Synthesis, structural characterization, and biological activity of a silver (I) thiosemicarbazides complex and new ligands of thiadiazole, triazole and oxadiazole derived from isonicotinoyl chloride

	Synthesis, structural characterization, and biological activity of a silver (I) thiosemicarbazides complex and new ligands of thiadiazole, triazole and oxadiazole derived from isonicotinoyl chloride
Journal of College of Education
Article 1, Volume 0, Issue 6, 2017, Pages 344-365
Abstract
In this work isonicotinoyl chloride (1) was prepared from isonicotinic acid & thionyl chloride, and then converted into the isonicotinoyl hydrazide (2) and isonicotinoyl thiosemicarbazide (3). Treatment of compound (2) with (HCl/NH4SCN) or (KOH/CS2) or phenyl isothiocyanate gave isonicotinoyl thiosemicarbazide (3), 2- thiol-5-(4-pyridyl)-1,3,4-oxadiazole (4) and 1-isonicotinoyl-4-phenyl thiosemicarbazide (5) which upon refluxing with (NaOH) yielded the corresponding 3-thiol-4-phenyl-5-(4-pyridyl)-1,2,4-triazole (6). Compound (4) thiol`s group is converted into hydroxyl group by treating with (H2O2/NaOC2H5) giving the compound 2-hydroxy- 5-(4- pyridyl)-1, 3, 4-oxadiazol (7). Reaction of isonicotinoyl thiosemicarbazide (3) with (NaOH) or cold conc. (H2SO4) leads to ring closure giving 2-thiol-5-(4-pyridyl)-1,3,4-triazol (8) and 2-amino- 5-(4-pyridyl)-1,3,4-thiadiazol (9). Complex (C3 and C5) were prepared from compounds (3 and 5) with silver nitrate. Compound and complex structures were characterized by IR, U.V spectra, and elemental analysis. Structural studies of complexes (C3 and C5) showed that the silver ion is four-coordinated with a square planar environment. Finally the biological activity of the synthesized compounds upon E.coli were evaluated. The ligands and complexes were found sensitive.
Keywords
thiadiazole; oxadiazole; Triazole; thiourea derivatives; Acid hydrazide; Thiosemicarbazide

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