Norbornene Oxidation by Chiral Complexes Encapsulated in NaY Zeolite

Abstract

The preparation of chiral metal complexes in NaY zeolite is reported. The guests, chiral metal complexes, were entrapped in the supercages of NaY zeolite (host) by a two-step process in the liquid phase: (i) inclusion of the selected transition metal (rhodium(III) and manganese(II)) by ion-exchange in the porous structure and (ii) introduction of the chiral ligand, an d-erythrose amino derivative, namely (2R,4S,5R)-4-[(N-methylamino)methyl]-2-phenyl-1,3-dioxan-5-ol, followed by assembly of the complex inside the void space of the zeolite. Structural (FTIR and XRD), surface studies (SEM) and chemical analyses were used to characterize the new host–guest catalysts and the results indicated that chiral metal complexes were successfully encapsulated in supercages of the NaY zeolite. Catalytic studies were performed in liquid phase for norbornene oxidation using tert-butyl hydroperoxide as the oxygen source. The catalytic results were compared with styrene and cyclohexanol oxidation as model reactions. The prepared chiral catalysts exhibited catalytic activity for all oxidation reactions. The stability of the catalysts before and after reaction was confirmed by cyclic voltammetry and FTIR studies.

Fenton-Type Bimetallic Catalysts for Degradation of Dyes in Aqueous Solutions

“…Cyclic voltammetry (CV) studies provide qualitative information on the electrochemical response of prepared bimetallic catalysts with respect to electrochemical reactions in the stability region of the solvent. Cyclic voltammograms of the NaY/CT electrode in the same medium without any oxidation or reduction peaks were given in our previous works, confirming that no significant redox process takes place on support material alone [21,22]. As expected, in the potential region of −1.5 to 1.5 V vs. SCE (Saturated Calomel Electrode) used in this work, the parent zeolite does not present any electroactive species.…”

Photocatalytic degradation of Rhodamine B dye by cotton textile coated with SiO2-TiO2 and SiO2-TiO2-HY composites

“…This spectrum also exhibits a weak band at 936 cm À1 related to SiÀ ÀOÀ ÀTi bonds, but this band was not detected in any SiO 2 -TiO 2 -HY composites, because probably it is overlapped by the intense bands of the zeolite structure. The strong bands assigned to the HY zeolite are present in all FTIR spectra of SiO 2 -TiO 2 -HY composites, namely: 461, 575, 723, 791, 1033, 1633 and 3433 cm À1 are identified in [46], except the first one that corresponds to bending modes of SiÀ ÀOÀ ÀSi linkage [47]. Only for the STH-750 composite, the bands at 791 and 723 cm À1 disappeared and new bands appeared at 784 and 671 cm À1 , which can be attributed to TiO 2 anatase phase [47] and TiÀ ÀO [17], respectively.…”

Aqueous-Phase Cellulose Hydrolysis over Zeolite HY Nanocrystals Grafted on Anatase Titania Nanofibers

“…Typical peak of Ti-O was detected at about 946 cm -1 and 813 cm -1 in titania nanofibres, however, this peak was not detected in HY-TiO 2 -80, HY-TiO 2 -100, HY-TiO 2 -120 and HY-TiO 2 -140, because it may be overlapped by the strong band of the zeolite HY nanocrystals on the titania nanofibres. 30,31 Besides, The broad peak at 3450 cm -1 and 1629 cm -1 were assigned to the stretching vibration and bending vibration of O-H bond in absorbed water respectively, 32,33 while the weak peak at around 2924 cm -1 is probably assigned to carbonaceous contaminants. 34 Hence, all these observations are consistent with the XRD results, indicating that the zeolite HY nanocrystals are well grafted onto the titania nanofibres.…”