Synthesis and characterization of some novel macrocyclic NiII complexes

Novel macrocyclic Ni II complexes were synthesized by the template reactions of different organic dicarbonyls (benzil, 2,3-butanedione and 2,6-diacetylpyridine) with the corresponding aliphatic diamines [ethylene diamine (en), diethylene triamine (tri), triethylene tetraamine (tetr) and tetraethylene pentaamine (pent)] and in the presence of NiCl 2 ·6H 2 O. All the above reactants were mixed together in the same flask using 2+2 technique to form Schiff-base macrocycle complexes. The isolated amorphous macrocyclic Ni II solid complexes have the general formulae, [Ni(L 1 )Cl 2 ]EtOH, [Ni(L 2 )Cl 2 ]1/2EtOH, [Ni 2 (L 3 )Cl 4 ], [Ni 2 (L 4 )Cl 2 ]Cl 2 ·2H 2 O, [Ni(L 5 )Cl 2 ]6H 2 O, [Ni(L 6 )Cl 2 ]3H 2 O, [Ni(L 7 )Cl 2 ]4H 2 O, [Ni 2 (L 8 )Cl 2 (H 2 O) 2 ]Cl 2 , [Ni(L 9 )Cl 2 ]Cl 2 , [Ni 2 (L 10 )Cl 4 (H 2 O) 2 ], [Ni 2 (L 11 )Cl 2 (H 2 O) 2 ]Cl 2 and [Ni 2 (L 12 )Cl 4 ]2.5H 2 O·EtOH. These complexes were characterized using chemical, molar conductance, spectral (UV–Vis, IR, 1 H-NMR, mass), magnetic and thermal measurements. The values of molar conductivities in DMF suggest that the isolated amorphous solid complexes are electrolytic and/or non-electrolytic in nature depending on the type of the synthesized ligand and the number of Ni II ions within the same complex. The IR spectra of all metal complexes indicate that the ligands behave in a tetradentate manner coordinating via the four azomethine nitrogen’s (C=N) or two azomethine nitrogen’s and two pyridyl nitrogen’s and/or two azomethine nitrogen’s and two NH groups, respectively. The values of magnetic for all Ni 2+ complexes suggest the existence of octahedral geometry around the Ni II ion in the monomeric or in the dimeric forms. In all cases the ligands form five-member rings around the Ni II ions. Also, the results of electronic spectra suggest an octahedral geometry around the Ni II ion. Moreover, the results of thermal studies indicate the mechanism of decomposition as well as the number of EtOH inside and/or outside the coordination sphere. Finally, the isolated solid ligands as well as the synthesized amorphous Ni II complexes have been applied against fungi, bacteria and DNA.