Enhanced Catalytic Activity of Zeolite Encapsulated Fe(III)-Schiff-Base Complexes for Oxidative Coupling of 2-Napthol
详细信息 查看全文
- 作者：Kusum K. Bania ; Dipsikha Bharali ; B. Viswanathan ; Ramesh C. Deka
- 刊名：Inorganic Chemistry
- 出版年：2012
- 出版时间：February 6, 2012
- 年：2012
- 卷：51
- 期：3
- 页码：1657-1674
- 全文大小：987K
- 年卷期：v.51,no.3(February 6, 2012)
- ISSN：1520-510X
文摘
Iron(III) Schiff-base complexes of general formula [Fe(L)2Cl]路2H2O, where L = N,艃-bis(salicylidene)ethylenediamine and N,Ń-disalicylidene-1,2-phenylenediamine have been encapsulated within various alkali exchanged zeolites viz. LiY, NaY, and KY by flexible ligand method. The encapsulated complexes are characterized by EDX, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), FT-IR, UV鈥搗is, diffuse reflectance spectroscopy (DRS), electron spin resonance spectroscopy (ESR) and cyclic voltammetry studies. The diffuse reflectance UV鈥搗is spectra of encapsulated complexes show a dramatic red shift of the charge transfer band with increasing electropositivity of the exchangeable cations. The electrochemical analysis predicts the shifting of the reduction potential toward negative values with increasing size of the alkali exchanged cations. The zeolite encapsulated Schiff-base complexes of iron are found to be catalytically active toward the oxidative coupling of 2-napthol. Metal complexes incorporated in potassium exchanged zeolite-Y are found to be more effective for catalytic conversion of 2-naphthol to binaphthol and induces higher selectivity toward the R-conformation. The catalytic conversion of 2-napthol to BINOL is found to depend on the reduction potential of the catalyst, with a more negative reduction potential being better for the catalytic conversion. Density functional calculation is being carried out on both the neat Fe-Salen and Fe-Salophen complexes and those encapsulated in NaY zeolite to investigate change in structural parameters, energies of the HOMO and LUMO, and global hardness and softness. Fukui functions, as local descriptors, are used to analyze the hard鈥揾ard interaction at a particular site of the complexes.