Performance of Ortho, Meta and Para Bearing Benzoylthiourea Derivatives with Nitro Derivative with Nitro Substitutuent as Chemosensor for Detection of Metal Ions

Chong, Wai Ting (2023) Performance of Ortho, Meta and Para Bearing Benzoylthiourea Derivatives with Nitro Derivative with Nitro Substitutuent as Chemosensor for Detection of Metal Ions. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Ligands of o-, m- and p-nitrobenzoyl thiourea with an electron-withdrawing group (NO2) have been synthesized and characterized in the basic of FTIR, UV-Vis spectroscopy, CHNS elemental analysis and 1H and 13C NMR. The 2,3,4-nitrobenzoyl thiourea ligands were designed to apply as colourimetric chemosensors to detect Cu2+. Fourier Infrared FTIR results for the functional groups of C=O, N=H, C=S and N-O were consistent with the theoretical result calculated from DFT. UV-Vis spectra of L1, L2 and L3 were found to be similar to TD-DFT theoretical result as two intense peaks corresponding to to π → π* and n → π* transitions, which correspond to a benzene ring and C=O and C=S, respectively, with referred of the frontier molecular diagram. Elemental analysis for L1, L2 and L3 was compatible with the expected theoretical calculation. Both 1H and 13C NMR results were well agreed with the structure of the synthesized ligands. For the application, all three ligands were highly selective to Cu2+ in ACN/ H2O solution, with the MLCT band appearing at the wavelength of 452nm,452nm and 462nm for L1, L2 and L3, respectively. The colour changed from colourless to yellow after adding Cu2+, while other metal ions remained colourless after adding. The recognition mechanism was analyzed by FTIR, the shifting of stretching frequency of the N-H group, which indicates the binding process of L- Cu2+ occurs through the N-H group. The stoichiometry was measured by Job’s plot method, which indicates the L- Cu2+ bound in a 2:1 ratio. The detection limit of the L1 towards Cu2+ was 5×10-5 M, which is more sensitive to Cu2+when compared to L2 and L3 with a detection limit of 1×10-4 M.