Molecular templating

In a further study, Rill et al. [325] developed a model of gel permeation chromatography that included a bimodal pore stracture. The smallest mode in the pore-size distribution represents the basic background polyacrylamide pore structure of about 1-mn mean radius, and the second mode was around 5 nm, i.e., in the range of size of the molecular templates. The introduction of this second pore structure was found to substantially improve the peak resolution for molecules with molecular sizes in the range of the pore size. 

The use of ordered supramolecular assemblies, such as micelles, monolayers, vesicles, inverted micelles, and lyotropic liquid crystalline systems, allows for the controlled nucleation of inorganic materials on molecular templates with well-defined structure and surface chemistry. Poly(propyleneimine) dendrimers modified with long aliphatic chains are a new class of amphiphiles which display a variety of aggregation states due to their conformational flexibility [38]. In the presence of octadecylamine, poly(propyleneimine) dendrimers modified with long alkyl chains self-assemble to form remarkably rigid and well-defined aggregates. When the aggregate dispersion was injected into a supersaturated... 

Choi S-J, Woo D-H, Myung N, Kang H, Park S-M (2001) Electrochemical preparation of cadmium selenide nanoparticles by the use of molecular templates. J Electrochem Soc 148 C569-C573... 

Spreader-Bar Structures as Molecular Templates for Electrochemical Synthesis of Nanoparticles... 

Thermodynamic control (Figure 1, right) is based on adsorption of substances until quasi-equilibrium stage. In this case, the surface ratio of the adsorbed species is defined by the ratio of products of their concentration and binding constant. This deposition is much less influenced by poorly controllable fluctuations of external conditions and provides much better reproducibility. The total coverage can be almost 100%. Because of these reasons, the thermodynamic control is advantageous for preparation of mixed nanostructured monolayers for electrochemical applications including a formation of spreader-bar structures for their application as molecular templates for synthesis of nanoparticles. 

Steinke,., Sherrington, D. C. and Dunkin, I. R. Imprinting of Synthetic Polymers Using Molecular Templates. Vol. 123, pp. 81-126. 

Kidambi, S., Chan, C., and Lee, I. (2004) Selective depositions on polyelectrolyte multilayers Self-assembled monolayers of m-dPEG acid as molecular template./. Am. Chem. Soc. 126, 4697-4703. 

FIGURE 1.49 Principle of molecular imprinting.169 1 = functional monomers 2 = cross-linking monomer 3 = molecule whose imprint is desired (molecular template). In (A), 1 and 2 form a complex with 3 and hold it in position in (B), polymerization involving 1 2 occurs and the template (imprint molecule) is held in the polymeric structure in (C) and (D) the imprint molecule is removed leaving a cavity complementary to its size and shape into which a target analyte of similar dimensions can fit. (Reproduced with permission from Taylor Francis.)... 

Islam, S. A., Wolf, C. R., Lennard, M. S., and Sternberg, M. J. (1991) A three-dimensional molecular template for substrates of human cytochrome P450 involved in debrisoquine 4-hydroxylation. Carcinogenesis 12, 2211-2219. 

Wulff G. Molecular imprinting in cross-linked materials with the aid of molecular templates— a way towards artificial antibodies. Angew Chem Int Ed Engl 1995 34 1812-1832. 

The electrochemical preparation of CdSe nanoparticles at gold electrodes modified with molecular templates was reported [159]. The molecular templates were obtained by arranging thiolated... 

Molecular descriptors vary gready in both their origins and their applications. They come from both experimental measurements and theoretical computations. Typical molecular descriptors from experimental measurements include logP, aqueous solubility, molar refractivity, dipole moment, polarizability, Hammett substituent constants, and other empirical physicochemical properties. Notice that the majority of experimental descriptors are for entire molecules and come directly from experimental measurements. A few of them, such as various substituent constants, are for molecular fragments attached to certain molecular templates and they are derived from experimental results. 

I. Designing specifications for the target and the molecular templates (scaffold)... 

The fabrication of regular arrays of metallic nanoparticles by molecular templating is of great interest in order to prepare nanometre structures for future use in nanoelectronics, optical and chemical devices.43 A sensitive, rapid and powerful direct analytical method is required for the quantitative analysis of high purity platinum or palladium nanoclusters produced by biomolecular... 

Transition-state stabilization The active site often acts as a flexible molecular template that binds the substrate in a geometric structure resembling the activated transition state of the molecule (see T at the top of the curve in Figure 5.4). By stabilizing the substrate in its transition state, the enzyme greatly increases the concentration of the reactive intermediate that can be converted to product and, thus, accelerates the reaction. 

Fig. 1 General principle of molecular imprinting. A molecular template (T) is mixed with functional monomers (M) and a cross-linker (CL) resulting in the formation of a self-assembled complex (1). The polymerization of the resulting system produces a rigid structure bearing imprinted sites (2). Finally removal of the template liberates cavities that can specifically recognize and bind the target molecule (3). Adapted with permission from [3]. Copyright 2003 American Chemical Society...

Fig. 4 Chemical structures of molecular templates for which MIPs were synthesized in mixed organic/aqueous solvents...

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