Synthesis of Redox-Active, Fluorescent Triphenylamine Derivative for Detection of Heavy Metal Ions

A triphenylamine derivative 4',4''-dinitro-4'''-phenethoxytriphenylamine (2) was successfully obtained via cesium fluoride assisted nucleophilic arylation. The structure of the 2 compound was characterized by FTIR, H-1-NMR, and C-13-NMR spectroscopic analyses. The absorption and emission spectral profiles, recorded on UV-visible and photo-luminescence (PL) spectrometer, indicated the emission of light in the yellow region at lambda(emis) = 570 nm. The solution (10 mu M) of the synthesized compound in DMSO titrated against aqueous solutions of Pb2+, Cu2+, Fe2+, and Ni2+ to determine the ligand-metal interaction, indicated excellent interaction with the aforementioned heavy metal ions in aqueous media. Furthermore, the adsorption characteristics of the solid-state 2 were explored by screening various heavy metal ions. The atomic absorption spectrometry was used to estimate the amount of heavy metal ions adsorbed on the surface of the adsorbent. The Langmuir and Freundlich isotherm models were used to further explore the adsorption behavior of the synthesized adsorbent 2. The Langmuir isotherm model is the best fit for the Ni2+ ions, whereas Cu2+, Pb2+, and Fe2+ data fitted well to Freundlich isotherm model with regression constant (R-2) values in the range 0.991-0.997, indicating their appreciable association/adsorption on the synthesized compound. The synthesized fluorescent adsorbent could be used as a metal probe in the future.

Automated summary

The synthesized fluorescent adsorbent exhibited excellent interaction with heavy metal ions in aqueous media and showed significant adsorption of heavy metal ions in solid-state. The use of Langmuir and Freundlich isotherm models further explored the adsorption behavior of the adsorbent, indicating potential application as a metal probe in the future.