Metal complexation biopolymers

The hydration of propylene with sulfuric acid catalyst in high-temperature water was investigated using a flow reaction system.31 The major product is isopropanol. A biopolymer-metal complex, wool-supported palladium-iron complex (wool-Pd-Fe), has been found to be a highly active catalyst for the hydration of some alkenes to the corresponding alcohols. The yield is greatly affected by the Pd/Fe molar ratio in the wool-Pd-Fe complex catalyst and the catalyst can be reused several times without remarkable change in the catalytic activity.32... 

Lakatos, B. and Meisel, J. (1978). Biopolymer-metal complex systems. V. PMR investigation of humic substances. Acta Agron. Acad. Sci. Hung. 27, 313-320. 

The hydration of C-C multiple bonds is a reaction with prevalent industrial interest due to the usefulness of the products as chemical intermediates. The wool-Pd complex is an economical and highly active catalyst for hydration of olefins. It is very stable and can be reused several times without any remarkable change in the catalytic activity [73, 74]. In particular, to convert alkenes to the corresponding alcohols in excellent enantioselectivity, a new biopolymer-metal complex constituted of wool-supported palladium-iron or palladium-cobalt was prepared and used, such as allylamine to amino-2-propanoI, acrylonitrile to lactonitrile and unsaturated acids to a-hydroxycarboxylic acids [75-77]. The same catalytic system was also used for hydration of substituted styrenes to produce chiral benzyl alcohols. The simple and cleaner procedure, mild reaction conditions, high stability and recovery rate of catalyst made these catalytic systems an attractive and useful alternative to the existing methods (Scheme 37). 

Wang S, Zhang Z, Chi C, Wu G, Ren J, Wang Z, Huang M, Jiang Y (2008) Asymmetric hydration of ortho- or para-substituted styrenes catalyzed by biopolymer-metal complex wool-Pd. React Func Polym 68 424-430... 

Natural circular dichroism (optical activity). Although circular dichroism spectra are most difficult to interpret in terms of electronic structure and stereochemistry, they are so very sensitive to perturbations from the environment that they have provided useful ways of detecting changes in biopolymers and in complexes particularly those remote from the first co-ordination sphere of metal complexes, that are not readily apparent in the absorption spectrum (22). It is useful to distinguish between two origins of the rotational strength of absorption bands. 

Proteins are water-soluble biopolymers with a huge number of potential donor atoms and coordination sites which could make them useful carriers of metal complex catalysts. Indeed, a few successful attempts can be found in the literature [139] but often the interaction of proteins and metal complexes lead to a loss of catalytic activity [140]. This was not the case with human serum albumin (HSA) which formed a stable and active catalytically active complex with [Rh(acac)(CO)2]. In the hydroformylation of 1-octene and styrene the selectivity towards aldehydes was excellent, moreover styrene reacted with high regioselectivity (b/1 = 19). The activity... 

Used widely in synthetic macromolecular and natural biopolymer fields to evaluate structural and thermodynamic properties of macromolecular materials, thermal analytical methods have been applied to assist in the characterization of natural organic matter (NOM). Originally applied to whole soils, early thermal studies focused on qualitative and quantitative examination of soil constituents. Information derived from such analyses included water, organic matter, and mineral contents (Matejka, 1922 Tan and Hajek, 1977), composition of organic matter (Tan and Clark, 1969), and type of minerals (Matejka, 1922 Hendricks and Alexander, 1940). Additional early studies applied thermal analyses in a focused effort for NOM characterization, including structure (Turner and Schnitzer, 1962 Ishiwata, 1969) and NOM-metal complexes (e.g., Schnitzer and Kodama, 1972 Jambu et al., 1975a,b Tan, 1978). Summaries of early thermal analytical methods for soils and humic substances may be found in Tan and Hajek (1977) and Schnitzer (1972), respectively, while more current reviews of thermal techniques are provided by Senesi and Lof-fredo (1999) and Barros et al. (2006). 

The Ru11 complexes that contain polyaza-aromatic ligands, such as TAP (1,4,5,8-tetra-azaphenanthrene) and HAT (1,4,5,8,9,12-hexa-azatriphenylene) manifest the very high oxidation potential of their 3MLCT states. Therefore, under illumination, they are able to abstract an electron even from rather poor electron donors, eg biopolymers such as DNA, oligonucleotides, and oligopeptides. Other effects of the photoinduced electron transfer may be photoadduct formation and photocrosslinking via metal complexes [102],... 

ESI-MS is becoming a detection method of choice, which readily identifies the molecular composition of species separated by flowing mobile phases. For space limitations, the reviews by Stewart for separation and speciation,24 by Szpunar for metallo-biopolymers,25 by Shepherd on transition metal complexes,1,75 by Colton, D Agostino, and Traeger,76 and Henderson, Nicholson, and McCaffery77 for organometallic complexes are highly recommended. The subject of ESI-MS is also presented in Chapter 2.28. 

A developing area in separations is the use of supported metal complexes to provide sites of retardation in the mobile phase migration for more hydrophobic molecules in the separation of organic mixtures. This has been termed IMCOS, standing for immobilized metal complexes for organic separations. 1 The technique parallels the separation of hydrophilic biopolymers by the IMAC methods. Wasiak and co-workers100 have presented a good overview of IMCOS. A review on modifications to silica supports is presented in the review of Biernat et a 1... 

Based on the models of natural metal complexes synthetic metal complexes have been developed for different purposes. They consist of a synthetic polymer, which is the replacement of the biopolymer protein in the natural metal complexes, and a specific synthetic ligand that is able to bind the metal ions. The basic model of synthetic metal complexes is shown in Figure 7. 

If the chromatographic system is suitably calibrated, then size characterization of elemental species is possible. SEC is a gentle method and normally does not result in a loss of element species or on-column alterations. It plays the predominant role when separating labile and weak metal-complex-ing biopolymers (Makarov and Szpunar 1998). 

We have studied the use of HA as adsorbent. A composite biopolymer adsorbent in which HA was immobilized by a combination of calcium alginate gel membrane and activated carbon powder was developed [6,8]. Furthermore, another HA was made by a thermal process [7]. Based on a metal complexation model [7,8], the effect of immobilization and insolubilization on the metal complexing ability of HA is discussed in the following sections. 

Interaction of fluorophores with natural biopolymers such as proteins, polysaccharides, or DNA is also an enantioselective process and can be used to discriminate between two enantiomers of a specific compound. A remarkable example is the differential interaction of A and A isomers of luminescent octahedric metal complexes with DNA (metallointercalators), which generate a fluorescent signal and was shown to be dependent on the DNA heUcity, as was reversed for right-handed B-DNA and left-handed Z-DNA [38], However, in most studies, the main interest has usually been to probe the biopolymer conformation and not to generate an enantioselective fluorescence response of the probe. 

A new chitosan biopolymer derivative as metal-complexing agent Synthesis, characterization, and metal(II) ion adsorption studies Carbohydr Res. 345(14), 2013-2022. 

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