Ion Transfer at Nanointerfaces between Water and Neat Organic Solvents

Abstract

Nanopipet voltammetry was used for the first study of ion transfer (IT) reactions between aqueous solutions and neat organic solvents. An extremely wide ( approximately 10 V) polarization window obtained with no electrolyte added to the organic phase allows one to probe charge transfer reactions, which are not normally accessible by electrochemical techniques, for example, the transfer of l-alaninamide cation from water to 1,2-dichloroethane (DCE). While anions (e.g., chloride) and relatively hydrophobic cations (e.g., tetraalkylammonium ions) can be transferred from water to less polar neat solvents such as DCE, the transfers of strongly hydrated metal cations occur only in the presence of organic supporting electrolyte.

Free Energy for the Permeation of Na+ and Cl− Ions and Their Ion-Pair through a Zwitterionic Dimyristoyl Phosphatidylcholine Lipid Bilayer by Umbrella Integration with Harmonic Fourier Beads

“…3,19 However, compelling evidence suggests that certain charged carriers facilitate ion transport via the ion-pairing mechanism. 20−22 One of the requirements of such facilitated permeation is “transient interfacial ion-pairing”. 20−22 Using the three PMFs computed in this study, we are able to assess for the first time the change in the ion-pairing free energy as a function of the ion-pair permeation depth.…”

“…(17) Furthermore, contrary to earlier works based on continuum electrostatics theories 3,18,19 a growing number of recent papers argue that ion permeation could in fact be assisted by ion-pairing. 17,20−22 Because of the labile nature of the interactions, “transient interfacial ion-pairing” has been proposed to explain shuttling of hydrophilic ions across bilayer. 20−22 …”

“…17,20−22 Because of the labile nature of the interactions, “transient interfacial ion-pairing” has been proposed to explain shuttling of hydrophilic ions across bilayer. 20−22 …”

Investigation of transfer behavior of protonated pyridine at the liquid/liquid interface using dual micropipettes

“…While studies of charge transfer reactions with micropipettes have attracted considerably attentions recently [7][8][9][10][11][12], the size of the liquid/liquid interface has been further miniaturized to a few nanometers with quartz pipettes and improvement of pulling programs [13]. The possibility was demonstrated, with nano-liquid/liquid interface, of completely reducing the iR drop and performing measurements without supporting electrolytes [14,15]. This actually opened a new route of applying various organic solvents to the investigations of charge transfer processes at a liquid/liquid interface [16].…”

Electrochemical sensing and imaging based on ion transfer at liquid/liquid interfaces

“…The k 0 values are still much lower than a high mass transfer coefficient of 35 cm/s based on the steady-state diffusion of the crown ether ionophore from the external 1,2-dichloroethane (DCE) solution to the nanopipet-supported ITIES with the smallest radius of 5 nm [28]. The small current at the nanoscopic ITIES minimizes the ohmic potential drop to enable the study of IT at the relatively resistive ITIES systems based on low-electrolyte [30, 31] or electrolyte-free [32–34] media. For quantitative studies, an inlaid disk-shaped ITIES was formed at the tip of a well silanized nanopipet [35] to yield a limiting current, i ss , as given by…”