New Chromenylium-cyanine based dual channel chemosensors for copper and hypochlorite sensing

Abstract

Based on a change in optical properties of chromenylium-cyanine Schiff base derivatives (5a-c), a series of colorimetric dual sensors have been for the first time designed, synthesized and characterized to monitor Cu2+ and OCl- ions at near-IR (NIR) region in aqueous samples. the colorimetric responses of the sensors toward Cu2+ and OCI- ions were evaluated for aqueous samples within a series of the competitive anions and cations at pH 7.2. the sensors detected Cu2+ selectively via Cu2+-promoted spimcyclic ring-opening reaction while photophysical change during OCl- recognition is due to the spimcyclic ring-opening reaction by coordination Cu2+ ion generated from reaction between Cu+ and hypochlorite ions in analysis media. Mass and IR data suggest a 1:1 complex formation between Cu2+ and the receptor via phenolic O atom, N atom from Schiff base and O atom from spirocycle form. the detection limits of the dual sensors (5a-c) were determined to be 3.3 x 10(-8) M, 1.93 x 10(-8) M and 2.36 x 10(-8) for Cu2+ determination and 2.83 x 10(-8) M, 2.10 x 10(-8) M and 2.60 x 10(-8) M for OCl- determination, indicating a high sensitivity of the sensors for Cu2+ and OCl- detection Additionally, we present the first single-crystal structure analysis of a chromenylium-cyanine Schiff base in this study.