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Title:	Synthesis, characterization and antibacterial study of late first row transition metal complexes of 4n-substituted 6-(3-thienyl)pyridine-2-carboxaldehyde-3-thiosemicarbazone
Authors:	Omima Abdalla Mahjoub Abdalla (P57917)
Supervisor:	Yang Farina Abdul Aziz, Prof. Dr.
Keywords:	Antibacterial agents Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	29-Jun-2018
Description:	Thiosemicarbazone derivatives, a class of Schiff base compounds, have been extensively studied because they are easily synthesised by modifying their parent compound. The resultant Schiff bases would depend on the aldehyde or ketone used or by the substituent at the C5 or N1 atoms. Thiosemicarbazones are also studied for their versatile donor ability, structural diversity, analytical and biological applications. Four thiosemicarbazone ligands have been prepared with good yields by reacting 6-(3-thienyl)pyridine-2-carboxaldehyde with N1-thiosemicarbazide or N1-(substituted)-thiosemicarbazide in ethanol to give 6-(3-thienyl)pyridine-2-carboxaldehyde-3-thiosemicarbazone (Htpytsc), a, 6-(3-thienyl)pyridine-2-carboxaldehyde-4-methyl-3-thiosemicarbazone (Htpymtsc), b, 6-(3-thienyl)pyridine-2-carboxaldehyde-4-ethyl-3-thiosemicarbazone (Htpyetsc), c and 6-(3-thienyl)pyridine-2-carboxaldehyde-4-phenylthiosemicarbazone (Htpyptsc), d. The reaction of nitrate/chloride salts of Ni(II), Cu(II), Co(II), Zn(II) and Ag(I) with ligand a-d formed 29 complexes. All ligands and metal complexes were characterized by elemental analysis (C, H, N, and S), spectroscopic methods (FT-IR, 1H, 13C and 31P NMR, UV-VIS) and X-ray crystallography. The magnetic susceptibility and molar conductivity of the complexes were measured. Spectroscopic data and x-ray crystal structure showed that the free ligands existed in the thione form and behave differently with metal ions. The ligands behave as a tridentate ligand coordinated via the pyridine nitrogen atom, the azomethine nitrogen atom and the sulphur atom for all metal ions except for Ag+, in which ligand a coordinated as a monodentate through the sulphur. The Ni(II) complexes (1a, 2a, 3a and 2c) are octahedral with two thiosemicarbazone ligands coordinating as neutral ligand however, in nickel(II) complex 3c the ligand coordinated as an anionic. Ni(II) complexes of ligand d and the cobalt(II) complexes (7a, 6d and 7d) are octahedral with two thiosemicarbazone ligands, one is neutral and the other is uninegative. However, complexes of 6a, 6b and 6c were found to be diamagnetic which confirms the oxidation of Co(II) to Co(III) with an octahedral geometry around Co(III) with two anionic thiosemicarbazone ligands. The zinc(II) complexes were found to be six and five coordinates. Zinc(II) complexes 9a, 8b, and 8c, showed the thiosemicarbazones in the thione form, while complexes 8a, 8d and 9d the thiosemicarbazone behaved as a thiol. The ligands c and d were coordinated with Cu(II) ions in either thione form or thiol form. While, ligands a and b were coordinated with Cu(II) ions only in the thione form. The Cu(II) complexes were mononuclear with pentagonal geometry around the Cu(II). Ag(I) formed only two mononuclear complexes with ligand a, in which a behaved as a neutral monodentate ligand. The in vitro antibacterial tests showed that the complexes have more antibacterial activity compared to the free ligands. Cobalt (III/II) complexes (6c), (6d), (7d) and the silver(I) complex (11a) were more active than the standard vancomycin against G(+) MRSA with an inhibition zone of 17, 15, 14 and 16 mm, respectively. The cobalt (III) complex 6c showed more activity than the standard chloramphenicol against G (+) B. subtilis and showed the same activity as gentamicin against G (+) S. aureus with an inhibition zone of 21 and 24 mm, respectively. Moreover, zinc(II) complex 8c showed the same activity as vancomycin against G (+) MRSA with an inhibition zone of 13 mm and copper(II) complexes 5a, 4c and 5c exhibited strong activity against G(+) MRSA with an inhibition zone of 12, 11and 12 mm, respectively.,'Certification of Master's/Doctoral Thesis' is not available,Ph.D.
Pages:	292
Call Number:	RM409.A233 2018 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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