Zinc(II) and copper(II) 1D coordination polymeric complexes of a reduced Schiff base ligand

The reaction of Zn(ClO4)2 · 6H2O and Cu(ClO4)2 · 6H2O with H3Sas (H3Sas = N-(2-hydroxybenzyl)-L-aspartic acid in water afforded the complexes [Zn6(Sas)4(H2O)8]·5H2O (1) and [Cu(HSas)(H2O)] (2), respectively, which were characterized by infrared spectroscopy, elemental analysis, thermogravimetry and single-crystal X-ray crystallography. In 1, the pentanuclear clusters formed by four H3Sas ligands and five Zn(II) metal ions are bridged by the “[Zn(H2O)4]2+” cations to form 1D polymeric chains. While in 2, the mononuclear [Cu(HSas)(H2O)] repeating units form a 1D zigzag chain and further extended by strong intermolecular hydrogen bonds to form a 2D sheet. The different coordination geometries of Cu(II) and Zn(II) show significant influence on the polymeric structures.

The reaction of Zn(II) and Cu(II) salts with N-(2-hydroxybenzyl)-L-aspartic acid (H3Sas) afforded completely two different neutral 1D coordination polymeric structures. The repeating unit in [Zn6(Sas)4(H2O)8] · 5H2O (1) is made up of hydrated Zn(II) cations and [Zn5(Sas)4(H2O)4]2− anions as shown here. On the other hand, mononuclear repeating units form 1D coordination polymer in [Cu(HSas)(H2O)].Figure optionsDownload as PowerPoint slide