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Copper being an essential nutrient; also pose a risk for human health in excessive amount. A simple and convenient method for the detection of trace amount of copper was employed using an optical probe R1 based on Schiff base. The probe was synthesized by Schiff base condensation of benzyl amine and 2-hydroxy-1-napthaldehyde and characterized by single X-ray diffraction, 1 H NMR and FTIR. By screening its fluorescence response in a mixture of DMSO and H 2 O (20:80, v/v) R1 displayed a pronounced enhancement in fluorescence only upon treatment with copper. Other examined metal ions such as alkali, alkaline and transition had no influence. Within a wide pH range 5-12 R1 could selectively detect copper by interrupting ICT mechanism that results in CHEF. From Job's plot analysis a 2:1 binding stoichiometry was revealed. The fluorescence response was linear in the range 1-10 × 10 -9  M with detection limit 30 × 10 -9  M. Association constant was determined as 1 × 10 11  M -2 by Benesi-Hilderbrand plot. As a fast responsive probe it possesses good reproducibility and was employed for detection of copper in different water samples.

• A simple Schiff base sensor (RN2) was synthesized and applied for Cu2+ detection in aqueous media. • Upon interaction with Cu2+ the colour of solution was changed from yellow to pale yellow. • Fluorescence of RN2 was enhanced upon the gradual addition of different concentration of the Cu2+. • RN2 could selectively and sensitively detect Cu2+ with a low detection limit (5.6 nM). • RN2 was successfully applied for Cu2+ detection in the water samples and blood serum. Herein, Sensor RN2 was prepared by condensation of 2‑hydroxy-1-naphthaldehyde and 2-chloroaniline and well characterized by FTIR, PXRD, 1H NMR, and 13C NMR. Photophysical investigation reveals that sensor RN2 exhibits remarkable colorimetric and fluorometric "turn-on" behavior towards Cu2+ with high selectivity and sensitivity in the presence of other examined metal ions. The stoichiometric ratio was determined to be 2:1 for RN2 and Cu2+ based on the Job plot, DFT and HRMS analysis. The detection limit for Cu2+ reached the nM level. The binding constant of RN2 with Cu2+ was 2.55 × 1011 M −2. RN2 was successfully applied for quantitative recognition of Cu2+ in biological and environmental samples. The test strips based on RN2 were fabricated, which could act as an efficient and convenient Cu2+test kit. [Display omitted] [ABSTRACT FROM AUTHOR]

Copper being an essential nutrient; also pose a risk for human health in excessive amount. A simple and convenient method for the detection of trace amount of copper was employed using an optical probe R1 based on Schiff base. The probe was synthesized by Schiff base condensation of benzyl amine and 2-hydroxy-1-napthaldehyde and characterized by single X-ray diffraction, 1H NMR and FTIR. By screening its fluorescence response in a mixture of DMSO and H2O (20:80, v/v) R1 displayed a pronounced enhancement in fluorescence only upon treatment with copper. Other examined metal ions such as alkali, alkaline and transition had no influence. Within a wide pH range 5-12 R1 could selectively detect copper by interrupting ICT mechanism that results in CHEF. From Job’s plot analysis a 2:1 binding stoichiometry was revealed. The fluorescence response was linear in the range 1-10 × 10−9 M with detection limit 30 × 10−9 M. Association constant was determined as 1 × 1011 M−2 by Benesi-Hilderbrand plot. As a fast responsive probe it possesses good reproducibility and was employed for detection of copper in different water samples. [ABSTRACT FROM AUTHOR]