Mixed ligand complexes of the type [Levo.- M- (L1 - L4)], where M = Co (II), Ni(II), Cu(II) and Zr (IV), Levo. is
levofloxacin drug as a primary ligand and L1-L4 are four azo compounds as secondary ligands, were prepared and
characterized by elemental analysis, molar conductivity, FT-IR, UV-Vis spectroscopy, magnetic moments, and
thermogravimetric (TG&DTA) analysis. Spectral and elemental analysis data showed that both levofloxacin drug and the
secondary ligands azo compounds act as monovalent monodentate coordinating to the metal ion via OO fashion in
levofloxacin and through ON fashion in the secondary ligands with octahedral geometry in all cases. The crystal field
splitting energy (∆o), Racah parameter (B'), nephelauxetic ratio (β), Sinha parameter (δ %) (metal – ligand covalency
percent) and the covalency angular overlap parameter (η) have been calculated using the Tanabe Sugano diagram. The
antimicrobial activity of the mixed ligand complexes has been studied by screening against some gram positive and gram
negative bacteria, where it was found that they have enhanced activity. The antitumor activities of some selected
complexes were tested against HEPG2 cell line and compared to that of Vinblastine as a standard drug