Poly vinylimidazole Derivatives

The metalloporphyrin complexes and their derivatives have been studied from the standpoint of model compounds of hemoglobin. The polymer-metalloporphyrin complexes are also formed by the reaction in Scheme 8, and a few qualitative investigations have been made with poly(L-lysine)9,10, poly(L-histidine)11, and poly(vinylimidazole)12 as the polymer ligand. Blauer9 has studied the complex formation of heme with poly(L-lysine) and has discussed the effects of the molecular weight and secondary structure of poly(L-lysine) on complex formation. 

IM-COOH-OH cooperation. Polymers such as poly(4(5)-vinylimidazole-co-7-vinyl-7-butyrolactone), poly(IM-la), and poly(4(5)-vinylimidazole-co-acrylic acid-covinyl alcohol) derived from poly(4(5)-vinylimidazole-co-methyl acrylate-co-vinyl acetate), both of which contain imidazole, carboxylic acid and hydroxyl moieties are synthesized and studied as a model of a-chymotrypsin (29). The former has a relatively ordered sequence and the latter has a random one. Results are tabulated in Table 11. The polymers cited in the Tabel contain a similarly low quantity of imidazole moiety, so that the cooperation of two subsequent imidazole moieties need not be discussed. Polymers such as L-84, L-68, M-83 and A-84 have higher catalytic activities than the polymer V-82. This suggests that the catalytic activity of the imidazole moiety in the polymers is much promoted by the carboxylate moiety in the polymers. The catalytic activities of L-84 and L-68 which have an ordered sequence are more than twice as high as that of M-83, having a random sequence. From these results it is concluded that the introduction of the hydroxyl moiety which has little cooperative effect on the imidazole moiety in V-82 in this reaction conrfition into imidazole and carboxylate — containing polymer, increases... 

The significance of the coulombic field is observed (79). Figure 9 shows the catalytic activities of poly(4(5)-vinylimidazole-co-acrylic acid), poly(IM-ac), and low molecular weight imidazole derivatives in hydrolyses of various substituted phenyl acetates of which leaving groups have different activities. 

Polycarbobetaines derived from aromatic or heteroaromatic systems are listed in Scheme 3. The vinylimidazolium betaines 13 and 14 were prepared by alkylation of 1-vinyhmidazole with the corresponding bromocarboxylic acid, and aqueous solution polymerization using an azo initiator [29]. Polymers 13b, 15, 16, and 17b were made by the addition of acryUc or propiolic acid to poly(4-vinylpyridine) and poly(N-vinylimidazole). Kinetic measurements revealed a mechanism consisting of two reactions first, addition of two molecules of acid to the polymer second, the formation of an equilibrium between the adduct and the betaine structure [30,31]. 

Hydrophobic domains are created on synthetic polymers by attaching apolar groups to the polymer backbones. Polymers such as the IV-alkylated forms of poly(4-vinylpyridine) and poly(A -vinylimidazole), or the Af-alkylated or N-acylated derivatives of PEI contain both hydrophobic groups and charged centers... 

Two older reviews summarize work in this field [124,125]. The following derivatives have been employed as porphyrins Fe(II,III) protoporphyrin-EX (heme, hemin), Fe(II,III) or Co(II) protoporphyrin-IX-diester, chlorophyllins with different metal ions in the core, Fe(II) tetraphenylporphyrin, Mg(II) or Fe(II,III) octaethylporphyrin, Fe(II,III) tetrakis[o-(alkylamido)phenyl]-porphyrin. Polymers with N-donor groups are based on proteins such as poly(L-lysine), poly(L-histidine), poly(Y-benzyl-L-glutamate) or synthetic polymers such as homopolymers and copolymers with vinylpyridine, iV-vinylimidazole or ethyleneimine. 

Water soluble, hydrophobic terpolymers of 4(5)-vinylimidazole were prepared in order to investigate hydrophobic effects attributed to random, covalently bound pendant apolar side chains in the hydrolysis of the charged apolar ester substrates (S ). The rationale for the preparation of these terpolymers is provided in the analogy to the poly[4(5)-vinylimidazole] catalysts. The apolar nature of the catalyst poly[4(5)-vinylimidazole] is derived from its hydrocarbon backbone and formation of the transient and hydrophobic N-acylimidazole intermediate. Accumulation of long-chain acylated imidazole residues, which increases hydrolysis rates dramatically, inspired the concept of utilizing hydrophobic polymer side chains. 

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