Imidazole-containing polymers

In this section, we restrict ourselves to the polyelectrolyte catalyst. A large number of investigations on imidazole-containing polymers has been reported. The readers are referred to other review articles6,106 l07). 

Imidazole-containing polymers and copolymers have been obtained from a variety of derivatized imidazoles, including the unsubstituted 1-, 2- and 4(5)-vinylimidazole monomers. Primary interest in these polymers has centered around metal complexation, ion exchange and catalytic properties. 

In the area of catalysis, the esterolysis reactions of imidazole-containing polymers have been investigated in detail as possible models for histidine-containing hydrolytic enzymes such as a-chymotrypsin (77MI11104). Accelerations are observed in the rate of hydrolysis of esters such as 4-nitrophenyl acetate catalyzed by poly(4(5)-vinylimidazole) when compared with that found in the presence of imidazole itself. These results have been explained in terms of a cooperative or bifunctional interaction between neighboring imidazole functions (Scheme 19), although hydrophobic and electrostatic interactions may also contribute to the rate enhancements. Recently these interpretations, particularly that depicted in Scheme 19, have been seriously questioned (see Section 1.11.4.2.2). 

A combined catalyst such as imidazole-containing polymer and imidazole acylated by a long chain acyl group gives a similar result in the hydrolysis of 3-nitro-4-acyloxy benzoic acid (8) (72). 

Table 9. Rates of polymerization of phenylalanine NCA and its derivatives by some imidazole-containing polymers...

Catalysis by Water-Soluble Imidazole-Containing Polymers... 

References concerning research studies of enyzme-like polymers conducted during the period of 1978-1982, catalytic properties of water-soluble imidazole-containing polymers during ester hydrolysis, as well as the latest achievements in the manufacture and application of high-molecular weight catalysts containing thiocrown-ethers or crown-sulfides, can be found in previous reviews [199-201]. 

Cationic nanocarriers are prepared from natural or synthetic polymers. The most widely used cationic polymers have been reported as PEI, PLL, poly-methacrylates (PMA), chitosan and cationic modifications of other polymers such as cyclodextrin, gelatin and imidazole-containing polymers. ... 

The proton sponge effect was first proposed by Behr and co-workers. The proton sponge nature of PEI and other materials, which display relatively high transfection efficiencies, such as lipopolyamines, PAMAM den-drimers and various imidazole-containing polymers, is thought... 

Miller M, Sherrington D. Alkene epoxida-tions catalyzed by Mo(VI) supported on imidazole-containing polymers II. Recycling of polybenzimidazole-supported MO(VI) in the epoxidation of cyclohexene. J Catal 1995 152(2) 377-83. 

COOPERATIVE INTERACTION OF ANIONIC DYES WITH IMIDAZOLE-CONTAINING POLYMERS... 

The functions of polymers formed from disubstituted acetylenes have also been studied extensively (Chart 3.6). Kwak et al. found that poly(diphenylacetylene) derivative 21 showed strong blue-green emission. Hsu and coworkers fabricated an LED composed of ITO/PEDOT/ diphenylacetylene copolymer 22/Ca/Al and observed very high device performance with a maximum luminescence of 4230 cd/m at 14 V and a maximum current efficiency of 3.37 cd/A at 7 Imidazole-containing polymer 23 can be prepared from a chlorine-bearing polymer. The fluorescence of 23 is quenched by a trace amount of Cu , but not when also... 

Poly(vlnylimidazole) Derivatives.—The hydrolysis of esters catalysed by imidazole-containing polymers has been reviewed. ... 

We will describe in this section examples of this last type of polymer, in particular imidazole-containing polymers, which have esterolytic properties and in many ways resemble serine proteases (169). 

Leonhardt et al were able to show a specific hydrolytic effect when treating nitrophenyl esters with an MIP imprinted with pyridine derivatives of N-boc-amino acids using DVB and 4(5)-vinylimidazole as monomers in combination with chelated Co ions. Compared to the control polymer, hydrolysis was accelerated by a factor of 4 to 5, while a comparison with MIP imprinted with other pyridine derivatives of N-boc-amino acids only gave an acceleration of the reaction by a factor of 2 to 3. Robinson et al used phosphonates as TSA and showed a catalytic effect of an MIP imprinted with p-nitrophenylmethyl phosphonate, using 4(5)-vinylimidazole and Co ions, on the hydrolysis of p-nitrophenol acetate. The authors— aware of the fact that imidazole containing polymers in general exhibit catalytic effects—could nevertheless demonstrate that the imprinted specimens were of 60% higher activity than the control polymers. 

Kunitake, T., Tanaka, Y., Shinkai, S. Hydrolysis by imidazole-containing polymer catalysts. Read at the 19th Annual Meeting of the Society of High Polymers, Japan, 1970, May. Tokyo, Preprint p. 147. 

Imidazole-containing polymers designed on the basis of histidine have been reported to have a proton-sponge property and enhanced release of complexes into the cytoplasm following adsorptive pinocytosis [62]. 

This review article summarizes our more recent investigations of the esterolytic action of water soluble imidazole containing polymers. In our previous work we have explained increased reactivity of polymeric reactants in terms of electrostatic and cooperative effects. Recently, we have directed our efforts in emphasizing the apolar interaction as it has reflected dramatic rate enhancements and proven a predominant factor in determining the maximum catalytic efficiency. Polymeric catalysts which are included in this review are poly[l-alkyl-4(5)-vinyl-imidazoles] and their copolymers, hydro-phobic terpolymers of 4(5)-vinylimidazole, copoly[vinylamine/4(5)-vinylimidazole], and poly(ethylenimine-g L-histidine). All of these catalysts share the common property of water solubility and the capability of attaining high catalytic efficiencies which is attributed to apolar interactions. 

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