Synthesis, 2D NMR and X-ray diffraction studies on Cu(II) and Ni(II) complexes with ligands derived from azobenzene-cored Schiff base: Mesomorphic behaviors of Cu(II)–phenolates and crystal structure of bis[4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene]copper(II)

Yeap, Guan-Yeow; Heng, Boon-Teck; Kakeya, Masaki; Takeuchi, Daisuke; Górecka, Ewa; Ito, Masato M.

Synthesis, 2D NMR and X-ray diffraction studies on Cu(II) and Ni(II) complexes with ligands derived from azobenzene-cored Schiff base: Mesomorphic behaviors of Cu(II)–phenolates and crystal structure of bis[4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene]copper(II)

2011

Two new homologous series of copper(II) and nickel(II) complexes derived from bidentate Schiff bases 4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene have successfully been synthesized. Their molecular structures were elucidated by FT-IR, ¹H and ¹³C NMR along with ¹H–¹H COSY, ¹H–¹³C HMQC, ¹H and ¹³C HMBC. Mesomorphic behaviors of ligands and metal complexes have been investigated by differential scanning calorimetry and polarizing optical microscope. All ligands and their copper complexes exhibit exclusively the mesomorphic properties. The X-ray diffraction studies have confirmed the presence of smectic A (SmA) phase in copper(II)–phenolate complexes. The molecular structure of bis[4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene]copper(II) have been determined by using X-ray crystallographic techniques. It was found that the ligands have square planar configuration around the Cu center ion as evident by the NCuN and OCuO angles of 180°.

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