Determination of the Local Electric Field at Au/SAM Interfaces Using the Vibrational Stark Effect

Authors
Staffa, Jana K.; Lorenz, Lisa; Stolarski, Michael; Murgida, Daniel Horacio; Zebger, Ingo; Utesch, Tillmann; Kozuch, Jacek; Hildebrandt, Peter
Publication Year
2017
Language
English
Format
article
Status
Published version
Description
A comprehensive understanding of physical and chemical processes at biological membranes requires the knowledge of the interfacial electric field which is a key parameter for controlling molecular structures and reaction dynamics. An appropriate approach is based on the vibrational Stark effect (VSE) that exploits the electric-field dependent perturbation of localized vibrational modes. In this work, 6-mercaptohexanenitrile (C5CN) and 7-mercaptoheptanenitrile (C6CN) were used to form self-assembled monolayers (SAMs) on a nanostructured Au electrode as a simple mimic for biomembranes. The C - N stretching mode was probed by surface enhanced infrared absorption (SEIRA) spectroscopy to determine the frequency and intensity as a function of the electrode potential. The intensity variations were related to potential-dependent changes of the nitrile orientation with respect to the electric field. Supported by electrochemical impedance spectroscopy, molecular dynamics simulations, and quantum chemical calculations the frequency changes were translated into profiles of the interfacial electric field, affording field strengths up to 4 × 108 V/m (C6CN) and 1.3 × 109 V/m (C5CN) between +0.4 and 0.4 V (vs Ag/AgCl). These profiles compare very well with the predictions of a simple electrostatic model developed in this work. This model is shown to be applicable to different types of electrode/SAM systems and allows for a quick estimate of interfacial electric fields. Finally, the implications for electric-field dependent processes at biomembranes are discussed.
Fil: Staffa, Jana K.. Technishe Universitat Berlin; Alemania
Fil: Lorenz, Lisa. Technishe Universitat Berlin; Alemania
Fil: Stolarski, Michael. Technishe Universitat Berlin; Alemania
Fil: Murgida, Daniel Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina
Fil: Zebger, Ingo. Technishe Universitat Berlin; Alemania
Fil: Utesch, Tillmann. Technishe Universitat Berlin; Alemania
Fil: Kozuch, Jacek. Technishe Universitat Berlin; Alemania
Fil: Hildebrandt, Peter. Technishe Universitat Berlin; Alemania
Subject
SEIRA
Stark effect
Electric fields
SAMs
Otras Ciencias Químicas
Ciencias Químicas
CIENCIAS NATURALES Y EXACTAS
Access level
Restricted access
License
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repository
CONICET Digital (CONICET)
Institution
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identifier
oai:ri.conicet.gov.ar:11336/65340