Spectral characterization and antibacterial, antifungal, antiviral activity of salicyl based new Schiff bases and their Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) complexes

Two new salicyl based Schiff bases derived from 3,5-dichlorosalicylaldehyde and 4-(chloro/tert-butyl)-2-aminophenols (H2L1 and H2L2) and their complexes with cobalt(II), nickel(II), copper(II), zinc(II), and palladium(II), {[M(Ln)(H2O)]∙xH2O, M(II) = Co(II) (n = 1, 2; x = 1), Ni(II) (n = 1, x = 2; n = 2, x = 0), Cu(II) (n = 1, 2; x = 0), Zn(II) (n = 1, 2; x = 0); K[Pd(Ln)Cl]; n = 1, 2}, were synthesized and characterized. The structural characteristics of the complexes were examined by means of elemental analysis, molar conductivity, magnetic moment, thermogravimetric analysis (TGA), UV-visible, FT-IR, and NMR spectroscopy. In addition, the crystal structures of H2L1 and H2L2 were determined by X-ray single diffraction measurements. All the complexes are non-electrolyte with 1:1 M:L ratio. Antibacterial and antifungal activity of the compounds was evaluated against six bacteria and three fungi. In general, all the compounds showed moderate antimicrobial activity. Some of the complexes exhibited higher activity towards some microorganisms than the ligands. Antiviral activity of the compounds was tested against Parainfluenza Type-2 virus. The fact that H2L2 has a higher antiviral effect than H2L1 can be evaluated as that the tert-butyl group promotes the antiviral effect.