Azo-Schiff Type Ligands Derived from Curcumin and their Complexes with Transition Metals, Synthesis, Characterization and Bioactivity Studies

In this work the precursor (W1) 2,2'-((1E,1'E)-(4,4'-diamino-5,5'-dimethyl-[1,1'-biphenyl]Diazene-2,1-diyl-3,3’-diyl)-bis((E)-pyridin-3-yldiazenyl)-[1,1'-biphenyl] or (W2) 3,3'-dimethyl-5,5'-bis((E)-pyridin-3-yldiazenyl)-[1,1'-biphenyl] -4,4'-diamine respectively were obtained from the reaction of 2-aminophenol or 2-aminopyridine with toluidine, respectively. Subsequently, these precursors were used for the synthesis of two ligands using the azo compounds (W1) or (W2) and curcumin to produce [H4L1] 4,4',4'', 4'''-((1E,1'E,6E,6'E)-((3,3'-bis((E)-(2-hydroxyphenyl)diazenyl)-5,5'-dimethyl-[1,1'-bi phenyl]-4,4'-diyl)bis(azaneylylidene))bis(5-hydroxyhepta-1,6-diene-1,7-diyl-3-ylidene))bis(azaneylylidene))bis(aza -neylylidene))tetrakis(2-methoxyphenol) or [H2L2] 4,4',4'',4'''-((3,3'-dimethyl-,4,4'-diyl)bis- (azaneylylidene))bis(5-hydroxyhepta-1,6-diene-1,7-diyl-3-ylidene))tetrakis(2-methoxyphenol). The prepared ligands were characterized by F.T-I.R, U.V, 1H-NMR,13C-NMR spectroscopy. This work also included the preparation of complexes through the reaction of ligands with the metal alts of CoII, CuII, MnII, NiII and CdII ions, under reflux, using ethanol as a solvent and KOH as a base. These complexes were characterized by (I.R., U.V-Vis. and mass) spectroscopy, atomic absorption (A.A), melting point, conductivity and magnetic susceptibility measurements along with thermal analysis. Analytical and spectroscopic methods pointed to tautomerism observed in curcumin moiety. Six and four coordination shapes were suggested based on the information gathered during the characterization procedure. Certain bacteria and fungi were tested against the ligands and their complexes. All prepared compounds appeared better inhibition against fungi compared to the four types of bacteria and the results obtained suggested different effects of the complexes, but generally, the metal complexes are more effective than the free ligands against a variety of organisms under test.