Effect of Hofmeister Anions on Interfacial Properties of Mica Surface in Concentrated Aqueous Solution

The electric double layer (EDL) formed at the water/solid interface is the key to understanding a wide variety of natural phenomena; and nowadays, this knowledge may lead to ideas for technological innovations in the industrial and biomedical fields. The properties of the EDL on a surface directly determine the performance of an EDL-based device. In electrolyte solution, the coions with the same charge sign with the surface are usually ignored. However, they are expected to make a considerable contribution in concentrated conditions when ionic specific effects should be considered. Herein, we investigated the effect of anions in the Hofmeister series, including kosmotropes (Ac−), chaotropes (I−), and intermediate (Cl−), on the properties of the EDL on a negatively charged mica surface by observing intersurface forces using the surface forces apparatus (SFA). The SFA results indicated that at a concentration of 1 M and above, the effect of the monovalent anions in the sodium solutions were mainly correlated with their hydration behaviors. Exclusively in the solutions with strongly hydrated anions, we measured the abnormal long-range repulsions in the diffuse layer region farther away from the surface. By further investigating the solutions with kosmotropic divalent SO42− at relatively low concentrations, we may attribute the observation to the formation of ion pairs and hydrodynamic effects in the presence of concentrated kosmotropic anions. Moreover, these anions can also contribute to the formation of a complete and stable hydration layer near the surface. This work demonstrates the considerable effects of Hofmeister anionic coions on the properties of a simple colloid interface, which has attracted little attention in the past. Therefore, further investigations are desirable in the development of electrolytes and surface materials for the promising EDL-based technologies.

Superior thermally robust energetic materials featuring Z–E isomeric bis(3,4-diamino-1,2,4-triazol-5-yl)-1H-pyrazole: self-assembly nitrogen-rich tubes and templates with Hofmeister anion capture architecture

A super thermally robust nitrogen-rich framework was synthesized, and Z → E isomerization as well as supramolecular assembly inclusion strategy gave rise to two different nitrogen-rich tubes and templates with Hofmeister anions capture architecture.

The effect of Hofmeister anions on water structure at protein surfaces

To understand the effects of specific ions on protein–water interactions and the thermodynamic stability of proteins in salt solutions, we use a molecular dynamics (MD) simulation to examine the water structure, orientational distribution, and dynamics near the surface of ubiquitin.

Regulation of the growth, morphology, mechanical properties and biocompatibility of natural polysaccharide-based multilayers by Hofmeister anions

Herein the optimization of the physicochemical properties and surface biocompatibility of polyelectrolyte multilayers of the natural, biocompatible and biodegradable, linear polysaccharides hyaluronan and chitosan by Hofmeister anions was systematically investigated.