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Non-covalent linkers

Helicates are formed in cooperative metal-directed self-assembly processes, usually from linear ligand strands possessing several metal coordination sites and appropriate numbers of metal ions (Scheme 2.1, top). As an alternative, helicates are obtained in a hierarchical process by initial formation of mononuclear complexes connected by non-covalent linkers (e.g., metal ions) in a subsequent step. Thus, in the... [Pg.19]

Ito, Y, Hosomi, H., and Ohba, S., Compelled orientational control of the solid-state photodimerization of frans-cinnamamides dicarboxylic acid as a non-covalent linker. Tetrahedron, 56, 6833, 2000. [Pg.428]

Recent developments in DNA/RNA chemical synthesis have allowed us to attach some functional groups covalently to nucleic acids, thus permitting the introduction of a functionality or properties not normally present in the native biomolecule The use of non-nucleosidic linkers is probably the most popular approach for the 5 -terminal modification of chemically synthesized nucleic acid oligonucleotides and a number of such linkers are commercially available. The linker shown in Fig. 2 is designed as a phosphoramidate derivative so that it can be incorporated into the 5 -terminus of the sequence as the last... [Pg.520]

Fig. 16.1 Sodium channel structure. Schematic representation of the sodium channel subunits, a, ySl and / 2. (A) The a-subunit consists of four homologous intracelIularly linked domains (I—IV) each consisting of six connected segments (1-6). The segment 4 of each of the domains acts as the voltage sensor, physically moving out in response to depolarization resulting in activation of the sodium channel. The channel is inactivated rapidly by the linker region between III and IV docking on to the acceptor site formed by the cytoplasmic ends of S5 and S6 of domain IV. The / -subunits have a common structure, with the / 1 non-covalently bound, and f 2 linked by disulfide bonds to the a-channel... Fig. 16.1 Sodium channel structure. Schematic representation of the sodium channel subunits, a, ySl and / 2. (A) The a-subunit consists of four homologous intracelIularly linked domains (I—IV) each consisting of six connected segments (1-6). The segment 4 of each of the domains acts as the voltage sensor, physically moving out in response to depolarization resulting in activation of the sodium channel. The channel is inactivated rapidly by the linker region between III and IV docking on to the acceptor site formed by the cytoplasmic ends of S5 and S6 of domain IV. The / -subunits have a common structure, with the / 1 non-covalently bound, and f 2 linked by disulfide bonds to the a-channel...
Fig. 1. Concept of molecular imprinting - the non-covalent approach. 1. Self-assembly of template with functional monomers. 2. Polymerization in the presence of a cross-linker. 3. Extraction of the template from the imprinted polymer network. 4. Selective recognition of the template molecule... Fig. 1. Concept of molecular imprinting - the non-covalent approach. 1. Self-assembly of template with functional monomers. 2. Polymerization in the presence of a cross-linker. 3. Extraction of the template from the imprinted polymer network. 4. Selective recognition of the template molecule...
Gd(III) chelates, the relatively low relaxivity is the consequence of the flexibility of the linker group between the Gd(III) chelate and the rigid dendrimer molecule (slow water exchange is also limitative). Internal flexibility has been also proved for certain non-covalently bound Gd(III) chelate - protein adducts. The tr value determined for MP-2269 bound to bovine serum albumin is 1.0 ns, one order of magnitude lower than the rotational correlation time of the protein molecule [50]. [Pg.82]

Conventionally, MlPs are obtained by bulk co-polymerization from a mixture consisting of a functional monomer, cross-linker, chiral template, and a porogenic solvent mixture. Nowadays, imprinting via non-covalent template binding is preferred over the covalent mode and involves three major steps (see Fig. 9.9). (i) Functional monomers (e.g. methacrylic acid, MAA) and a cross-linker (e.g. ethyleneglycol dimethacrylate, EDMA) assemble around the enantiomeric print molecule, e.g. (S)-phenylalanine anilide (1), driven by non-covalent intermolecular interactions, e.g. ionic interactions, hydrogen bonding, dipole-dipole interaction. Tr-rt-interaction. (ii) By thermally or photochemi-... [Pg.373]

Fig. 21.14. Sensitivity pattern to xylenes and ambient humidity (rH) of a non-covalent MIP array PMA (MAA and EDMA) and PSt (styrene and divinylbenzene) with 85 and 70% cross-linker. PMA85/PSt85 is p-xylene and PMA70/PSt70 o-xylene imprinted. Data evaluation is shown in Table 21.2. Fig. 21.14. Sensitivity pattern to xylenes and ambient humidity (rH) of a non-covalent MIP array PMA (MAA and EDMA) and PSt (styrene and divinylbenzene) with 85 and 70% cross-linker. PMA85/PSt85 is p-xylene and PMA70/PSt70 o-xylene imprinted. Data evaluation is shown in Table 21.2.
An example of a non-covalent MIP sensor array is shown in Fig. 21.14. Xylene imprinted poly(styrenes) (PSt) and poly(methacrylates) (PMA) with 70 and 85% cross-linker have been used for the detection of o- and p-xylene. The detection has been performed in the presence of 20-60% relative humidity to simulate environmental conditions. In contrast to the calixarene/urethane layers mentioned before, p-xylene imprinted PSts still show a better sensitivity to o-xylene. The inversion of the xylene sensitivities can be gathered with PMAs and higher cross-linker ratios. As a consequence of the humidity, multivariate calibration of the array with partial least squares (PLS) and artificial neural networks (ANN) is performed, The evaluated xylene detection limits are in the lower ppm range (Table 21.2), whereas neural networks with back-propagation training and sigmoid transfer functions provide the most accurate data for o- and p-xylene concentrations as compared to PLS analyses. [Pg.524]

Molecular imprinting technique was recently used to prepare highly selective tailor-made synthetic affinity media used mainly in chromatographic resolution of racemates or artiftcial antibodies [130-133]. A complex between the template molecule and the functional monomer is first formed in solution by covalent or non-covalent interactions (Figure 3.10). Subsequently, the three-dimensional architecture of these complexes is confined by polymerization with a high concentration of cross-linker. The template molecules are then extracted from the polymer leaving behind complementary sites (both in shape and functionahty) to the imprinted molecules. These sites can further rebind other print molecules. [Pg.38]

By using dicarboxylic acids as a non-covalent intermolecular linker, a compelled orientational control of the solid-state [2-1-2] photodimerization of trans-... [Pg.41]


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