Supercage of zeolite

Starting from the Pt-cinchona modified system, more recently an interesting concept has been developed by Feast and coworkers [144], A chiral acidic zeolite was created by loading one molecule of iM,3-dithianc-l-oxide per supercage of zeolite Y, either during or after the zeolite synthesis. Other chiral zeolites were formed by adsorbing ephedrine as a modifier on zeolites X and Y for the Norrish-Yang reaction [145],... 

These "ship-in-bottle" complexes have been used for the oxidation of several types of organic substrates. TMPc complexes encaged in supercages of zeolite Y and X have an improved stability and activity compared to nonsupported complexes, as is shown in Table 4. 

In 1995, Maciel and co-workers (118) synthesized the trityl cation in the supercages of zeolite HY by a clever application of Friedel-Crafts chemistry—13CC14 was reacted with an excess of benzene (Fig. 15). Maciel and co-workers carried out a number of spectroscopic and chemical manipulations that unambiguously demonstrated that the product was the trityl cation and that the cation was in the zeolite. Ab initio calculations at various levels of theory predict that the point group of isolated 16 is D3 rather than Dih. It is interesting to speculate about the extent to which the zeolite environment might force the degree of twist away from the gas-phase equilibrium value. 

In the present work, the construction of a mimic of cytochrome P-450 is attempted by in situ synthesis of iron-phthallocyanines in the supercages of zeolite Y and in the channels of VPI-5. Its catalytic activity and selectivity is tested in the oxyfunctionalization of n-alkanes with tertiary butyl hydroperoxide. 

Fig. 2. Representation of the FePc molecule and its deformation in the supercage of zeolite Y (axis A downward rotation and axis B upward rotation) and in VPI-5 (axis C is parallel to the channel axis).

Fe + -Y, ferricenium-Y, ferrocenium-Y as well as H2Pc impregnated on NaY are inactive, indicating that the low amounts of FePc present in the supercages of zeolite Y are the active sites. 

In 2002, a-oxoamides have been reported to be transformed into (3-lactams via photochemical rearrangement [172]. Good results were obtained via irradiation of ionic and covalent chiral auxiliary-containing reactants in the crystalline state and in the interior supercages of zeolites (Scheme 73). 

Through the analysis of adsorption isotherms and 129Xe NMR results of the co-adsorbed xenon, we have shown that the dispersal of benzene molecules depends on not only the cation distribution but also the amount of benzene adsorbate within the supercage of zeolite adsorbents. We have also demonstrated for the first time that this well known indirect technique has the capability not only to probe the macroscopic distribution of adsorbate molecule in zeolite cavities but also to provide dynamic information about the adsorbate at the microscopic level. Conventional H and 13C NMR which directly detect the adsorbate species, although providing complimentary results, are relatively less sensitive. 

The decomposition of Co2(CO)8 in faujasites has been studied in some detail. Low-temperature spin-echo ferromagnetic nuclear resonance spectroscopy shows that very small Co particles are formed in supercages of zeolite NaX by microwave plasma activation at low temperatures (86). In situ far-infrared spectroscopy revealed that adsorbed Co2(CO)s interacts with accessible supercage cations in NaY and CoY (239). Carbonyl complexes of different Co nuclearity, such as Co4(CO)i2 and Co(CO)4, are also formed (227,228). In HY the Co atoms are oxidized to Co ions by the zeolite protons. 

Palladium, rhodium and ruthenium complexes of the Schiff base salen are synthesized in the supercages of zeolite Y. The existence of intracrystalline transition metal-salen complexes is verified by a detailed physicochemical characterization. The catalytic properties of the prepared host/guest inclusion compounds are explored in the hydrogenation of hexene-(l) or an equimolar mixture of hexene-(l) and 2,4,4-trimethylpentene-(l). 

Hexadecafluorophthalocyanine (FiePc) complexes of Ru(II) which were prepared by the reaction of tetrafluorophthalonitrile and Ru3(CO)i2, have been encapsulated in the supercages of zeolites NaX. The X type zeolites were synthesized around the RuFiePc complexes. The zeolites modified with the metal complexes were characterized by XRD, FT-IR and UV-Vis spectroscopy as well as elemental analysis. The oxidation of cyclohexane using t-butylhydroperoxide was catalyzed by the intrazeolite RuFiePc complexes. Complete conversion to cyclohexanone and cyclohexanol was achieved with nearly 3000 turnovers per day. These ship-in-a-bottle RuFisPc complexes show no signs of deactivation in contrast to the iron analogs, regardless of how the peroxide is administered during the reaction. 

Laine, P, Lanz, M., and Calzaferri, G. 1996. Limits of the in situ synthesis of lris(2,2 - bipyridine) ruthenium(II) in the supercages of zeolite Y. Inorganic Chemistry 35, 3514—3518. Langer, S.H., and Yurchak, S.J. 1969. Electrochemical reduction of the Benzene Ring by elec-... 

Schiff s base complexes of vanadium were encapsulated in the supercages of zeolite NaY and their catalytic activities were tested in the epoxidation of several alkenes and allylic alcohols with /er/-butylhydroperoxide The complexes investigated were VO(HPS) (vanadyl-N-(2-hydroxyphenyl)salicylideneimine) and VO(salen) (vanadyl-N,N (bis)salicylidene-imine). Particular attention was devoted to the question of leaching of vanadium during reaction. 

Figure 1. Hydrocarbon 02 collisional pair in a supercage of zeolite Y.

Figure 1. (b) molecular graphics picture of the supercage of zeolite Y, occupied by a Mn (bpch) complex. 

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