Naked eye and fluorescent detections of Hg2+ ions and Cysteine via J-aggregation and deaggregation of a perylene bisimide derivative

• Selective naked eye and fluorescent sensor responses of a PBI derivative are reported for the first time towards Hg2+ ions and Cysteine (Cys) via J-aggregation and deaggregation mechanisms.
• The linear complex formation by PBI-Hg2+ ensemble was confirmed through FT-IR and 1H NMR spectral studies and well supported by its reversible nature upon the addition of PMDTA.
• The detection limits of Hg2+ ions and Cys were calculated as 36.6 and 91.3 nM, respectively, by standard deviation and linear fittings.

Selective naked eye and fluorescent sensor responses of a 1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) derivative are reported for the first time toward Hg2+ ions and Cysteine (Cys) via J-aggregation and deaggregation mechanisms. The J-aggregation and deaggregation of PBI induced by Hg2+ and Cys were well established by UV–vis/PL and 1H NMR titrations. The 1:1 stoichiometry of PBI-Hg2+ and Cys-Hg2+/PBI ensembles were elucidated from the jobs plots based on their UV–vis spectral changes. The linear complex formation by PBI-Hg2+ ensemble was confirmed through FT-IR and 1H NMR spectral studies and well supported by its reversible nature upon the addition of pentamethyl diethylene triamine (PMDTA). The positive cooperativities of Hg2+ and Cys (with PBI) in PBI-Hg2+ and Cys-Hg2+/PBI ensembles were evidenced from the Hill plots based on their fluorescence binding isotherms. The detection limits of Hg2+ ions and Cys were calculated as 36.6 and 91.3 nM, respectively, by standard deviations and linear fittings of their Stern–Volmer (KSV) constants and relative fluorescence intensity changes, respectively. Furthermore, the sensor properties of PBI were well investigated by KSV constants, pH values, time effects, and time resolved photoluminescence (TRPL) spectra.

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