pH-Dependent Self-Assembly of Complexes with Tripodal Amino Acid Ligand

Three new metal complexes were synthesized by reactions of [bis(2-amino-ethyl)-amino]-acetic acid (HL) and different metal salts at different pH values. Their structures were characterized by X-ray crystallography. Interestingly, under acidic conditions, the dinuclear structure {Cu2[H(L)]2Cl2}(ClO4)2 (1) was obtained, whereas under alkaline conditions, the complexes {[Cu(L)](ClO4)}n (2) and [Cd(L)Cl]n (3), which exhibit distinct one-dimensional (1D) structures, were obtained. The results indicate that the pH value, metal ions, and anions have remarkable influence on the formation and structure of the complexes.