Polyoxometalates encapsulation

Juan-Alcaniz J, Goesten MG, Ramos-Femandez EV, Gascon I, Kapteijn F. Towards efficient polyoxometalate encapsulation in MlL-100(Cr) influence of synthesis conditions. New 1 Chem 2012 36 977-87. 

Scheme 9.17 Lipophiloselective reactions with polyoxometalates encapsulated in cross-linked polyethyleneimine.

Xing X, Liu R, Yu X, Zhang G, Cao H, Yao J, Ren B, Jiang Z, Zhao H (2012) Self-assembly of CdS quantum dots with polyoxometalate encapsulated gold nanoparticles enhanced photocatalytic activities. J Mater Chem A 1 1488-1494... 

The structure of [(Y0H2)3(C03)(A-a-PW9034)2]" [25]. (Reprinted with permission from T.M. Anderson, W.A. Neiwert, and C.L. HiU, Yttrinm polyoxometalates. Synthesis and characterization of a carbonate-encapsulated sandwich-type complex, Inorganic Chemistry, 42, no. 26, 8600-8602 (Figure 1), 2003. 2003 American Chemical Society.)... 

Li, H., Qi, W, Li, W. et al. (2005) A highly transparent and luminescent hybrid based on the copolymerization of surfactant-encapsulated polyoxometalate and methyl methacrylate. Advanced Materials, 17, 2688-2692. 

The use of MIL-lOl-encapsulated polyoxometallate (POM) has also been reported for the a-oxidation of cyclohexene and a-pinene [113]. Both Ti- and Co-POM/MIL-101 catalysts showed fairly good activity and selectivity toward a-pinene oxidation with 40% and 45% conversion, respectively, and an average selectivity of 30% for both verbenol and verbenone compared with unmodified MIL-101 (14-18% conversion). 

Sun, H., Li, H.L., Wu, L.X. Micro-patterned polystyrene surfaces directed by surfactant-encapsulated polyoxometalate complex via breath figures. Polymer 50, 2113-2122 (2009)... 

Some of these surfactant-encapsulated polyoxometalate complexes exhibited liquid-crystaUine behavior. Paul and coworkers obtained room temperature LCs by complexation of the sandwiched europium-containing polyoxometalate [Eu(SiW9Mo2039)2] with a series of cationic surfactants (Zhang et al., 2005). For the quaternary ammonium cations with one long chain a hexagonal (columnar ) phase and possibly a cubic phase were observed, whereas for the quaternary ammonium cation with two long chains... 

More recent methods are described subsequently Glycohc acid can be synthesized by contacting carbon monoxide and formaldehyde with a catalyst containing an acidic polyoxometalate compound encapsulated within the pores of a zeohte. The zeohte has cages larger than the addic polyoxometalate compoimd, and has pores with a diameter smaller than the diameter of the acidic polyoxometalate compound (38). 

Lu X, Liu X, Wang L, Zhang W, Wang C (2006) Fabrication of luminescent hybrid fibres based on the encapsulation of polyoxometalate into polymer matrices. Nanotechnology 17 3048-3053... 

Different types of species have been successfully encapsulated inside MOFs through use of any of the three methods desalbed above. These species include metal nanoparticles, metal oxides, quantum dots, polyoxometalates, polymers, graphene, carbon nanotubes, biomolecules, and so on. A brief overview of the systems prepared so far is given below. 

As a consequence of showing that alkylated polyethyleneimines can facilitate aqueous biphasic catalysis, we extended the concept by the preparation of a cross-linked polyethyleneimine assembly that encapsulated a polyoxometalate catalyst, which resulted in the Upophiloselective oxidation of secondary alcohols (Scheme 9.17) [152]. Thus, even though reactions were carried out in water, competitive oxidation of a more hydrophobic alcohol in the presence of a hydrophilic alcohol significantly favored the former. The lipophiloselectivity was proportional to the relative partition coefficient of the substrates. 

The structural and spectroscopic features of the photoactive complex are preserved inside the polymeric film, as confirmed by UV-vis spectra. In addition, SEM analysis of both the film surface and cross-section highlight a well-dispersed, homogeneous distribution of the catalyst domains, which appear as spherical particles of approximately 1-2 xm in diameter. The structural similarity of (RfN)4Wio032 with other surfactant encapsulated polyoxometalates (SEPs) suggests the formation of organized domains, similar to spherical onion-like vesicles. ... 

Qi, W., Li, H. and Wu, L. (2008). Stable Photochromism and ControUable Reduction Properties of Surfactant-Encapsulated Polyoxometalate/Silica Hybrid Films, J. Phys. Chem. B, 112, pp. 8257-8263. 

Li, H., Li, R, Yang, Y, etal. (2008). Incorporation of Polyoxometalates into Polystyrene Latex by Supramolecular Encapsulation and Miniemulsion Polymerization, Macromol. Rapid Commun., 29, pp. 431 36. 

Cuan J, Yan B (2013) Cool-white light emitting hybrid materials of resin-mesoporous silica composite matrix encapsulating europium polyoxometalates through ionic liquid linker. RSC Adv 3 20077-20084... 

Encapsulated Water Molecules in Polyoxometalates Insights from Molecular Dynamics... 

We have also smdied how the stability of the isomer can be modulated by the presence of different heteroatoms. As a first step, we have evaluated the relative stability of the isomers considering only the [Wig054] cage without the internal anions [(X04)2] . As shown in Table 10.4, there are two groups with different stability order isomers a, y, P and around 3 kcal mol less stable we have isomers P, a and y. The relative stability of the polyoxometalate isomers is significantly altered after encapsulating the two [XO4] anions. 

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