Solution interactions with cations

When a nucleic acid interacts with cations in aqueous solution, bound states form in the interfacial region of the macromolecule [10], These states are classified either as site bound or diffusely bound [9, 11-14], If the translational energy of the ions is unable to overcome the electrostatic forces between the ions and the nucleic acid, then the ions are viewed as trapped in a volume encasing the surface of the nucleic acid. These ions are site bound [9, 11, 13, 14]. 

Henry B, Desvaux H, Pristchepa M, Berthault P, Zhang YM, Mallet JM, Esnault J, Sinay P. NMR smdy of a Lewis pentasaccharide 42. derivative Solution structure and interaction with cations. Carbo-... 

Figures 3 and 4 show Kd values observed for two macroporous cation exchange resins, Duolite GT-73 and Amberlite IRC-718. The adsorption of plutonium on both resins was relatively weak compared with other adsorbents, especially at the lower initial plutonium concentrations. At initial concentrations of about 1 pCi/L, Kd values for Duolite GT-73 and Amberlite IRC-718 were approximately 200 and 76 ml/g, respectively. Surprisingly, no dependence on pH is apparent at the lower initial plutonium concentrations. More cationic plutonium species should be present at lower pH values and would be more strongly adsorbed on cation exchange resin. This effect is only observed for Duolite GT-73 at the higher initial plutonium concentration, 10 iCi/L. The absence of a pH effect at the lower concentration can be explained by the existence of a small concentration of a stable plutonium species in solution that does not interact with cation resins. Additional evidence supporting this explanation is the fact that about 1.3 to 2.8% of the initial plutonium is not adsorbed on the cation resins in both the batch equilibrium adsorption measurements and the column adsorption experiments discussed later. This small fraction of plutonium is not adsorbed over a...

The variation of the natural organics characteristics with changes in solution chemistry, their interaction with cations and other compounds and their interactions with inorganic colloids will also be discussed. These interactions occur in natural waters and may also influence treatability. A brief description of colloid characterisation and aggregation mechanisms is also given. 

The electron transfer activity of the quinone/hydroquinone pair has often been described through radical reactions [40] the carbonyl groups can stabilize the created radicals that may accept electrons and become anions, which can transfer electron back and become radicals or can interact with cations in solution. Then, reversible proton transfer leads to phenolic hydroquinone sites ... 

The Effect of Degree of Polymerization of Silicates on Their Interactions with Cations in Solution... 

Falcone, Jr. J.S. The Effect of Degree of Polymerization of Siheates on Their Interactions with Cations in Solution , in Soluble Silicates, Falcone, J.S., Ed. (1982) ACS Books Washington, DC. 

In many cases broad, asymmetric peaks are observed that can be indicative of solute interactions with the capillary wall. If cationic analytes are involved, this behavior is to be expected, since at pH 4.0, silanols are deprotonated and will attract cationic species (e.g., basic residues of peptide side chains). 

The addition of cationic surfactant to an anionic polysaccharide solution shows its greatest effect near the surfactant cmc. As the surfactant concentration increases beyond the cmc, the polysaccharide may go back into solution or it may form an insoluble complex, flocculate, and settle out of solution. In general, as the polysaccharide s anionic charge increases, so does its interaction with cationic surfactants. As an example, alginic acid binds more strongly to cationic surfactants than carboxymethylcellulose. 

The possibilities of coordinatively unsaturated sites in the stracture of MOFs allows for unique detection of both Lewis acids and bases. Unsaturation of coordinating ligands allows for possible interactions with cations that may reversibly enter the framework. Cations typically exist in the framework stmcture of MOFs, and cation exchange may occur readily under appropriate conditions. Such interactions can have dramatic effects on the luminescent properties of MOFs and allows for unique sensing applications involving various cations in solution. 

The anion series in the order of their influence on the surface activity of cationic surfactants and on the properties of insoluble monolayers coincide with the lyotropic series. The anion nature is manifested in the specific interaction with cationic surfactants with the formation of ionic pairs or in the anion penetration into the adsorption monolayers. Apparently, charge transfer complexes are frequently formed at the water-air and water-oil interfaces between the adsorbed cations and anions. Mukerjee and Ray estabhshed that these complexes exist in ionic pairs, between Br or J anions and dodecylpyridine ions in chloroform, and also on the micelle surface formed by the same cations in water [84-86]. The data on the ionic pair structure at the interface can be obtained by spectral study of monolayers and solutions of ionogenic surfactants in nonpolar solvents. According to Goddard, the investigation on the mixed monolayers formed by the surface-active anions and quaternary ammonium compounds will enable us to better understand the specific properties of the interaction between the adsorbed ions [72]. 

An ion-exchange membrane that interacts with cations and have a variety of anion functional groups affixed to the membrane (—COO , —SO, —POj , —C6H40 , etc). These functionalities allow cations to pass through the membrane and prevents anions from passing through the membrane. The ability of the membrane to bind ions is greatly dependant on the pH of the solution and the ions of interest. 

Campbel-Falcone. The effect of degree of polymerization of silicates on their interactions with cations in solution. ACS Symposium, 1982, Vol. 194. 

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