Synthesis, Spectral and Theoretical Characterization and Antimicrobial and Cytotoxic Studies of Some Transition Metal Complexes of 4-[(2E)-2-Benzylidenehydrazinyl]-7H-pyrrolo[2,3-d]pyrimidine

Abstract

Present work describes the synthesis and characterization of complexes of 4-[(2E)-2-benzylidenehydrazinyl]-7H-pyrrolo[2,3-d]pyrimidine with Fe(II), Mn(II), Co(II), Ni(II), Pd(II), Zn(II), Cu(II), Cd(II) and Hg(II). The results of the elemental and spectroscopic analyses suggest a 1:2 metal-ligand ratio, [ML2]. The electronic spectra and magnetic moments of the metal(II) complexes suggest that Fe(II), Mn(II), Co(II) and Ni(II) complexes are in an octahedral geometry, while Pd(II) in a square planar ligand geometry. In contrast, the Cu(II), Zn(II), Cd(II) and Hg(II) are in tetrahedral geometry. The conductance measurements in nitrobenzene suggest the non-electrolytic nature of all the metal-coordination compounds. The tested biological species viz. Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Proteus mirabilis, Klebsiella oxytoca, Aspergillus niger, A. flavus and Rhizopus stolonifer exhibited the moderate to strong antimicrobial activity. At 10 mg/mL concentration in nitrobenzene, cobalt(II) complex is observed to be a more promising antimicrobial than any other metal(II) complexes synthesized. The antioxidant potential of the synthesized metal(II) compounds was also evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and shows the high DPPH radical scavenging activity. The nickel complex had the highest DPPH radical scavenging activity compared to the other metal(II) complexes.