Electrostatic affinity

The potential at which the maximum occurs is different for different ions. In light of the third item, the differences in the voltage coordinates of the maxima must reflect differences in the chemical (as opposed to purely electrostatic) affinities of the ions for the interface. Nonionic solutes have also been investigated extensively, but we do not go into this aspect of the subject. 

Snoeren, T. H. M., van der Spek, C. A. and Payens, T.A.J. 1977. Preparation of /(-casein and minor as-caseins by electrostatic affinity chromatography. Biochim. Biophys. Acta 490, 255-259. 

Ion-Exchange Chromatography. Ion exchange is perhaps the most classic and popular type of chromatography used in biochemistry. It relies on the differential electrostatic affinities of molecules car-... 

Although it is logical to discuss points of zero charge in the context of electric double layers, these are typical non-electric surface properties, because they reflect the difference in non-electrostatic affinity of the two charge-determining species for the uncharged surface. So. for oxides the p.z.c. is related to pK and pKjj. the dissociation constants for the acid and base functions of the surface hydroxyl groups. 

Lanthanides have high electrostatic affinity for Ca " " binding sites, most likely due to their shared properties such as ionic size and charge density. Thus, lanthanides could compete for, or displace, Ca " " from... 

Fig. 4 Transfection process of TMC-Cys nanocomplexes (NC) including cell binding through electrostatic affinity and disulfide bonding, uptake via endocytosis, endosomal escape, intracellular plasmid DNA release, and nuclear transport of plasmid DNA [39]...

While there is less intrinsic electrostatic affinity between an anion and a neutral host compared to that between an anion and a cationic receptor, neutral receptors do not automatically come accompanied by a counter-anion and so it has been suggested that they could potentially exhibit greater selectivity as a class of receptors. Of course, we have to remember that if the receptor is neutral then it will not only bind an anion but will also bind its counter-cation. If this aspect is neglected, then the identity and solvation characteristics of the counter-cation can play an important and unpredictable role in the overall host selectivity (Section 2.4.2)... 

In some cases, specifically adsorbed ions (that have non-electrostatic affinity to the surface) enrich the surface but may not be considered as part of the surface, e.g. bivalent cations on oxides, cationic and anionic surfactants on most surfaces [17]. 

A detailed description of how the E and C parameters are determined is presented in the literature [76, 168-170]. The E and C values which best reproduce several hundreds of experimental enthalpy data are summarized in Table 1.18. They are expressed in (kJ mor ) by multiplying the literature values, in (kcal mor ), by V4.184. With diiodine arbitrarily chosen as the reference acid and assigned parameters Ea = 1.02 and Ca = 4.09 (kJ mor ), the Ca and Cb values cannot be compared directly with the Ea and E-q values. However, the relative magnitudes of the Cb (Cb) parameters give an indication of the relative covalent (electrostatic) affinities of the Lewis bases. 

Were we to simply add the ionization energy of sodium (496 kJ/mol) and the electron affin ity of chlorine (—349 kJ/mol) we would conclude that the overall process is endothermic with AH° = +147 kJ/mol The energy liberated by adding an electron to chlorine is msuf ficient to override the energy required to remove an electron from sodium This analysis however fails to consider the force of attraction between the oppositely charged ions Na" and Cl which exceeds 500 kJ/mol and is more than sufficient to make the overall process exothermic Attractive forces between oppositely charged particles are termed electrostatic, or coulombic, attractions and are what we mean by an ionic bond between two atoms... 

Collectors ndFrothers. Collectors play a critical role ia flotation (41). These are heteropolar organic molecules characterized by a polar functional group that has a high affinity for the desired mineral, and a hydrocarbon group, usually a simple 2—18 carbon atom hydrocarbon chain, that imparts hydrophobicity to the minerals surface after the molecule has adsorbed. Most collectors are weak acids or bases or their salts, and are either ionic or neutral. The mode of iateraction between the functional group and the mineral surface may iavolve a chemical reaction, for example, chemisorption, or a physical iateraction such as electrostatic attraction. 

The (I)-(III)-samples sorption ability investigation for cationic dyes microamounts has shown that for DG the maximum rate of extraction is within 70-90 % at pH 3. The isotherm of S-type proves the physical character of solution process and a seeming ionic exchange. Maximal rate of F extraction for all samples was 40-60 % at pH 8 due to electrostatic forces. The anionic dyes have more significant affinity to surface researching Al Oj-samples comparatively with cationic. The forms of obtained soi ption isotherms atpH have mixed character of H,F-type chemosorption mechanism of fonuation of a primary monolayer with the further bilayers formation due to H-bonds and hydrophobic interactions. The different values of pH p for sorbents and dyes confirm their multifunctional character and distinctions in the acid-base properties of adsoi ption centers. 

Ion-exchange chromatography involves an electrostatic process which depends on the relative affinities of various types of ions for an immobilised assembly of ions of opposite charge. The stationary phase is an aqueous buffer with a fixed pH or an aqueous mixture of buffers in which the pH is continuously increased or decreased as the separation may require. This form of liquid chromatography can also be performed at high inlet pressures of liquid with increased column performances. 

Edit Output File icon xlix effective core potentials 101 electron affinity 142 electron correlation 6, 114,118 electron density 165 electron spin 259 electronic structure theory 3 electrostatic potential-derived charges CHelpG 196... 

Compare electrostatic potential maps for ethyl, 2-propyl, 2-methyl-2-propyl and 2-butyl cations. Does the extent to which positive charge is localized at the carbocation center parallel proton affinity Explain. 

Further, for studying the role of pH and salt concentrations on bulk-electrostatic and non-bulk electrostatic contributions the same approach was made to experiments on the influence of the alcohols mentioned above on the oxygen affinity at various KC1 concentrations and pH-values 144,146). The results obtained indicate that at a low alcohol concentration the bulk-electrostatic contributions are dominant and that with increasing size of the alkyl group, alcohol and KC1 concentration, the nonbulk electrostatic, hydrophobic contributions increase. Recent results of kinetic measurements of 02 release show that cosolvents such as alcohols and formamide influence mainly the allosteric parameter L, i.e. -the equilibrium between T and R conformation and that the separation of the alcohol effects into bulk-electrostatic and hydrophobic (non-bulk electrostatic) contributions is justified. 

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