Functional molecules in electronic circuits

Abstract

Molecular electronics is a fascinating field of research contributing to both fundamental science and future technological achievements. A promising starting point for molecular devices is to mimic existing electronic functions to investigate the potential of molecules to enrich and complement existing electronic strategies. Molecules designed and synthesized to be integrated into electronic circuits and to perform an electronic function are presented in this article. The focus is set in particular on rectification and switching based on molecular devices, since the control over these two parameters enables the assembly of memory units, likely the most interesting and economic application of molecular based electronics. Both historical and contemporary solutions to molecular rectification are discussed, although not exhaustively. Several examples of integrated molecular switches that respond to light are presented. Molecular switches responding to an electrochemical signal are also discussed. Finally, supramolecular and molecular systems with intuitive application potential as memory units due to their hysteretic switching are highlighted. Although a particularly attractive feature of molecular electronics is its close cooperation with neighbouring disciplines, this article is written from the point of view of a chemist. Although the focus here is largely on molecular considerations, innovative contributions from physics, electro engineering, nanotechnology and other scientific disciplines are equally important. However, the ability of the chemist to correlate function with structure, to design and to provide tailor-made functional molecules is central to molecular electronics.

Electrochemical Control of Single-Molecule Conductance by Fermi-Level Tuning and Conjugation Switching

“…17,[34][35][36] Figure 1b The small spike at log (G/G 0 ) ≈ -2.2 in panels e and f represents an artefact related to the switching of the amplifier. 37 Figure 1c shows typical conductance-distance traces of AQ-1,5 in the reduced and oxidized states obtained from the STM-BJ experiment.…”

Shape‐Switchable Azo‐Macrocycles

“…[136] The electrochemical grafting of specific organic molecules has become a method of choice since the deposition conditions can be easily controlled and adapted to the substrate. The surface immobilization proceeds via the electrochemical formation of highly reactive aryl radical species by the loss of N 2 (a in Scheme 6).…”

“…Thus conjugated molecules, either as single molecule wires, [136][154] [156] or as polymers, [259]- [262] have received considerable attentions as potential functional subunits or materials in emerging areas such as molecular electronics, [263] photovoltaics, [264] [265] or light emitting systems. [266] A detailed understanding of the structural factors controlling electron transport processes is not only of fundamental interest, but also a crucial requirement for the development of design criteria.…”

“…[136][153]- [157] Single molecules in electronic circuits can be integrated in various experimental setups to measure their conductance. Such measurements enable basic investigations of the correlation between the molecular structure and transport properties.…”

“…[146] This type of reaction is widely applied to introduce divers functional group in organic chemistry, material science and molecular electronics. [136][146] [147] The Sonogashira reaction is a palladium catalyzed coupling reaction with a copper(I) salt as co-catalyst. [148][149] The catalytic cycle of the reaction is displayed in Scheme 7.…”