Studies on metal complexes of 2-((8-hydroxyquinolin-5-yl)methylene)benzobthiophen-3(2H)-one 1,1-dioxide

摘要

The novel Schiff base 2-((8-hydroxyquinolin-5-yl)methylene)benzob thiophen-3(2H)-one 1,1-dioxide (3) was synthesized by Remier-Tieman reaction of benzob thiophen-3(2H)-one 1,1-dioxide (1) with 8-hydroxyquinoline-5-carbaldehyde (2). Metal complexes (4a-f) of the Schiff base (3) were prepared from salts of a variety of transition metal ions, viz., Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II). The Schiff base and its metal complexes were characterized by physicochemical, thermogravimetric, and spectroscopic analysis. Thermogravimetric analysis revealed the number of water molecules in the metal complexes. Electronic spectral analysis and magnetic measurement studies were used to determine the geometry of the complexes. The compounds were evaluated for antibacterial activity against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Salmonella typhimurium and Escherichia coli) bacteria. Growth inhibition was compared with that by the standard drug ciprofloxacin. Antifungal activity was tested against four fungi (Penicillium expansum, Botryodiplodia theobromae, Nigrospora sp., and Trichothesium sp.), with the antifungal drug ketoconazole as positive control.