Graphical Abstract: Three kinds of copper(II) complexes with 1,4,7-tris(2-aminoethyl)-1,4,7-triazacyclononane (taetacn), [Cu(taetacn)](ClO4)2 (1), [Cu(Htaetacn)](ClO4)3 (2), and [Cu(Htaetacn)](BF4)3 (3) were synthesized and characterized by elemental analyses, IR and UV-Vis spectroscopies. The spectral features are in harmony with an octahedral geometry for 1 and a square-pyramidal coordination for 2 and 3.