Chaotropic and Kosmotropic Anions Regulate the Outcome of Enzyme-Mediated Dynamic Combinatorial Libraries of Cyclodextrins in Two Different Ways

We demonstrate how different anions from across the Hofmeister series can influence the behavior of enzyme-mediated dynamic combinatorial libraries of cyclodextrins (CDs). Using cyclodextrin glucanotransferase to catalyze reversible transglycosylation, dynamic mixtures of interconverting cyclodextrins can be formed wherein the relative concentrations of α-CD, β-CD and γ-CD is determined by their intrinsic stabilities and any stabilizing influences of added template (guest) molecules. Here, we find that addition of high concentrations of kosmotropic anions can be used to enhance the effects of added hydrophobic templates, while chaotropic anions can themselves act as templates, causing predictable and significant changes in the cyclodextrin composition due to weak, but specific, binding interactions with α-CD.

Kosmotropic anion for improving cycling stability of aqueous lithium-ion batteries in salt-in-water electrolytes

The incompatibility between Li+-intercalated electrodes and water limits the practical feasibility of aqueous lithium-ion batteries (LIBs), which are economical and environmentally benign energy storage systems. Tremendous amounts of salts dissolved in water (water-in-salt) have been utilized to mitigate the access of water to the electrode/electrolyte interface and to extend the electrochemical potential window of aqueous LIBs. However, this approach has low viability owing to the expense of the salts. Here, we show that kosmotropic anions with moderate concentrations (0.5 ~ 3 mol kg− 1) protect the LiCoO2 electrode by harnessing water molecules. The sulfates of kosmotropic anions develop rigid water-solvation shells and also form ion pairs with Li+. All-atomic-level multiscale simulation revealed that sulfates tied with Li+ and the water shell are highly concentrated at the interface, thus decreasing the density of free water. The suppressed water activity explains the superior cell performance achieved with 0.5 mol kg− 1 sulfate relative to that in cells with 1 mol kg− 1 of chaotropic anions such as nitrate, perchlorate, and bis(trifluoromethylsulfonyl)imide. The formation of a liquid-phase protective layer is a new concept for developing stable aqueous batteries without the requirement for a solid-state electrolyte or an artificial protective layer on the electrode.

The many-body expansion for aqueous systems revisited: III. Hofmeister ion–water interactions

We report a Many Body Energy (MBE) analysis of aqueous ionic clusters containing kosmotropic and chaotropic anions and cations at the two opposite ends of the Hofmeister series to quantify how these ions alter the interaction between the water molecules in their immediate surroundings.

pH- and chaotropic anion-induced conformational changes of tertiary amine-containing binary heterografted star molecular bottlebrushes in aqueous solution

Three-arm star-shaped, tertiary-amine-containing bottlebrushes exhibit star-globule shape transitions in response to pH changes and addition of sufficiently strong chaotropic anions.

Theoretical Considerations and the Microelectrophoresis Experiment on the Influence of Selected Chaotropic Anions on Phosphatidylcholine Membrane Surface Charge Density

Influence of sodium salts of selected chaotropic anions from the Hofmeister series (NaCl, NaBr, NaNO3, NaI) on the surface charge density of phosphatidylcholine membranes was studied. Small unilamellar lipid vesicles were used as a model system in the investigations. The theoretical and experimental approach to the interactions between inorganic anions and phosphatidylcholine membranes is presented. Experimental membrane surface charge densities data were determined as a function of pH of the aqueous electrolytes using microelectrophoresis method. The quantitative description of the interactions between zwitterionic phosphatidylcholine membrane and monovalent anions is presented. The equilibria constants of the binding of solution ions onto phospholipid surface were calculated. Knowledge of these parameters was essential to determine the theoretical membrane surface charge density values. The theoretical data were compared to the experimental ones in order to verify the mathematical model. Both approaches indicate that the anion-phosphatidylcholine membrane interaction increases with the size of the anion. The adsorption of chaotropic anions to membranes was found to follow the Hofmeister series I− > NO3− > Br− > Cl−.