The Anion Hofmeister Series

1 The Anion Hofmeister Series A comprehensive anion Hofmeister series is obtained by convolution of the various series proposed by several authors, Collins and Washabaugh [94], Miti et al. [97], Cacace et al. [98], Pinna et al. [99], and Zhang and Cremer [100], resulting in  

Inversions of the positions of some anions in the series are noted when several related phenomena are nsed to establish it as reported by Cacace et al. and by Pinna et al. [98, 99], For instance, F was placed at the head of the series according to Hochachka and Somero [101] and to HaU and Drake [102], althongh other authors relegated it to nearer its middle. A related series, whose lyotropic numbers are given in Table 8.11, also has several reversals with respect to the Hofmeister series as pointed out by Schott [103] and by Lo Nostro et al. [104]. 

Anion properties that could be relevant to their ordering in the Hofmeister series, arbitrarily arranged according to their molar refractivities, 7 , are shown in Table 8.12. The reader confronted with an anion Hofmeister series for some biophysical phenomenon may att pt to correlate it with the listed anion properties. 

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It is furthermore concluded that whereas the anion Hofmeister series is generally well established, with only few reversals that can be explained ad-hoc, this is not the case regarding the cation Hofmeister series. There are in general no head cations established in a series such as (5.8), erroneously termed chaotropic, nor general tail cations , erroneously termed cosmotropic, but for each surface the hydrophilic and hydrophobic character or balance between these properties is responsible for the order of cations interacting directly with sites at the surface, in addition to the ion properties mentioned above, see Table 5.4 for the latter. 

Leontidis E, Aroti A (2009) Liquid expanded monolayers of lipids as model systems to understand the anionic Hofmeister series 2. Ion partitioning is mostly a matter of size. J Phys Chem B 113 1460-1467... 

Leontidis E, Aroti A, Belloni L (2009) Liquid expanded monolayers of lipids as model systems to understand the anionic Hofmeister series 1. A tale of model. J Phys Chem B 113 1447-1459 Levitsky VY, Panova AA, Mozhaev VV (1994) Correlation of high-temperamre stability of a-chymotrypsin with salting-in properties of solution. Eur J Biochem 219 231-236 Lipkind GM, Fozzard HA (2008) Voltage-gated Na channel selectivity the role of the conserved domain III lysine residue. J Gen Physiol 131 523-529 Lo Nostro P Fratoni L, Ninham BW, Baglioni P (2002) Water absorbency by wool fibers Hofmeister effect. Biomacromolecules 3 1217-1224... 

Most potentiometric anion-selective electrodes are based on anion exchangers such as quaternary ammonium salts. The selectivity pattern of these sensors correlates with anion lipophilicity. Highly hydrated anions such as fluoride, bicarbonate and chloride are difficult to monitor due to significant interference from more lipophilic anions like perchlorate, salicylate and nitrate which may be present in the analyzed sample. The anions can be classified according to their lipophilicity resulting in the classical Hofmeister series (ClOi > SCN > salicylate > I > NOJ > Br >... 

Schwierz N, Horineck D, Netz RR (2010) Reversed anionic Hofmeister series the interplay of surface charge and surface polarity. Langmuir 26 7370-7379 Shchori E, Nae N, Jagur-Grodzinski J (1975) Stabihty constants of metal cations with dibenzo-18-crown-6 in aqueous solutions. J Chem Soc Dalton Trans 1975 2381-2386 Smith PE (1999) Computer simulation of cosolvent effects on hydrophobic hydration. J Phys Chem B 103 525-534... 

Schwierz N, Horinek D, Netz RR (2010) Reversed anionic Hofmeister series the interplay of surface charge and surface polarity. Langmuir 26 7370... 

The observed ion-specific effects were associated with the hydrophobicity of the ions and the ions affinity to the polyelectrolyte. Later, Khtzing et al. explained this effect by the difference between cosmotropic and chaotropic ions [37]. The influence of specific anions on certain properties of PEMs has been investigated extensively by Salomaki et al. [28-30]. The anions tested within this work followed the famous Hofmeister series and gave an increasing storage shear modulus with increasing ion size. The latter result is in contradiction to the increase in chain mobihty found later by Nazaran et al. [24]. 

The Cation Hofmeister Series The nature of the cations of the salts used for the denaturation of proteins also plays a role, subordinate to the dominating role of the anions, establishing for a given anion the series according to Cacace et al. [98] ... 

Note Some of Grahame s values for and included in this table. For a common cation, the sequence of anions in order of increasing adsorption is similar to that of the Hofmeister series in coagulation studies, and it is evident that specific adsorption properties are involved. 

S ts can be used to precipitate proteins by salting out effects. The effectiveness of various salts is determined by the Hofmeister series, with anions being effective in the order citrate > PO4" > SO4" > CH3COO > Cl > NO3 , and cations according to NH4 > > Na ... 

The order of cations and anions regarding these structure breaking and making properties is related to their position in the lyotropic or Hofmeister series, such as... 

COAGULATION (Hofmeister Series). A definite order of arrangement of anions and cations according lo their powers of coagulation when their salts are added in quantity lo lyophilic sols. Thus, the order of cations... 

A. Aroti, E. Leontidis, M. Dubois, and T. Zemb. Effects of monovalent anions of the Hofmeister series on DPPC lipid bilayers part I Swelling and in-plane equations of state. Biophys../., 93(5) 1580-1590, 2007. 

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