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Abstract

The high aqueous solubility of ionic compounds can be attributed to the ease of solvation of the counter ions. Replacement of the counter ions with ionic detergents dramatically alters the solubility properties of the molecule. Not only does the aqueous solubility drop precipitously, but the solubility in organic phases increases as well. Consequently, the partition coefficient changes by orders of magnitude. This ion pairing phenomenon, which we term hydrophobic ion pairing (HIP), has been extended to polyelectrolytes, such as proteins and polynucleotides. These materials form HIP complexes that dissolve in a range of organic solvents, often with retention of native structure and enzymatic activity. The HIP process has been used to purify protein mixtures, conduct enzymatic reactions in nonaqueous environments, increase structural stability, enhance bioavailability, and prepare new dosage forms.

Chlorhexidine/losartan ionic pair binding and its nanoprecipitation: physico-chemical characterisation and antimicrobial activity

“…Initially, the reaction of Los 2 with Clx 2þ leads to the formation of a cloud suspension, suggesting the formation of nanoparticles (NPs), as observed in other HIP systems (2,3,5). Therefore, DLS titrations were performed in order to investigate the formation of ClxLos 2 at different molar ratios (R ¼ […”

“…The formation of HIPs results in the generation of a lipophilic species with different physical and chemical properties than the original charged organic ions (1)(2)(3)(4)(5).…”

Electronic and relativistic contributions to ion-pairing in polyoxometalate model systems

“…When these increase in size and decrease in charge, they precipitate. Elucidating these processes is foundational to designing effective pharmaceuticals, 1 remediating contamination in the environment, 2 optimizing materials synthesis in water, 3 and growing biological and inorganic crystals from water. 4 Aqueous solubility and ion-pairing is extremely complex because many phenomena are involved including the lattice energy of the crystallized or precipitated solid, the hydration sphere of both the cation and anion, the sum of ions present in solution, and pH effects if the cation and/or anion is a polyatomic oxo-ion.…”

Ion-pairing separation of bioactive peptides using an aqueous/octan-1-ol micro-extraction system from bovine haemoglobin complex hydrolysates

“…Hydrophobic ion pair has been often used for non-aqueous enzyme reactions [14][15][16] or enhanced protein stability in organic solvent [17,18]. Major advantage of hydrophobic ion-pairing is to increase the lipophilicity of hydrophilic molecules [17,19].…”