Synthesis, Characterization and Antibacterial Activity of New Cu(II) and Zn(II) Complexes of Schiff Bases Derived from 9-H-Fluoren-9-one

Five Schiff base ligands bearing a 9-fluorenylidene unit, L1-L5 where (L1= N -(9H-fluoren-9-ylidene)-2-hydroxy-1-naphthohydrazide, L2= N -(9H-fluoren-9-ylidene)-3- methoxybenzohydrazide, L3= N -(9H-fluoren-9-ylidene)nicotinohydrazide, L4= N -(9H-fluoren-9-ylidene) isonicotinohydrazide, and L5=N -(9H-fluoren-9-ylidene)-2-phenylacetohydrazide) and their [Zn(L)Cl2] and [Cu(L)Cl2] complexes have been synthesized. The characterization and nature of bonding of these complexes were elucidated by elemental analyses, spectral analyses (^1H NMR, FTIR), molar conductivity measurements and thermo-gravimetric studies. Analytical and spectral data revealed that L1 coordinates to metal ions by its imine nitrogen atom and the phenolic oxygen atom with a 1:1 stoichiometry. The L2-L5 coordinates to metal ions by their imine nitrogen atom and the carbonyl oxygen atom with the same as L1 stoichiometry. Most of the free ligands and their complexes exhibit antibacterial activities against a number of pathogenic bacteria. The activities of metal complexes are found to be higher than those of the free ligands.