4-vinylphenylboronic acid ester

Fig. 2-2 Covalent imprinting of mannopyranoside using its 4-vinylphenylboronic acid ester as a functional monomer...

Scheme 15.2 Covalent imprinting of a-phenyl-D-mannopyranoside in a divinyl benzene/4-vinylphenylboronic acid matrix, via the formation of covalent boionic ester linkages between the 4-vinylphenylboronic acid and the carbohydrate. Adapted from Wulff, Vesper, et al. (1977). Copyright 1977 Wiley InterScience.

Covalent interactions (Fig. 7) this approach involves the formation of an easily cleavable functionalised monomer-template complex [61, 18]. The first example of an imprinted polymer network was prepared by Wulff s group and used the reversible formation of an ester bond between a diol and 4-vinylphenylboronic acid [15]. The reaction rates to reach equilibrium between the ester and boronic acid are comparable to those obtained with... 

By removing water under a reduced pressure at 40 °C, the ester of 4-vinylphenylboronic acid (0.30 g, 2.0 mmol) and sialic acid (0.62 g, 2.0 mmol) were prepared in dry pyridine (200 mL). The product was directly used for the polymerization (the covalent conjugate did not have to be isolated, since its formation was almost quantitative). This ester, ethylene glycol dimethacrylate (5.6 g, 28.2 mmol) and ADVN were dissolved in DMF (3.2 mL), and the polymerization was initiated by irradiating with UV light at 4 °C. After 12 h, the polymer was ground, and treated with 1 1 mixture of 0.01 M hydrochloric acid and methanol. By this post-treatment, the boronic acid esters were hydrolyzed and the sialic acids were removed from the polymer [2],... 

It was investigated whether non-covalent interactions between the template and added comonomers were strong enough during polymerization to allow the formation of specific structures within the cavities. In the case of D-glyceric acid-2,3-0-(4-vinylphenylboronate) an additional weak electrostatTc interaction was used by polymerization in the presence of an equimolar amount of 2-vinyl-pyridine ( ). By this procedure the selectivity was enhanced. On the other hand, a strong additional electrostatic interaction decreased selectivity (32,55). An additional charge transfer interaction also improved the selectivity as can be seen from Table IV. Here, an electron deficient ester moiety (4-nitrobenzyl-) was polymerized in the presence of N,N-dimethylaminostyrene. 

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