Investigation of Dendrimer Transfer Behaviors at the Micro-Water/1,2-Dichloroethane Interface Facilitated by Dibenzo-18-Crown-6

Abstract

Trans-interfacial behaviors of multiple ionic species at the interface between two immiscible electrolyte solutions (ITIES) are of importance to biomembrane mimicking, chemical and biosensing, and interfacial molecular catalysis. Utilizing host–guest interaction to facilitate ion transfer is an effective and commonly used method to decrease the Gibbs energy of transfer of a target molecule. Herein, we investigated a facilitated ion transfer (FIT) process of poly­(amidoamine)­dendrimer (PAMAM, G0–G2) by dibenzo-18-crown-6 (DB18C6) at the microinterfaces between water and 1,2-dichloroethane (μ-W/DCE). Because of the host–guest interaction between a dendrimer and a ligand, negative shifts of the transfer potentials were observed using cyclic voltammetry or Osteryoung square wave voltammetry. From the FIT behavior of the dendrimer, we revealed that each DB18C6 could selectively coordinate with one amino group. We first evaluated the protonated status of the intermediate state (1:2) exactly under the conditions the dendrimer (G1) transfers across the interface using the electrochemical mass spectrometry (EC-MS)-hyphenated technique, which is much smaller than the protonated status in the water phase (1:8 to 14). Using the same methodology, we also studied the facilitated transfer behaviors of G0 and G2. Based on these results, we put forward the mechanism of the FIT process, which might involve a deprotonating process at the interface for higher-generation dendrimers.

Interface between Two Immiscible Electrolyte Solutions Electrodes for Chemical Analysis

“…An interface between two immiscible electrolyte solutions (ITIES) is a unique electrode, capable of detecting a wide range of electroactive chemical species regardless of their classification as redox-active or redox-inactive. − ITIES electrodes have become more prevalent in analytical science due to their sensitivity beyond redox-active analytes and their ease of fabrication down to the nanoscale, , allowing for high spatial resolution which enables single-entity and nanostructure studies. − Electrochemistry at the ITIES has enabled researchers to probe fundamental mechanistic processes ,,− and a wide range of applications, including catalysis, − cellular studies, − ,,,,− heavy metal detection, − pharmacological studies, ,− …”

Recent Advances in Real‐Time Analysis of Electrochemical Reactions by Electrochemical Mass Spectrometry†

“…Thus, ESI is most widely used in EC‐MS to detect the intermediates and products in the liquid electrolyte solutions. [ 19‐22 ] Based on the original ESI technique, several modified EC‐ESI‐MS ionization devices arose, for instance, electrochemical desorption electrospray ionization MS (EC‐DESI‐MS), [ 6,23‐31 ] electrochemical nano‐ESI‐MS (EC‐nESI‐MS), [ 32‐41 ] electrochemical probe electrospray ionization MS (EC‐PESI‐MS), [ 42 ] electrochemical droplet spray ionization mass spectrometry (EC‐DSI‐MS), [ 43‐45 ] and electrochemistry‐neutral reionization‐mass spectrometry (EC‐NR‐MS). [ 46‐47 ] Additionally, to analyze the gases and volatile analytes, DEMS is also widely employed in EC research, especially in electrocatalysis.…”

Identifying Metal-Oxo/Peroxo Intermediates in Catalytic Water Oxidation by In Situ Electrochemical Mass Spectrometry

“…However, it is hard for them to obtain information on intermediates in electrochemical water oxidation. Another EC-MS method developed by Shao et al combining a hybrid ultramicroelectrode (UME) technique and relay electrospray ionization mass spectrometry realized the detection of short-lived intermediates in a series of complicated EC reactions including electrochemiluminescence, oxygen reduction at liquid/liquid interfaces, and sulfur redox paths in a lithium–sulfur battery. − The in situ EC-MS based on UMEs could be a useful technique to identify intermediates and investigate mechanisms in catalytic water oxidation.…”