Immobilization layered double hydroxides

Layered materials are of special interest for bio-immobilization due to the accessibility of large internal and external surface areas, potential to confine biomolecules within regularly organized interlayer spaces, and processing of colloidal dispersions for the fabrication of protein-clay films for electrochemical catalysis [83-90], These studies indicate that layered materials can serve as efficient support matrices to maintain the native structure and function of the immobilized biomolecules. Current trends in the synthesis of functional biopolymer nano composites based on layered materials (specifically layered double hydroxides) have been discussed in excellent reviews by Ruiz-Hitzky [5] and Duan [6] herein we focus specifically on the fabrication of bio-inorganic lamellar nanocomposites based on the exfoliation and ordered restacking of aminopropyl-functionalized magnesium phyllosilicate (AMP) in the presence of various biomolecules [91]. 

Jacobs, P.A. (1997) The Immobilization of Sulfonated Ru-EINAP Chloride by Anion Exchange on Layered Double Hydroxides, Studies in Surface Science Catalysis,... 

Scheme 11 C16 telomer formation by coupling of two C8 chains proposed by Parvulescu et al. for a Pd/TPPTS catalyst immobilized on a layered double hydroxides (LDH)...

Parvulescu et al. noted an interesting change in EG telomer product selectivity upon immobilization of an Pd/TPPTS catalyst on a basic support [58]. In an attempt to address the issues associated with recovery and reuse of the telomerization catalyst, the anionic TPPTS ligand was immobilized on various layered double hydroxides by ion exchange methods (Scheme 11). The use of these catalysts in the telomerization of methanol and ethylene glycol resulted in a remarkable shift in... 

Immobilization of a sulfonated chiral manganese-salen catalyst on a fimctio-nalized Merrifield resin yielded a remarkably active epoxidation catalyst [42]. Its activity and enantioselectivity was examined by epoxidation of 6-cyanochromene, indene, styrene, 4-methylstyrene, and trans-stilbene using m-CPBA/NMO and quantitative yields were obtained in less than 5 min. Enantioselectivities were between 33% (4-methylstyrene) and 96% ee (6-cyanochromene). The same complex was also supported on silica and a layered double hydroxide (LDEI) and the catalytic performances of the systems were compared. Recycling experiments were carried out and the silica-based system showed metal leaching combined with a significant decrease in yield and ee. The layered double hydroxide- and resin-catalysts exhibited a slight decrease in activity and constant ee values in five consecutive reactions. 

Catalytic oxidations by in situ generated peroxotungsten complexes immobilized on layered double hydroxides (LDH) Relation between catalytic properties and peroxotungstate micro-environment... 

The Immobilization of Sulfonated Ru-BINAP Chloride by Anion Exchange on Layered Double Hydroxides... 

AE have also been achieved by using a chiral Mn-salen complex immobilized on mesoporous materials,polymer supports," layered double hydroxides,clays,and zeolites. 

Mousty, C., Vieille, L., Cosnier, S. Laccase immobilization in redox active layered double hydroxides A reagentless amperometric biosensor Biosens. Bioelectron. 22(8), 1733-1738 (2007). doi 10.1016/j.bios.2006.08.020... 

Several years ago Pena-Cabrera et al. [32] described the use of an apparently heterogeneous catalyst system, namely, Pd/C (0.5%)/CuI (10%)/Ph3As (10%) this system was suited for use in a number of different couplings and has been applied to the reaction between 4-iodoacetophenone and 2-(tributylstannyl)thiophene [33]. Choudary et al. prepared palladium nanoparticles immobilized on layered double hydroxide [LDH-Pd(O)] for the StiUe couphng of poorly reactive chloroarenes in nonaqueous ionic liquids under microwave irradiation. The catalyst can be quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles [34]. 

This biosensor was based on the immobilization of PPO within layered double hydroxides (LDHs), which are known to be efficient immobilization matrices for this enzyme [26]. LDHs are synthetic solids with positively charged bracite-like layers of mixed metal hydroxides separated by interlayered hydrated anions. 

Co(salen) immobilized on silica, layered double hydroxides and NaX zeolite act as photocatalysts for the oxidation of 2-mercaptoethanol and sodium thiosulfate" . 

Immobilized cobalt(II) and zinc(II)phthalocyanine anchored on silica or intercalated in the galleries and cavities of layered double hydroxides (hydrotalcite) and NaX zeoMte catalyze or photocatalyze the oxidation of 2-mercaptoethanol and sodium thiosulfate. The activity of the immobilized catalysts for oxidation and photooxidation is lower than that of the complexes in homogeneous phase. This is due to the hindered diffusion of dioxygen and sulfur-containing compounds to the active catalyst sites. 

An amperometric biosensor, based on the immobilization of Horseradish peroxidase (HRP) into redox active [Zn-Cr-ABTS] (ABTS, 2,2 -azinobis 3-ethylbenzothiazoline-6-sulfonate) layered double hydroxide, was applied to the determination of cyanide [55]. The detection of cyanide is performed via its noncompetitive inhibiting action on the... 

An amperometric biosensor based on immobilization of polyphenol oxidase (PPO) into Zn-Al layered double hydroxides, also called anionic clays, was applied for the determination of cyanide [60]. The detection of cyanide was performed via its inhibiting action on the PPO electrode. Measurement was carried out with 3,4-dihydroxyphenylacetic acid as enzyme substrate, the eirzymatically generated quinoid products being electroreduced at 0.2 V. An extremely sensitive detection limit (0.1 nM) was obtained for cyanide. Enzyme immobilization into anionic exchanger clay seems to cause an increase in cyanide inhibition effects because of anion accumulation in the clay matrix. 

Recently Liu et al. reported on a series of self-assembled polyoxotungstates modified with heteroatoms such as Zn, Co, Mn, that were directly immobilized into hydrotalcite-like layered double hydroxides (LDH) by a selective ion exchange method. Sandwich-type POM species were found to be more favorable than Keggin-type POM for the direct immobilization in LDH, because strict pH control was not needed and the LDH hosts can be kept intact. The resulting LDH-POM catalysts... 

Hydrotalcite catalysts or layered double hydroxides as catalysts are reported to give high conversion and yields in transesterification of triglycerides. Development of hydrotalcite materials for immobilization of biocatalysts for transesterification can overcome the need for higher temperature for hydro-talcite-catalyzed transesterification, which usually requires higher molar ratio of methanol. Table 12.5 summarizes the applications of hydrotalcite and hydrotalcite like compoimds as heterogeneous base catalysts for the production of biodiesel. 

Gong JM, Guan ZQ, Song DD (2013) Biosensor based rai acetylcholinesterase immobilized onto layered double hydroxides for flow injection/amperometric detection of organophosphate pesticides. Biosens Bioelectron 39(l) 320-323. doi 10.1016/j.bios.2012.07.026... 

Guerard-Helaine, C., Legeret, B., Fernandes, C., Prevot, V., Forano, C., and Lemaire, M., Efficient immobilization of fructose-6-phosphate aldolase in layered double hydroxide Improved stereoselective synthesis of sugar analogues. New ]. Chem. 2011, 35, 776-779. 

Benaissi K, Helaine V, Prevot V, Forano C, Hecquet L. Efficient immobilization of yeast transketolase on layered double hydroxides and application for ketose synthesis. Adv. Synth. Catal 2011 353 1497-1509. 

A chiral sulfonato-Mn(Salen) catalyst has been incorporated into cationic Zn-Al layered double hydroxides (Scheme 10.16) [85]. This heterogeneous Mn(Salen) catalyst was highly active and enantioselective for the asymmetric epoxidation of various substituted styrenes and cyclic aUcenes. As for the asymmetric epoxidation of 1-methylcyclohexene, 94% conversion with 90% selectivity to epoxide and 68% ee were obtained. The catalysts immobilized in the layered supports could be as effective as the molecular catalysts, and be easily separated and recycled. 

Scheme 10.16 Ch iral sulfonato-Salen-Mn(lll) complex immobilized in cationic Zn-AI layered double hydroxides for the asymmetric epoxidation of various...

Kovanda et al. [67] have employed not only the voltammetry of immobilized microparticles but also several solid-state analytical techniques when studying the thermal behavior of a layered Ni-Mn double hydroxide. The important advantage of these electrochemical experiments was that they proved the presence of substantial amounts of amorphous compounds. Moreover, distinct signals could be identified for the reductive dissolution of the different phases. 

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