A novel dual-function chemosensor for visual detection of Cu2+ in aqueous solution based on carbazole and its application

Abstract

A novel carbazole derivative, named as 3-(9-butyl-9H-carbazol-3-yl)-2-{4-[(4-di-ethylamino-2- hydroxy-benzylidene)-amino]-phenyl}-acrylonitrile (CPA), was obtained for the detection of Cu2+. CPA exhibited dual-function responses to Cu2+ over other competitive metal ions in CH3CN-Tris (20 mM, v/v = 1:1, pH = 7.2) solution. CPA could detect Cu2+ by UV–vis method, and the color changed from yellow-green to colorless, which could be readily distinguished by the naked eye. With the addition of various metal ions into the CPA solution, only Cu2+ caused the fluorescence of the CPA quenching. Other cations such as Na+, K+, Ca2+, Mg2+, Ni2+, Fe3+, Co2+, Cu2+, Zn2+, Hg2+, Ag+, Cd2+, Pb2+ and Al3+ could not induce similar response. The binding process was reasonably speculated by UV–Vis absorption and fluorescence measurements, 1H NMR titrations, mass spectroscopy (MS) and density functional theory (DFT) calculation. In addition, the coordination reaction was reversible and rapid. Strip papers were also devised and used to detect Cu2+ in aqueous solution, whose color change showed their potential application for on-site detection of Cu2+ in pollution water. And CPA could be visual in Hela cells with excellent cell permeability, viz, monitoring exogenous Cu2+ ions as well as realizing an “on–off” process.