A multifunctional quinoxaline-based chemosensor for colorimetric detection of Fe3+ and highly selective fluorescence turn-off response of Cu+2 and their practical application

Abstract

A new dual responsive colorimetric and fluorescent turn-off sensor for Fe3+ and Cu2+ was designed and synthesized based on quinoxaline derivative by a simple procedure reaction. 2,3-bis(6-bromopyridin-2-yl)-6-methoxyquinoxaline (BMQ) was fabricated and characterized using ATR-IR, 13C and 1H NMR, and Mass spectroscopy. The interaction of BMQ with Fe3+ caused a significant color change from colorless to yellow. The sensing complex BMQ-Fe3+ with high selectivity was described to be 1:1 by the molar ratio plot. In this experiment, iron was detected by naked-eye using a recently synthesized ligand (BMQ). This color change was unexpectedly observed in iron-overloaded plasma, which had previously been admitted by AAS (Atomic Absorption Spectroscopy). Normal plasma, however, did not exhibit this color change. Interestingly, Cu2+ ions cause a quench at the local emission around 565 nm. On the other hand, receptor-binding selectivity for Cu2+ over a wide linear concentration range was observed through changes in the emission spectra. BMQ-Cu2+ was characterized to be 1:1 by the Job's plot. The emission intensity of BMQ–Cu2+ complex was balanced within only 1 min. various mineral water samples were analyzed for detecting Cu2+. The results show the great potential of the developed probe BMQ for the sensing of Cu2+ ions in mineral and drinking water samples.