Simple pyridyl-salicylimine-based fluorescence “turn-on” sensors for distinct detections of Zn2+, Al3+ and OH− ions in mixed aqueous media

Abstract

Simple pyridyl-salicylimine derivatives (F1, F2 and F3) are reported for the first time as fluorescence "turn-on" sensors for distinct detections of Zn(2+), Al(3+) and OH(-) ions in mixed-aqueous media CH3CN/H2O with volume ratios of 6/4 and 3/7 (at pH = 7 and 25 °C) via internal charge transfer (ICT), chelation enhanced fluorescence (CHEF), and deprotonation mechanisms. F1 and F2 show diverse turn-on sensing applications to Zn(2+), Al(3+) and OH(-) ions, but F3 exhibited the fluorescence turn-on sensing to Al(3+) and OH(-) ions in CH3CN/H2O (6/4; vol/vol). F1+Zn(2+) and F2+Zn(2+) complexes revealed the reversibilities and ratiometric displacements of Zn(2+) with ethylene diamine tetra acetic acid (EDTA) and Al(3+) ions, respectively, in CH3CN/H2O (6/4; vol/vol). On the other hand, F1, F2 and F3 in CH3CN/H2O (3/7; vol/vol) showed sensitivities only to Al(3+) ions but negligible selectivities to OH(-) ions. Stoichiometry of all sensor complexes were calculated as 1 : 1 by job's plots based on UV/Vis and PL titrations. The complex formation and binding sites of all sensor materials were well characterized by (1)H, (13)C NMR, and mass (FAB) spectral analysis. Detection limits were calculated from standard deviations and linear fitting calculations. The association constant (log K(a)) values of sensor complexes were evaluated from the fluorescence binding isotherms. The fluorescence decay constant (τ) values were estimated from time resolved fluorescence studies. Time, temperature, pH and solvent concentration effects towards sensor responses were fully investigated in this report.

A turn-on fluorescence chemosensor for Al3+, F− and CN− ions, and its application in cell imaging

“…[57] The detection limit is comparable to the reported (10 -6 mol·L -1 ). [58,59] These results demonstrated that HL is highly selective and sensitive for Al 3+ ion.…”

A new bifunctional Schiff base as a colorimetric and fluorescence sensor for Al3+ and CN−

“…S6). The observed fluorescent enhancement may be attributed to the formation of a rigid system after binding with Al 3+ , causing the chelation-enhanced fluorescence (CHEF) effect [28][29][30]. This unique selectivity of receptor 2 toward Al 3+ could be interpreted in terms of the smaller ionic radii and higher charge density of the Al 3+ ion.…”

A Simple and Highly Sensitive Turn-on Schiff Base Type Naked-eye Fluorescent Sensor for Aluminum Ion in Living Cells

“…7 Therefore, it is important topic to design and develop effective analytical methods or instruments for detection of aluminum ions in environmental and/or biological systems. Although many different and sophisticated analytical techniques including inductively coupled plasma emission (ICP-OES) or mass spectrome-try (ICP-MS), and atomic absorption spectrometry have been used extensively for the detection of aluminum ions, 8,9 most of these techniques have some disadvantages such as time consuming, qualified personal and high cost. 10 But among them, fluorescence spectroscopy is most popular analytical instrument for the detection of metal ions and it is preferred intensively by scientists in analytical applications owing to its easy operation, comparatively low cost, and high sensitivity, etc.…”