Polyallylamine catalysts

The basic idea was to randomly acylate polyallylamine (MW = 50,000-65,000) all at once with eight different activated carboxylic acids. The relative amounts of acids used in the process was defined experimentally. Since the positions of attack could not be controlled, a huge family of diverse polymers (4) was formed. In separate runs the mixtures were treated with varying amounts of transition metal salts and tested in the hydrolysis reaction (1) —> (2) (Equation (1). The best catalyst performance was achieved in a particular case involving Fe3+, resulting in a rate acceleration of 1.5 x 105. The weakness of this otherwise brilliant approach has to do with the fact that the optimal system is composed of many different Fe3+ complexes, and that deconvolution and therefore identification of the actual catalyst is not possible. A similar method has been described in other types of reaction.30,31... 

The last work pertaining to the discovery of new catalysts is perhaps the most novel approach to be reported thus far. In one of the earliest approaches taken toward catalyst development, Menger et al. (61) attempted to find catalysts for phosphate ester hydrolysis. A series of eight functionalized carboxylic acids were attached to polyallylamine in various combinations. Each of these polymers were then treated with one of three metals, Mg2+, Zn2+, or Fe3+. The different members of each library were identified by the relative percentages of each carboxylic acid attached to the polyamine. For example, one polymer possessed 15% Oct, 15% Imi, 15% Phe, and 5% Fe3+. There is no attempt to identify the location of the various carboxylic acids in a given polymer. This approach is novel since each system consists of an ensemble of different ligands with the carboxylic acids positioned in various locations. Each polymer within a given ratio of carboxylic acids consists of a combinatorial library of potential catalysts. 

The basic goal behind this approach is to find systems that perform the desired reaction without particular interest in the absolute structure of the active species. In an ensemble that possesses activity, there are likely many catalysts that are not active. The analogy to catalytic antibodies is made. Just as in the polyallylamine system reported, the identity and structure of catalytic antibodies is not determined. At this time, the authors are not interested in sorting out which species are active and which are not. Their stated goal is to find a system that catalyzes the desired reaction. 

The use of peroxide sensors has been extended to the sensing of glucose, lactate, alcohol, oxalate, glutamate and other amino acids by coimmobilization of the respective oxidase on top of the peroxidase [7,8,228,229], and furthermore, to afl nity-based assays [130,131,217,273]. An octane sensor was created by layering a porphyrin type P450-mimics on a screen-printed HRP-modified carbon electrode (Fig. 2.13) [106]. The biomimetic catalyst (iron(III)-meso-tetrakis-(pentafluorophenyl)-p-tetrasulfonatopor-phyrin chloride) was linked to the electrode with polyallylamine on the basis... 

It was also investigated the behaviour of some chelates, mainly based on polyallylamine and copper. On the reduction stage, in the presence of catalyst, the copper ions change their oxidation state (Cu + Cu ) therefore the co-ordinative bonds are split and... 

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