Electrochemically controlled self-assembled monolayers characterized with molecular and sub-molecular resolution

Abstract

Self-assembled organization of functional molecules on solid surfaces has developed into a powerful and sophisticated tool for surface chemistry and nanotechnology. A number of reviews on the topic have been available since the mid 1990s. This perspective article aims to focus on recent development in the investigations of electronic structures and assembling dynamics of electrochemically controlled self-assembled monolayers (SAMs) of thiol containing molecules on gold surfaces. A brief introduction is first given and particularly illustrated by a Table summarizing the molecules studied, the surface lattice structures and the experimental operating conditions. This is followed by discussion of two major high-resolution experimental methods, scanning tunnelling microscopy (STM) and single-crystal electrochemistry. In Section 3, we briefly address choice of supporting electrolytes and substrate surfaces, and their effects on the SAM structures. Section 4 constitutes the major body of the article by offering some details of recent studies for the selected cases, including in situ monitoring of assembling dynamics, molecular electronic structures, and the key external factors determining the SAM packing. In Section 5, we give examples of what can be offered by theoretical computations for the detailed understanding of the SAM electronic structures revealed by STM images. A brief summary of the current applications of SAMs in wiring metalloproteins, design and fabrication of sensors, and single-molecule electronics is described in Section 6. In the final two sections (7 and 8), we discuss the current status in understanding of electronic structures and properties of SAMs in electrochemical environments and what could be expected for future perspectives.

An electrochemical approach to fabricate a heterogeneous mixed monolayer on planar polycrystalline Au and its characterization with Lateral Force Microscopy

“…There have been many investigations on the characterization and manipulation of alkylthiol SAMs on noble metals and the properties of the interface have been included in a variety of reviews [3][4][5][6][7][8]. Recently, the interest in Au-thiol chemistry has been renewed due its relation to nanotechnology as it was discovered that alkylthiols are efficient stabilizing ligands for gold nanoparticles (AuNPs) [9].…”

Differentiating Amino Acid Residues and Side Chain Orientations in Peptides Using Scanning Tunneling Microscopy

“…Thus, although proteins, 26–29 peptides, 30–40 and other biomolecules 41 assembled on surfaces have been imaged using the STM, distinguishing amino acid sidechain conformations in peptides adopting biologically relevant conformations ( i.e. , β sheets or α helices) has proven challenging.…”

Modulation of electrochemical hydrogen evolution rate by araliphatic thiol monolayers on gold

“…To understand this complex interplay, it is essential to understand the interfacial properties of SAM-modified electrodes under electrochemical conditions. In this context, the influence of the electrode potential on formation kinetics [16, 17], structural properties [18–20], and ionic permeability of SAMs has been subject to several works [19, 21]. Especially electrochemical desorption/readsorption studies revealed important details concerning the nature of the interfacial interactions between a chemisorbed monolayer and a metallic substrate, besides defining the applicable potential range for SAM-modified electrodes.…”