Synthesis and structural characterization of new [Cu^II-TiO₂] composites from Cu^II-salen as precursors

Five salen type copper(II) complexes [CuL¹] (1), [CuL²] (2), [CuL³] (3), [CuL⁴] (4) and [CuL⁵] (5) and their composites with TiO₂, [CuL¹-TiO₂] (6), [CuL²-TiO₂] (7), [CuL³-TiO₂] (8), [CuL⁴-TiO₂] (9) and [CuL5- TiO₂] (10) were synthesized and characterized by employing elemental analysis, infra-red (IR) and TD-DFT calculations. The solid state structures of (4) and (5) were confirmed using X-ray diffraction on single crystals. The structural analyses of composites (6-10) along with TiO₂ were performed through X-ray photon spectroscopy (XPS) and powder X-ray diffraction (P-XRD). X-Ray analysis demonstrated that the Cu²⁺ ion in complex (4) acquire distorted square planer geometry and occupy inner chamber (N₂O₂) of the Schiff base ligand whereas in complex (5) two mononuclear units are connected by phenoxo bridge to form a dimer in which Cu²⁺ ions exhibits a five-coordinated square pyramidal coordination geometry. The methoxy groups are free in both complexes. The XPS measurements on composite (9) shows that change of dipole moment due to chemical adsorption, which affect electronic state of TiO₂. The measurement results of P-XRD have been analyzed by employing Rietveld analysis method and a change in volume of TiO₂ for composite (9) is observed.