cial authorities. The interaction phenomena of IPC with PA and Fe 3+ based on the ndings of a range of experiments were considered and DFT computations were done to verify their recognition mechanisms. The sensing phenomena of IPC towards PA (1:1) and Fe 3+ (3:1) were con rmed by the MALDI TOF-MS, FT-IR, 1 H-NMR titration and Job's methods. Furthermore, the compound IPC was effectively applied as a uorescent sensor for Fe 3+ and PA detection in real natural spring water samples.