Template polymer complex

A template polymer complex, which incorporates N-benzyl-D-valine with almost 100 % stereospecificity, has been synthesized by copolymerization of A-P2-[Co (R,R )-A, /V -bis(4-(vinylbenzyloxy)salicylidene]-l,2-diaminocyclohexane -(A-benzyl-D-valine)], styrene, and divinylbenzene, followed by dissociation of the coordinated amino acid 115). 

The authors found that the yield of 30-mer (a product with 5—6 linkages) was not much smaller than that of 10-mer or 12-mer. These facts indicate that the stability of the complex between the oligonucleotides and the complementary template is the most important factor in determining the extent of the condensation. The strong influences of template polymer (Poly C) are demonstrated in Fig. 9, in which the elution profile is shown of the polymerization products of (2 MeIp)6 in the presence of Poly C (B) and in their absence (A). 

The 1 2 complex of Hg2+ with the tacn derivative mono-N-(4-vinylbenzyl)-l,4,7-triazacyclono-nane copolymerizes with p-divinylbenzene to give an Hg-templated polymer which, after deme-talation with 6N HC1, is a highly selective gathering material for Hg2+ in competition with other transition metals like Cd2+, Ag+, Pb2+, Cu, and Fe3+ at low pH values.211... 

Lubke C, Lubke M, Whitcombe MJ, Vulfson EN. Imprinted polymers prepared with stoichiometric template-monomer complexes efficient binding of ampiciUin from aqueous solutions. Macromolecules 2000 1433 5098-5105. 

The polycomplex obtained by template polymerization of polyacrylamide with uracil groups onto template, from polyacrylamide with adenine groups, was found to be very stable compared with the polymer complex which was formed by mixing both polymers... 

Many polymer-polymer complexes can be obtained by template polymerization. Applications of polyelectrolyte complexes are in membranes, battery separators, biomedical materials, etc. It can be predicted that the potential application of template polymerization products is in obtaining membranes with a better ordered structure than it is possible to obtain by mixing the components. The examples of such membranes from crosslinked polyCethylene glycol) and polyCacrylic acid) were described by Nishi and Kotaka. The membranes can be used as so-called chemical valves for medical applications. The membranes are permeable or impermeable for bioactive substances, depending on pH. 

If a product of template polymerization is composed of a daughter polymer and a template involved in polymer complex, the first step of analysis is separation of these two parts. Separation of two polymers forming a complex is sometimes difficult and depends on interactions between the components. Very often polymeric complexes are insoluble in water and also in organic solvents. In order to dissolve such compounds, aqueous or non-aqueous solutions of inorganic salts such as LiBr, LiCl, NH4CNS are used. Dimethylformamide or dimethylacetamide are commonly used as non-aqueous solvents. If one of the components is a polyacid, alkali solutions are used as solvent. Ferguson and Shah reported that the complex obtained by polymerization of acrylic acid in... 

First a complex is prepared between a polymer ligand, eg. PVP,and a metal ion(M,) and a crosslinking agent is added to the solution of the polymer complex. The metal ion M( is (hen removed by treating the resin with an acid. If the conformation of the polymer-ligand chains in this resin remains the best for the metal ion Mj, used as the template, then the resin should preferentially form complexes with the metal ion M j when dipped into a solution containing various metal ions. 

The pre-polymerization solution was analysed by measuring the absorbance of the template and monomers separately. These results were compared to the resulting spectra of a solution containing both the monomer and template. In another example [32] this approach has been used to confirm the interactions between MAA and 4-L-phenylalanylamino-pyridine. A UV-vis spectroscopy study has shown the increase in absorbance of the band corresponding to the template Umax - 245 nm) upon increasing concentration of the functional monomer. The data were also used as an indication of the formation of a 1 2 template monomer complex. The final polymer obtained was highly enantioselective. 

This first case is the least interesting, although it is by far the most common result in putative template reactions, even when the metal ion is apparently the right size for the desired product A good example is found in the reaction presented in Fig. 6-29. All of the dipositive first-row transition metal ions have similar sizes, but only nickel(n) is effective for the formation of complexes of 6.30 in a template condensation. The other metals either give polymers, complexes of 6.31, or in the case of cobalt(n), compounds that are halfway to the desired product containing 6.32. 

It has been attempted to perform template polymer syntheses without using biological sources. Concepts focus on the formation of a complex between monomer molecules and a present macromolecule [4,480], This way the monomer will get preorganized and the polymerization is supposed to follow a zip mechanism controlled by the length and the configuration of the template polymer, offering replication of the molecular weight and control of the stereo structure. Polymerization of acrylic acid in the presence of poly(ethyleneimine), N-vinylimidazole/ poly(methacrylic acid) or acrylonitrile with poly(vinylacetate) have been described [469,470,471,472,473]. Recently the preparation of solid polyelectrolyte complexes from chitosan and sodium-styrenesulfonate has been reported [481]. 

The first example for Method 2 was reported by Nishide and co-workers, who polymerised a metal complex of 1-vinylimidazole with l-vinyl-2-pyrollidone and divinylbenzene [8]. The metal-vinylimidazole complex was copolymerised, cross-linked with l-vinyl-2-pyrollidone by y-ray irradiation and the template metal ion was removed by treating the polymer complex with an acid. These poly(vinyl-imidazole) (PVI) resins adsorbed metal ions more effectively than the PVI resin prepared without the template. The number of adsorption sites and the stability constant of the Ni(II) complex were larger for the PVI resin prepared with the Ni(II) template, as seen by the smaller dissociation rate constant of Ni(II) from the resin. 

The template, the functional monomers and the cross-linking monomers are dissolved in a non-polar solvent. The functional monomers and the template form complexes and the strength of these are reflected in the selectivity of the imprinted polymer. The choice of functional monomer is based on the template structure. Functional monomers are chosen for their ability to interact non-covalently with the template molecule. The most frequently used functional monomer so far is methacrylic acid (MAA). Also vinylpyridines have been frequently used. As cross-linking monomers, ethyleneglycol dimethacrylate (EDMA) or trimethylolpropane trimethacrylate (TRIM) are widely used. Several other types of functional and cross-linking monomers have been used in molecular imprinting experiments using the non-covalent approach. The choice of monomers is of course important to the... 

Chen H, Olmstead MM, Albright RL, Devenyi J, Fish RH (1997) Metal-ion-templated polymers Synthesis and structure of N-(4-vinylbenzyl)- l,4,7-triazacyclononanezinc(II) complexes, their copolymeiization with divinylbenzene, and metal-ion selectivity studies of the demetalated resins - evidence for a sandwich complex in the polymer matrix. Angew Chem Int Ed Engl 36 642... 

Scheme 1 Generalized depiction ofthe molecular imprinting technique 1—monomers a, b, and c form an attachment to complementary sites on the template. 2—The preassembled template-monomer complex is polymerized with a large excess of crosslinker. 3—The rigid polymer formed in this process retains an arrangement of functional elements complementary both in shape and spatial orientation to the template. 4—Removal of the template reveals a binding pocket or cavity, which can be used to recapture the template species.

Whereas the non templated polymer gives a selectivity of 33% e.e. (.S)-phenyl-ethanol, the imprinted-polymerised [bis-((R,R)-diamine l)-l-(iS)-phenylethoxy-rhodium] complex allows an increase of 10% e.e in imprinted alcohol. The utilisation of [bis-((R,R)-diamine l)-l-(/ )-phenylethoxy-rhodium] complex shows a slight decrease of e.e.. These results may represent an imprinting effect. 

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