The Anion Series

A representative anion Hofmeister series, resulting from elution from a Sephadex G-10 column, was shown by Collins and Washabaugh in their often quoted review 

Another version of the series was reported by Cacace et al. (1997) in their subsequent 

A more comprehensive series is obtained by convolution (Marcus 2009) of the various series (Collins and Washabaugh 1985 Cacace et al. 1997 Pinna et al. 2005 Zhang and Cremer 2006)  

The phenomena described by means of the Hofmeister anion series cover a very broad spectrum. They range from the original one of protein precipitation to salting out of other solutes, enzyme activity, macromolecular conformational transitions. 

Cacace et al. (1997) stressed several aspects of the Hofmeister series. The underlying concept is that biopolymer interactions are water-mediated and the anions affect both the surface of the biopolymer and the structure of the water. When a protein folds, aggregates or adsorbs, the solvent/protein interfacial area Awp is diminished. Contrarily, when a protein is denatured, Awp increases. Work needs to 

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Reaction of 13a with elemental Li in Et20 yields 15a, the first derivative of the simplest polyhedral closo-carborane of the anionic series [CH(BH) ] (n = 4) (Scheme 3.2-9). Polyhedral members with n = 3 are transition states of type 5 as shown in Section 3.2.2.1. 

Recently we found that the presence of ions introduces artifacts in the determination of pH by pyranine (54). This effect is related to the relative position of the ion (both cations and anions) in the Hoffmeir series (54). Compared with other ions, AS was found to have only a minimal effect on this shift, which agrees well with the location of NH4+ in the cation Hoffmeir series and of sulfate in the anion series (54). 

Information on unoccupied orbital electronic structure is available from the XANES of silicates. Although few data are available for olivines, studies of the anion series C104, S04, PO4 , as described in Bianconi (1988), indicate them to have structures similar to SiF4, with a, and L absorptions below threshold, and e and resonances in the continuum (Tossell et al., 1985a Tossell, 1987). Si XANES for Mg2Si04 are... 

It is generally agreed that Na" ", being near the midpoint of the series, has a minimal effect therefore it is almost universally used to study the anions effects of salts. Since also Cl, in the middle of the anion series (5.6) has a minimal effect, it is usually used to study the specific cation effects of a series of salts. 

Similar considerations hold for the negative component nucleate. Acid functions as well as basic functions are present in the molecule but the acid ones far and away predominate. In the acid medium in which the complex combinations are investigated one must however take account of positive charges. If the attachment of anions to these is strong then this can lead to reversal of the anion series. 

We shall see later (p. 396, 3f) that on replacing the aqueous medium by water-alcohol or water-acetone mixtures similar term displacements can occur in this series of three terms (p. 398, Fig. 43) as we have discussed above for the terms of the anion series with the positive ichthyocoll sol. 

Finally it appears that salts can also have a suppressive action according to the double valency rule , in which naturally the abbreviations of the series of terms of the cations already discussed in 3c (p. 391) and anomalous sequences of these terms occur. Compare Fig. 43 which relates to the flocculation with 2 m. eq. per 1 Co(NH3)0Cl8 throughout in various acetone concentrations. Here the suppressive actions of the two first terms of the cation series (2 — 1 and 1 — 1) and of the anion series (1 —2 and 1 — 1) have been investigated. 

While therefore abnormalities occur in the series of terms of the cations, the order of the terms in the anion series ... 

The order of the terms of the anion series is perfectly normal 1—3 ) 1—2 > 1—1 and the curves for 1 — 3 and 1 — 2 completely suppress the turbidity. This happens because this suppression occurs at smaller concentrations than NaCl and consequently... 

Figures 4 and 5 also appear to give the same overall picture insofar as they both show the nonionic and nonionic-anionic classes to be less efficient at lowering DST than the anionic class, though differentials appear to be greater in Fig. 5. However, the two definitions of efficiency are measuring slightly different things. (yi 5) demonstrates that the most efficient compounds from the anionic series are 0.27-0.31 of log unit in concentration more efficient than the corresponding compounds from either the nonionic or nonionic-anionic series. This effectively says that twice as much nonionic or nonionic-anionic is required relative to the anionic to reach the...

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]. 

Sodium ions, near the midpoint of the series, have a minimal effect as have chloride ions in the anion series. The order for the monatomic alkali metal cations does not agree with their sizes, charge densities, or their lyotropic series (Table 8.11). However, cases where the lyotropic series is followed are also known. The rate of the penetration of the alkali metal cations through leaf cuticles decreases in the order Cs > Rb > > Na > Li according to McFarlaneand Berry [105] and the critical... 

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