Imprinting, substrate

The author s own interest in this area includes new functional polymers for solid phase synthesis [11-13], polymers with molecularly imprinted substrate selectivity [14], polymer-supported transition metal catalysts [15], novel polymers of potential interest for electrocatalysis [16], targeting of colloidal drug carriers [17, 18], molecular composites [19], and biocompatible surfaces [20]. These studies have led to, among other things, a uniquely versatile method of polymer synthesis based on the chemistry of activated acrylates, i.e. polymer synthesis via activated esters. Various aspects of polymers and copolymers of activated (meth)acrylates have also been investigated in this and several other laboratories. 

It is conventional to put the higher value in the numerator (which is usually the imprinted substrate) and the lower value in the denominator. The specific selectivity factor indicates how many times more the imprinting effect is observed for substrate 1 vs. substrate 2 on one polymer. Thus, the specific selectivity factor does not take into account partitioning effects between two molecules due to nonimprinted effects. For enantiomeric compounds, the value for is the same for both substrates, thus the specific selectivity factor simply reduces to a. 

M. Bcrggren, A. Dodabalapur, R. E. Slusher, Organic solid-state lasers with imprinted gratings on plastic substrates, Appl. Phys. Leu. 1998, 72, 410. 

Fig. 1. Preparation of configurational biomimetic imprinted networks for molecular recognition of biological substrates. A Solution mixture of template, functional monomer(s) (triangles and circles), crosslinking monomer, solvent, and initiator (I). B The prepolymerization complex is formed via covalent or noncovalent chemistry. C The formation of the network. D Wash step where original template is removed. E Rebinding of template. F In less crosslinked systems, movement of the macromolecular chains will produce areas of differing affinity and specificity (filled molecule is isomer of template).

The concept of thin films of a molecularly imprinted sol-gel polymer with specific binding sites for a target analyte is general and can be applied also to electrochemical sensors. For example, a sensor to detect parathion in aqueous solutions is based on films cast on glass substrates and on glassy carbon electrodes (Figure 6.14).12... 

Fig. 14. Application of an AT-benzylisopropylamine imprinted MAA/EGDMA copolymer as catalyst for the dehydrofluorination of 4-fluoro-4-(p-nitrophenyl)-2-butanone in a batch reactor. Given is the substrate concentration versus time. The reaction was carried out at 50° C in 10 ml of a mixture of water and acetonitrile 1 1 (v/v), containing 5 mg of the substrate 4-fluoro-4-(p-nitrophenyl)-2-butanone (i. e., a final concentration of 2.4 mmol/1) and 500 mg MIP or non-im-printed control polymer (CP). Top use of MIP, 1. experiment ( ), 2. experiment ( ). Bottom use of CP, 1. experiment ( ), 2. experiment ( ). Reprinted with permission from Briiggemann O (2001) Anal Chim Acta 435 197. Copyright 2001 Elsevier Science...

Silica particles surface-imprinted with a TSA of a-chymotrypsin were applied for the enantio-selective hydrolyzation of amides. Surprisingly, the particles showed reverse enantio-selectivity, i. e., the sol-gel imprinted with the L-isomer of the enzyme s TSA showed a higher selectivity for the D-isomer of the substrate [125]. Also Ti02 gels have been imprinted, e.g., with 4-(4-propyloxypheny-lazo)benzoic acid. QCM coated with ultrathin films of this gel were prepared by an immersion process and showed selective binding of the template [ 126]. These examples demonstrate once more the broad applicability of the concept of molecular imprinting. 

Wang, Q.H.,etal., Understanding and controlling the substrate effect on graphene electron-transfer chemistry via reactivity imprint lithography. Nature Chemistry, 2012. 4(9) p. 724-732. 

Nickel AML, Seker E, Ziemer BP, Ellis AB. Imprinted poly (acrylic acid) films on cadmium selenide. A composite sensor structure that couples selective amine binding with semiconductor substrate photoluminescence. Chem Mater 2001 13 1391-1397. 

Sellergren B, Andersson L. Molecular recognition in macroporous pol3miers prepared by a substrate-analog imprinting strategy. J Org Chem 1990 55 3381-3383. 

Sellergren B, Lespisto M, Mosbach K. Highly enantioselective and substrate-selective polymers obtained by molecular imprinting utilizing noncovalent interactions. NMR and chromatographic studies on the nature of recognition. J Am Chem Soc 1988 110 5853-5860. 

Molecularly imprinted polymer (MIP) films can be utilized in conjunction with CdSe PL changes to enhance the selectivity of the sensor. MIPs have been developed to mimic the selective binding of molecules to biological substrates, as in... 

Of special interest is the eventuality of stabilizing transition states by imprinting their features into cavities or adsorption sites using stable transition state analogs as templates. Studies towards such TSA footprint catalysis have been performed by generating TSA complementary sites as marks on the surface [7.73a] or as cavities in the bulk [7.73b] of silica gel. These imprinted catalytic sites showed pronounced substrate specificity [7.74a,b] (namely in the case of cavities [7.73 b]) and chiral selectivity [7.74c,d]. 

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