Switchable molecular devices

In principle any molecule able to exist in two reversible, switchable states can represents a molecular switch (bistable device) with potential to form part of molecular circuitry or act as molecular memory. An excellent component for switchable molecular devices is the 1,2-dithienylethene system, which has been exploited ingeniously by Lehn in a number of bistable systems.54 The core switching element is the transformation of the dithienylethene unit between two stable states as a function of the wavelength of incident radiation (Scheme 11.8). 

Switchable Molecular Devices From Rotaxanes to Nanoparticles... 

Bissell RA, Cordova E, Stoddart JF, Kaifer AE (1995) Advantages of the rotaxane framework for the construction of switchable molecular devices. In Becher J, Schaumburg K (eds) Molecular engineering for advanced materials. NATO ASI Series Kluwer Academic Publishers, chap 2... 

Liu J (2001) Switchable Molecular Devices From Rotaxanes to Nanoparticles 99 141-162 Livage J, see Henry M (1991) 77 153-206... 

The signal-triggered functions of these molecular assemblies have to be first characterized in bulk solution. Then, extensive efforts have been directed to integrate these photoswitchable chemical assemblies with transducers in order to tailor switchable molecular devices. The redox properties of photoisomerizable mono-layers assembled on an electrode surface are employed for controlling interfadal electron transfer [16]. Specifically, electrical transduction of photonic information recorded by photosensitive monolayers on electrode supports can be used in developing monolayer optoelectronic systems [16-19]. Electrodes with receptor sites exhibiting controlled binding of photoisomerizable redox-active substrates from the solution [20] also allow the construction of molecular optoelectronic devices. 

The work summarized in this article relates to some of the most exciting areas of supramolecular chemistry. The interdependence of electron-transfer reactions with supramolecular interactions is at the core of the development of switchable molecular devices. Furthermore, research in areas of supramolecular electrochemistry may open the way for technological applications such as responsive (intelligent) materials. A possible impact in the field of electrochemical sensors is also readily visualized from the work described here. 

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