Noncyclic Diaza Ligands and Their Metal Complexes: Synthesis, Characterization, and Biological Studies

Abstract

Condensation reactions involving various ketones and amines formed noncyclic ligands denoted as LI, LII, LIII, and LIV. Ethylenediamine, when reacted with acetophenone, benzoylacetone (in the presence of 70% HClO4), and benzophenone, resulted in the following noncyclic ligands: (E,E)-N,N-bis(1-phenylethylidene)ethylenediamine (LI), bis(1-3-hydroxy-3-phenylbut-2-ene-ylidene) (LII) and (E,E)-N,N-bis(1,1-diphenylmethylidene)ethylenediamine (LIII), respectively. The reaction of benzophenone with 1,3-diaminopropane in a 1:1 ratio in a methanolic solution also led to the synthesis of a noncyclic ligand, (E,E)-N,N-bis(1,1-diphenylmethylidene)propylenediamine (LIV). All the synthesized noncyclic ligands, except LII, undergo decomposition during complexation, reverting to the initial ketones and amines. In contrast, LII exhibits remarkable stability and can form square planar complexes with Ni(II), Cu(II), and Co(II) salts. Additionally, the Co(II) complex can convert into a six-coordinated Co(III) complex, [CoLII(H2O)2](NCS), when it reacts with KNCS. All these ligands and derived metal complexes were characterized, and their antimicrobial properties were evaluated against the selected fungi and bacteria.