pH-dependent self-assembly of copper(II) complexes with a new imidazole-containing polyamine ligand: Synthesis, structure and magnetic property

Four copper(II) complexes were synthesized by reactions of new imidazole-containing polyamine ligand N1-(2-aminoethyl)-N1-(1H-imidazol-4-ylmethyl)-ethane-1,2-diamine (HL) with Cu(ClO4)2 · 6H2O under different pH and their structures were characterized by X-ray crystallography. Interestingly, the complexes have diverse structures from protonated ligand [H3(HL)][CuCl4] · Cl (1), dinuclear [Cu2(HL)2Cl](ClO4)3 · H2O (2), one-dimensional chain polynuclear {[Cu(L)](ClO4)}n (3) to cyclic-tetranuclear [Cu4(L)4](ClO4)4 · 3CH3CN (4) coordination compounds by varying reaction pH from acidic to basic. The results indicate that the reaction pH has great impact on the formation and structure of the complexes. The magnetic measurements show that there are antiferromagnetic interactions between the Cu(II) centers with g = 2.09, J = −39.0 cm−1 and g = 2.17, J = −36.8 cm−1 for 3 and 4, respectively.

Graphical abstractFour copper(II) complexes were synthesized by reactions of new imidazole-containing polyamine ligand with Cu(ClO4)2 · 6H2O under different pH and their structures were found to be from protonated ligand, dinuclear, one-dimensional chain polynuclear to cyclic-tetranuclear coordination compounds by varying reaction pH from acidic to basic. The results indicate that the reaction pH has great impact on the formation and structure of the complexes. The magnetic property of the complexes was investigated.Figure optionsDownload full-size imageDownload as PowerPoint slide