Synthesis, crystal structure, and properties of supramolecular Cu II, Zn II, and Cd II complexes with Salen-type bisoxime ligands

Abstract

Three new supramolecular complexes, [Cu(L 1)H 2O] n ( 1), [Zn(L 2)(H 2O) 2] n ( 2), and [Cd(L 2)(H 2O) 2] n ( 3), have been synthesized and characterized by FT-IR spectra, fluorescence spectra, and thermal analyses. And the structures of complexes 1– 3 have been elucidated by X-ray analyses. Complex 1 is square pyramidal geometry with an unusually long bond (2.262 Å) from penta-coodinated Cu II center to the oxygen atom of the apical coordinated water molecule. Molecules are linked by hydrogen bonding between the coordinated water and the phenolic oxygen atoms of adjacent molecules, thus formed a self-assembling continual zigzag chain supramolecular structure. The crystal structure of complex 2 (or 3) has indicated that the complex consists of one Zn II (or Cd II) atom, one L 2− unit and two coordinated water molecules, the coordination number of the Zn II (or Cd II) atom is six, and formed an infinite metal–water chain supramolecular structure by intermolecular hydrogen bonds and π–π stacking of neighboring benzene rings. Meanwhile, the thermal and photophysical properties of the resulted complexes have also been discussed.