Performance of the Ortho, Meta and Para Electron-Donating Bearing Symmetrical Benzoylthuourea Act as Chemosensor for Heavy Metal Ion Detection

Chong, See Yen (2023) Performance of the Ortho, Meta and Para Electron-Donating Bearing Symmetrical Benzoylthuourea Act as Chemosensor for Heavy Metal Ion Detection. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

Text Chong See Yen_Full Text.pdf Restricted to Registered users only Download (3MB)

Abstract

The highly selective and sensitive colorimetric chemosensors which are o-methoxybenzoylthiourea (L1), m-methoxybenzoylthiourea (L2) and p-methoxybenzoylthiourea (L2) for detection of Cu2+ ions with a fast response time have been synthesized and characterized through melting point apparatus, DSC, CHNS elemental analyses, FTIR, UV-Vis, 1H and 13C NMR. The spectroscopic properties of both L1, L2, and L3 were investigated based on experimental and computation studies. The optimized geometry, energy levels of frontier molecular orbital, theoretical vibrational, and absorption spectra were well calculated through DFT and TD-DFT methods by using Gaussian 09 software. Both experimental and theoretical results are consistent. The sensors synthesized are highly selective towards the Cu2+ ion in ACN/H2O binary solution with a fast response time as the colour change of the solution from colourless to yellow colour can be observed immediately after the mixture of the ligand solutions and copper (II) ion solutions, while the cations Fe2+, Fe3+, Co2+, Mn2+, and Hg2+ did not change the colour of ligand solutions. In addition, the signal has been determined by using the UV-Vis spectrophotometer. In the UV-Vis spectra, both sensors displayed the MLCT absorption band at a similar wavelength, 462 nm for the mixture of ligands and Cu2+, while the mixture of ligands with other metal ions did not have the absorption band in the visible region. Then, the detection limit of sensors towards Cu2+ was studied by using UV-Vis spectrophotometric titration and both of the sensors had a similar detection limit, which is 5.0 × 10-5 M. Apart from that, the possible binding mode of the sensors with Cu2+ ion was studied by using Job’s method and FTIR spectroscopy. The proposed mechanism was two sensors bound with one Cu2+ ion via the N-H bond at which the stoichiometry of sensors and Cu2+ was in the ratio of 2:1. The test strips based on sensors were fabricated to use as a convenient and efficient Cu2+ ion detection kit.