Magnetism of novel Schiff-base copper(II) complexes derived from aminoacids

Synthesis and Structural Characterization of (E)-4-[(2-Hydroxy-3-methoxybenzylidene)amino]butanoic Acid and Its Novel Cu(II) Complex

A novel Cu(II) complex based on the Schiff base obtained by the condensation of ortho-vanillin with gamma-aminobutyric acid was synthesized. The compounds are physico-chemically characterized by elemental analysis, HR-ESI-MS, FT-IR, and UV-Vis. The complex and the Schiff base ligand are further structurally identified by single crystal X-ray diffraction and 1H and 13C-NMR, respectively. The results suggest that the Schiff base are synthesized in excellent yield under mild reaction conditions in the presence of glacial acetic acid and the crystal structure of its Cu(II) complex reflects an one-dimensional polymeric compound. The molecular structure of the complex consists of a Cu(II) ion bound to two singly deprotonated Schiff base bridging ligands that form a CuN2O4 chelation environment, and a coordination sphere with a disordered octahedral geometry.

On the role played by the chirality of ligands on the aggregation of heterometallic CuII -HgII complexes

Copper(II) complexes constructed from enantiopure Schiff-base ligands derived from o-vanillin and methionine or from their racemic mixture have been employed as metalloligands towards mercury(II) ions. The nature of the heterometallic Cu^II -Hg^II complexes (coordination polymers or oligonucler species), resulted from the reactions of the copper(II) complexes with HgCl₂ or HgI₂ , is different. The enantiopure metalloligands lead to chiral coordination polymers, ¹ _∞ [{Cu(R-/S-valmet)(H₂ O)}₂ HgCl₂ ]·5H₂ O·CH₃ OH and ² _∞ [{Cu₂ (R-/S-valmet)₂ (μ-H₂ O)(H₂ O)₂ }HgI₂ ]·4H₂ O. The reaction of the racemic mixture of the metalloligands with HgX₂ affords discrete complexes: [{Cu(R,S-valmet)(H₂ O)₂ }₂ HgCl₂ ]·2H₂ O and [{Cu(R,S-valmet)(H₂ O)(CH₃ OH)}₂ Hg₂ I₄ ].