EFFECT OF THE NATURE OF SYNTHETIC SUPPORTS ON THE GEOMETRY OF SURFACE COPPER(II) COMPLEXES

Abstract

Synthetic supports and coper(II) complexes anchored on themby an incipient wetness impregnation with subsequent drying at 100 °C have been characterized by IR and UV-vis diffuse reflectance spectroscopy. As can be seen, the synthetic zeolites demonstrate IR bands corresponding to both water molecule vibrations (stretching and deformation) and stretching vibrations of the crystal framework. The 6 main absorption bands in the IR spectrum of SiO2are characteristic of stretching and deformation vibrations of OH groups, water molecules, and the bonds in Si–O–Si, Si–O, and Si–OН fragments. Absorption bands in the IR spectrum of Al2O3correspond to stretching vibrations of OH groups bound to aluminum being in its tetrahedral (AlIV) and octahedral (AlVI) configurations. As appears from the UV-vis diffuse re-flectance spectra, on all supports under study, i.e. synthetic zeolites (NaX, NaA, KA), alumo-gel, and silica gel (KSMG grade), copper(II) is situated in the mixed-ligand (H2O, Cl-) octa-hedral surroundings. A wavelength corresponding to d-d transition in the Cu(II) ion anchored to the supports under study decreases in the order CuCl2/SiO2(KSMG) (820 nm) >CuCl2/NaA (733 nm) >CuCl2/Al2O3 (720 nm) ≈CuCl2/NaХ (716 nm) >CuCl2/KA (690 nm). Thus, in addi-tion to the geometry of the surface copper(II) complexes, it has been found that the role of the support is in the short-wave shifting of the band corresponding to d-d transition in the Cu(II) ion showing a distortion in the octahedral symmetry of Cu(II) environment.

Keywords

• ІЧ-спектроскопія
• спектроскопія дифузного відбиття
• синтетичні цеоліти
• силікагель
• алюмогель
• купрум(ІІ)