Microwave-Assisted Synthesis of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) Complexes of Tridentate Schiff Base N-(2-hydroxyphenyl) 2-hydroxy-5-bromobenzaldimine: Characterization, DNA Interaction, Antioxidant, and In Vitro Antimicrobial Studies

Abstract

Five mononuclear complexes of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with the Schiff base N-(2-hydroxyphenyl) 2-hydroxy-5-bromobenzaldimine were synthesized under microwave irradiation. The microwave irradiation method was found remarkably successful and gave higher yield at a less reaction time. The complexes were fully characterized by elemental analyses, FT-IR, 1H NMR, EPR, FAB mass spectra, electronic spectra, molar conductivity, magnetic susceptibility measurements, and thermogravimetric analyses (TGA). Structural compositions were assigned by mass spectral studies. Four-coordinate geometry has been assigned to these complexes tentatively. The interaction of the complexes with calf thymus DNA (CT-DNA) was investigated by absorption spectroscopy, emission spectroscopy, and viscosity measurements. The experimental evidences indicated that the binding strength follow the order Cu(II) > Mn(II) > Co(II) > Ni(II) >Zn (II). Moreover, the complexes were examined for their antioxidant activities against reactive oxygen species (O2 · − and HO · radicals). Additionally, the ligand and its complexes were screened in vitro for their antibacterial and antifungal activities. Preliminary information obtained from the present work would help in the development of nucleic acid molecular probes and new therapeutic reagents for diseases.