Abstract
In this paper, a Schiff base ligand 1-(2-thiophenylimino)-4-(N-dimethyl)benzene (SL1) bearing azomethine (>C=N-) and thiol (-SH) moieties capable of coordinating to metals and forming colored metal complexes was synthesized and examined as a colorimetric chemosensor. The sensing ability toward the metal ions of Cu2+, Cr3+, Fe2+ Ni2+, Co2+, Mg2+, Zn2+, Fe2+, Fe3+, NH4VO3 (V5+), Mn2+, Hg2+, Pb2+, and Al3+ was investigated in a mixture of H2O and dimethylformamide (DMF) solvent using the UV–Visible spectra monitoring method. The synthesized Schiff base ligand showed colorimetric properties with Cr3+, Fe2+, Fe3+, and Hg2+ ions, resulting in a different color change for each metal that could be identified easily with the naked eye. The UV–Vis spectra indicated a significant red shift (~69–288 nm) from the origin after the addition of the ligand to these metal ions, which may be due to ligand-to-metal charge-transfer (LMCT). On applying Job’s plot, it was indicated that the ligand binds to the metal ions in a 2:1 ligand-to-metal molar ratio. SL1 behaves as a bidentate ligand and binds through the N atom of the imine group and the S atom of the thiol group. The results indicate that the SL1 ligand is an appropriate coordination entity and can be developed for use as a chemosensor for the detection of Cr3+, Fe2+, Fe3+, and Hg2+ ions.
Highlights
The detection of transition metal ions as pollutants has gained extreme importance in chemical, biological, and environmental sciences because of the toxic impact of such ions on the environment and human health
Numerous analytical techniques have been employed for the determination of toxic transition metal elements including atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry, inductively coupled plasma (ICP), atomic emission spectrometry, and fluorescence spectroscopy
During the past few years, several chemosensors have evolved for the selective qualitative analysis of different metal ions based on metal–ligand coordination as the host–guest interaction principle [7,24]
Summary
The detection of transition metal ions as pollutants has gained extreme importance in chemical, biological, and environmental sciences because of the toxic impact of such ions on the environment and human health. Numerous analytical techniques have been employed for the determination of toxic transition metal elements including atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry, inductively coupled plasma (ICP), atomic emission spectrometry, and fluorescence spectroscopy. These techniques are very expensive to purchase and maintain, and the analysis cost per sample is typically high. They need a complicated procedure for ion analysis, which makes them inconvenient for routine analysis [1,2]. Recent analytical interest has focused on exploring different organic molecules with optical properties and employing them as chemosensors for the determination of metal ions [3,4,5,6]
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