Synthesis of NNNN Tetradentate Macrocyclic Ligand and its Pd(II), Pt(II), Ru(III), and Ir(III) Complexes: Spectroscopic, Thermal, and Antimicrobial Studies

Pd(II), Pt(II), Ru(III), and Ir(III) complexes of general stoichiometry [PdL]Cl2, [PtL]Cl2, [Ru(L)Cl2]Cl, and [Ir(L)Cl2]Cl, with tetradentate macrocyclic ligand, derived from 2,6-diaminopyridine with 3-methyl 2,4-pentanedione has been synthesized. The ligand was characterized on the basis of elemental analyses, IR, mass, and 1H NMR and 13C NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, mass, electronic spectral techniques, and thermal studies. The value of magnetic moments indicates that all the complexes are diamagnetic except Ru(III) complex, which shows magnetic moments corresponding its one unpaired electron. The macrocyclic ligand and all its metal complexes were tested in vitro against some plant pathogenic fungi and bacteria to assess their biocidal properties.