Abstract
The Schiff base hydrazone ligand HL was prepared by the condensation reaction of 7-chloro-4-quinoline with o-hydroxyacetophenone. The ligand behaves either as monobasic bidentate or dibasic tridentate and contain ONN coordination sites. This was accounted for be the presence in the ligand of a phenolic azomethine and imine groups. It reacts with Cu(II), Ni(II), Co(II), Mn(II), UO2 (VI) and Fe(II) to form either mono- or binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, NMR, Mass, and UV-Visible spectra. The magnetic moments and electrical conductance of the complexes were also determined. The Co(II), Ni(II) and UO2 (VI) complexes are mononuclear and coordinated to NO sites of two ligand molecules. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, the Ni(II) complex is octahedral while the UO2 (VI) complex has its favoured heptacoordination. The Co(II), Mn(II) complexes and also other Ni(II) and Fe(III) complexes, which were obtained in the presence of Li(OH) as deprotonating agent, are binuclear and coordinated via the NNNO sites of two ligand molecules. All the binuclear complexes have octahedral geometries and their magnetic moments are quite low compared to the calculated value for two metal ions complexes and thus antiferromagnetic interactions between the two adjacent metal ions. The ligand HL and metal complexes were tested against a strain of Gram +ve bacteria (Staphylococcus aureus), Gram −ve bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited high antibacterial activities.
Highlights
Schiff bases play an important role in inorganic chemistry as they form stable complexes with most transition metal ions
In the present investigation we describe the synthesis, characterization, and antimicrobial activity of transition metal complexes of a novel Schiff’s base hydrazone containing the quinoline moiety; o-hydroxyacetophenone-7-chloro-4-quinoline hydrazine (HL)
Organic solvents used were reagent grade. 4,7-Dichloroquinoline was obtained as a commercial sample from EI-NasrCompany for Pharmaceutical Chemicals (Cairo, Egypt), and was purified in the laboratory as follows: Under warming and constant stirring, 10 g (10 mmol) of the sample were dissolved in absolute ethanol
Summary
Schiff bases play an important role in inorganic chemistry as they form stable complexes with most transition metal ions. Hydrazones derived from condensation of isonicotinic acid hydrazide with pyridine aldehydes have been found to show better antitubercular activity than. Agarwa investigated the coordinating ability of INH-derivatives with metal ions [13]. Tri- and terdentate Schiff bases may contain ONO or ONS donor atoms. Their metal complexes may be monomeric, dimeric, trimeric or tetrameric with abnormal magnetic properties and characteristic structures [14,15,16]. In the present investigation we describe the synthesis, characterization, and antimicrobial activity of transition metal complexes of a novel Schiff’s base hydrazone containing the quinoline moiety; o-hydroxyacetophenone-7-chloro-4-quinoline hydrazine (HL)
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