Mohammed Yusuff, K K; Rani, Abraham(Elsevier,Journal of Molecular Catalysis A: Chemical 198 (2003) 175–183, December 2, 2002)
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Abstract:
Copper(II) complexes of two biologically important ligands, viz., embelin (2,5-dihydroxy-3-undecyl-2,5-cyclohexadien
1,4-dione) and 2-aminobenzimidazole were entrapped in the cages of zeolite Y by the flexible ligand method. The capability
of these compounds in catalyzing the reduction of oxygen (industrially known as deoxo reaction) was explored and the
results indicate an enhancement of the catalytic properties from that of the simple copper ion exchanged zeolite. These
point to the ability of the ligands in enhancing the oxygen binding capability of the metal ion. Elemental analyses, Fourier
transform infrared (FTIR), diffuse reflectance and EPR spectral studies, magnetic susceptibility measurements, TG, surface
area analyses and powder X-ray diffraction studies were used in understanding the presence, composition and structure of
the complexes inside the cages. The study also reveals the increased thermal and mechanical stability of the complexes as a
result of encapsulation.
Suja, N R; Mohammed Yusuff, K K(Department of Applied Chemistry, 2002)
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Abstract:
The thesis deals with the synthesis, characterization and catalytic activity studies of supported cobalt(ii), nickel(II) and copper(II) complexes of O-phenylenediamine and Schiff bases derived from 3-hydroxyquinoxaline -2-carboxaldehyde. Zeolite encapsulation and polymer anchoring was employed for supporting the complexes. The characterization techniques proved that the encapsulation as well as polymer supporting has been successfully achieved. The catalytic activity studies revealed that the activities of the simple complexes are improved upon encapsulation. Various characterization techniques are used such as, chemical analysis, EPR, magnetic measurements, FTIR studies, thermal analysis, electronic spectra, XRD, SEM, surface area, and GC.The present study indicated that the that the mechanism of oxidation of catechol and DTBC by hydrogen peroxide is not altered by the change in the coordination sphere around the metal ion due to encapsulation. This fact suggests outer sphere mechanism for the reactions. The catalytic activity by zeolite encapsulated complex was found to be slower than that by the neat complex. The slowing down of the reaction in the zeolite case is probably due to the constraint imposed by the zeolite framework. The rate of DTBC ( 3,5-di-tert-butylchatechol)oxidation was found to be greater than the rate of catechol oxidation. This is obviously due to the presence of electron donating tertiary butyl groups.