Synthesis and characterization of chiral mixed ligand Co(II) complexes of isonitrosopropiophenone and amino acids

Chiral mixed-ligand (CML) metal complexes of the type M(INPP)L'.H2O where M is Co(II), HINPP = isonitrosopropiophenone, and HL' = chiral amino acid, such as L-alanine, L-phenylalanine, L-leucine, L-methionine and L-valine, have been synthesized. The same CML Co(II) complexes could also be synthesized from racemic amino acids using Co(II) : HINPP : racemic amino acids in 1 : 1 : 2 proportion by in situ stereoselective complexation. The complexes have been characterised by various physico-chemical techniques. The electrical conductance studies of the complexes in nitrobenzene solution at 10(-3) M concentration indicate their non-electrolytic nature. Electronic absorption/reflectance spectra of the complexes show intra-ligand, charge transfer and crystal field transitions. Room temperature magnetic susceptibility measurements of these complexes, except Co(INPP)(Meth).H2O (where Meth = deprotonatated methionine), are indicative of a distorted octahedral geometry with some antiferromagnetic interaction. The complex Co(INPP)(Meth).H2O shows a room temperature magnetic moment of 1.46 B.M. possibly due to a large antiferromagnetic effect. The IR studies suggest bonding through the oximino nitrogen and carboxylic oxygen donors and replacement of the proton of the amino acid. All of these complexes have been screened for their antibacterial activity against selected bacterial strands using the Ditch Plate and Agar Cup methods.