Abstract
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 NiCl2 center dot 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 center dot 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(H2O)(2)]Cl-2, [Ni(L-9)Cl-2]Cl-2, [Ni-2(L-10)Cl-4(H2O)(2)], [Ni-2(L-11)Cl-2(H2O)(2)]Cl-2 and [Ni-2(L-12)Cl-4]2.5H(2)O center dot EtOH. These complexes were characterized using chemical, molar conductance, spectral (UV-Vis, IR, H-1-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 Ni2+ 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.