Position and Orientation Control of a Photo- and Electrochromic Dithienylethene Using a Tripodal Anchor on Gold Surfaces

Abstract

A tripodal system for anchoring photochromic dithienylethenes on gold surfaces is reported. The self-assembled monolayers of a tripod-functionalized dithienylethene were characterized by cyclic voltammetry, surface-enhanced Raman spectroscopy (SERS), and X-ray photoelectron spectroscopy (XPS). These data are compared with solution studies, solid state Raman spectroscopy, and density functional theory (DFT) calculations. We show that the tripod-functionalized dithienylethene forms stable monolayers on gold in which all three legs of the tripod are adsorbed via the thiol units, thus providing a fixed position and orientation of the dithienylethene moiety with respect to the surface. Importantly, immobilization in this way allows for retention of both the photochemical and electrochemical functionality of the dithienylethene unit and reduces photochemical fatigue observed in solution.

Photochromic Diarylethenes Designed for Surface Deposition: From Self‐Assembled Monolayers to Single Molecules

“…These could be accomplished by double decker designs [96][97][98][99] that put the switching part on top of anchoring groups such as tripodal metal-based ligands. [96,97,100] We note that it may be possible to extend these design principles to other switching molecules.…”

“…On the side of the molecule, it may be necessary to lift the active part from the surface to avoid strong surface interactions. These could be accomplished by double decker designs that put the switching part on top of anchoring groups such as tripodal metal‐based ligands . We note that it may be possible to extend these design principles to other switching molecules.…”

Carbazole‐Based Tetrapodal Anchor Groups for Gold Surfaces: Synthesis and Conductance Properties

“…In this work, we present a new tetrapodal anchoring motif designed to bind strongly to gold surfaces and form ordered self‐assembled monolayers (SAMs) with well‐spaced conductive backbones. Inspired by tripodal systems,– multiple anchoring points are incorporated into our design to ensure efficient surface binding. In contrast to many current approaches, we aimed to separate these additional anchoring points from the conductive backbone of the molecule and avoid sp 3 ‐hybridisation in the conductive pathway.…”

“…In contrast to many current approaches, we aimed to separate these additional anchoring points from the conductive backbone of the molecule and avoid sp 3 ‐hybridisation in the conductive pathway. We note that while this study focuses on the molecular electronics applications of our new anchoring motif, it may also prove adaptable as a useful scaffold for other applications, for example, gold surface‐assemblies of optoelectronic materials, switches or polymerisation initiators …”

Characterisation of dihydroazulene and vinylheptafulvene derivatives using Raman spectroscopy: The CN-stretching region

“…In order to control the switching properties of the DHA/VHF photochromic system knowledge about the influence of substitution is important. Raman spectroscopy has previously been used to monitor photoswitching of other photochromic systems and pericyclic ring-openings [17][18][19][20][21][22]. Infrared (IR) spectroscopy has also previously been used to investigate the DHA-X/VHF-X photochromic system in the solid state; however, for some of the compounds the IR absorbance was too weak to detect [23].…”