Abstract
The Schiff base ligand 5-bromo-3-(((8-hydroxy-2-methylquinolin-7-yl)methylene)hydrazono)indolin-2-one (BHMQMHI) was prepared via condensation of 5-bromo-3-hydrazonoindolin-2-one and 7-formyl-8-hydroxy-2-methylquinoline and its Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) complexes have been synthesized and characterized by elemental analysis, conductance data, magnetic susceptibility measurements, IR, UV-Vis, mass spectrometry, 1H NMR, ESR, XRD, and thermal studies. By these spectral studies it is found that Co(II), Ni(II), and Cu(II) complexes have exhibited octahedral geometry whereas the Zn(II), Cd(II), and Hg(II) complexes have exhibited tetrahedral geometry. Potentiometric studies have been carried out on complexes of Schiff base (BHMQMHI) with Cu(II), Co(II), and Ni(II). Calvin-Bjerrum pH-titration technique as used by Irving and Rossotti has been applied to determine stability constants in mixed solvents at 25 ± 1°C. The present study reports the protonation constants of this ligand and stability constants of its metal complexes in dioxane-water (50%, v/v) mixtures. Metal-ligand stability constants fall in the order of Cu(II) > Co(II) > Ni(II) which is in agreement with those reported by Irving stability order. The Schiff base (BHMQMHI) and its metal complexes have been screened for their in vitro antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage activities of all the complexes were studied by agarose gel electrophoresis method. In addition, the free ligand along with its complexes has been studied for their antioxidant activity.
Highlights
Schiff base complexes have undergone a phenomenal growth during the recent years because of the versatility offered by these complexes in the field of industries, catalysis and biological system, and so forth
The in vitro biological screening effects of the investigated compounds were tested against the bacteria S. aureus, B. subtilis, and P. aeruginosa cultured on Mueller Hinton agar media
This study shows that synthesized Schiff base (BHMQMHI) acts as tridentate ligand coordinating to metal ion through azomethine nitrogen, carbonyl oxygen, and phenolic oxygen atom via deprotonation
Summary
Schiff base complexes have undergone a phenomenal growth during the recent years because of the versatility offered by these complexes in the field of industries, catalysis and biological system, and so forth In this way, the synthesis, structural investigation, and reaction of transition metal Schiff bases have received a special attention, because of their biological activities as antitumoral, antifungal, and antiviral activities [1]. Many researchers have synthesised these compounds as well as their metal complexes as target structures and evaluated their biological activities. These observations have guided the development of new hydrazones with varied biological activities. Biological studies of some transition metal complexes with the host of a bishydrazone derived from 5-bromo-3hydrazonoindolin-2-one and 7-formyl-8-hydroxy-2-methylquinoline, namely, (5-bromo-3-(((8-hydroxy-2-methylquinolin-7-yl)methylene)hydrazono)indolin-2-one (BHMQMHI))
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