Via ionic interactions

Smith P. and Eisenberg A., lonomeric blends. I. Compatibilization of the polystyrene-poly(ethyl acrylate) system via ionic interactions, J. Polym. Sci., Polym Lett., 21, 223, 1983. 

One of the only examples of a commercial process using immobilised homogeneous catalysts comprises an anionic rhodium complex [RhI2(CO)2] that is bound via ionic interactions to an ion exchange resin [3] and is used for the carbonylation of methanol. 

The most common methods used to determine protein concentration are the dye-binding procedure using Coomassie brilliant blue, and the bicinchonic-acid-based procedure. Various dyes are known to bind quantitatively to proteins, resulting in an alteration of the characteristic absorption spectrum of the dye. Coomassie brilliant blue G-250, for example, becomes protonated when dissolved in phosphoric acid, and has an absorbance maximum at 450 nm. Binding of the dye to a protein (via ionic interactions) results in a shift in the dye s absorbance spectrum, with a new major peak (at 595 nm) being observed. Quantification of proteins in this case can thus be undertaken by measuring absorbance at 595 nm. The method is sensitive, easy and rapid to undertake. Also, it exhibits little quantitative variation between different proteins. 

Noncovaient Anchoring of Organometallic Complexes via Ionic Interactions... 

A further few ionic compounds based on unsupported heterometallic interactions between metal centers from the anion and the cation were reported only recently [604—606]. Thus, treatment of [Ag(Tab)2](PF6) with K[Au(CN)2] generated the complex [ (Tab)2Ag Au(CN)2 ]2 446 [605]. In the solid state [Ag(Tab)2]+ cations and [Au(CN)2] anions are held together via ionic interactions [Au-Ag 2.9598(7)/2.9185... 

Fig.10 Polyoxometallate clusters anchored to soluble support via ionic interactions...

A sustained drug release is favourable for drugs with short elimination half-life. It can be controlled by hydration and diffusion mechanisms or ionic interactions between the drug and the polymeric carrier. In the case of diffusion control the stability of the carrier system is essential, as its disintegration leads to a burst release. Therefore, the cohesiveness of the polymer network plays a crucial role in order to control the release over several hours. Due to the formation of disulphide bonds within the network thiomers offer adequate cohesive stability. Almost zero-order release kinetics could be shown for insulin embedded in thiolated polycarbophil matrices (Clausen and Bernkop-Schnurch 2001). In the case of peptide and protein drugs release can be controlled via ionic interactions. An anionic or cationic polymer has to be chosen depending... 

Tetracycline has been shown to bind to gastrointestinal mucus by hydrogen-bonding and via electrostatic and hydrophobic interactions. It has been suggested that cephaloridine and gentamicin bind intestinal mucin via ionic interactions. In addition, gentamicin has been shown to bind to sputum and tobramycin binds to glycoprotein- and DNA-rich fractions of sputum. 

Fig. 20. Schematic diagram describing the end-tethered nanocomposites. The layered silicates are highly anisotropic with a thickness of lnm and lateral dimensions (length and width) ranging from -100 nm to a few microns. The polymer chains are tethered to the surface via ionic interactions between the silicate layer and the polymer-end. Adapted from Ref. [54].

Another approach towards immobilization via ionic interactions is the use of tethered metal ions, such as Cu, Co, or Ni, in order to bind the enzyme [53, 54]. This is particularly so when the enzyme contains an easily accessible imidazole residue from histidine [55] or a His tag (Figure 2.6) [56-59], that is a short tag with six histidines. This tag can be readily introduced by genetically modifying the enzyme. Little influence of the tag on the catalytic performance has been noticed. When benzaldehyde lyase [60] was immobilized on an Ni -containing polyvinylpyrrolidinone-based matrix, it could be reused several times for the formation of benzoin (12) (Scheme 2.4) [58]. 

The explanation offered by the authors is that the MIP was cross-reactive for naphthalene sulfonates. However, at pH 2.3, only the naphthalene sulfonates were anionic (pfCa 0.5-0.6). It is quite plausible that in this example, molecular recognition was predominantly an anion-exchange mechanism, and that this overshadowed the influence of any molecularly imprinted cavities. In this way, the MeOH wash step could be seen to have disrupted non-covalent, non-ionic interactions, leaving behind the anionic naphthalene sulfonates, which were retained much more strongly via ionic interactions with the protonated pyridyl moieties. Unfortunately, this is always a poten-... 

Previously, Hogen-Esch reported the successful synthesis of block copolymers composed of poly(acetylene) (PA) segments (PS-b-PA), by the living anionic block copolymerization of styrene and phenyl vinyl sulfoxide, followed by thermal treatment [158]. In this way, poly(phenyl vinyl sulfoxide) was completely converted to a PA segment A similar block copolymer was obtained by the reaction of chain-end-amine-fimctionaHzed poly(4-methylphenyl vinyl sulfoxide) with chain-end-COOH-functionaHzed PS via ionic interaction, followed by thermal treatment [215]. 

This is the so-called silanophilic activity of the reversed phase. The compounds affine to silanol-groups are usually bases that interact with the acidic silanol groups via ionic interactions. These interactions are energetically much stronger than the usual hydrophobic interactions of reversed phases, which usually lead to wider elution bands for basic analytes on classical reversed phases. 

Catalysts Supported via Ionic Interactions There have been a number of reported Ru catalysts modified with ionic groups for use in ionic liquids (ILs) or other reaction media (see Section 5.3). The overall goal of these strategies was aimed toward... 

Molecular Composites via Ionic Interactions and Their Deformation—Fracture Properties... 

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