Aviram-Ratner rectifier

UE began with Aviram and Ratner s 1973 proposal for a molecular rectifier this is the third rectification process [79]. An Aviram-Ratner rectifier has donor and acceptor groups in one molecule, separated by an insulating bridge of sigma... 

Wang B, Zhou Y, Ding X et al (2006) Conduction mechanism of Aviram-Ratner rectifiers with single pyridine-s-Cgo oligomers. J Phys Chem B 110 24505-24512... 

The demonstration of molecular electronics has been really difficult, as can be seen for the Aviram-Ratner rectifier. The only molecular device that has been demonstrated experimentally is the molecular photodiode, by Fujihira et al. [5-7]. In the course of time, the term molecular electronics has acquired a broader definition, such as that of being the field in which organic molecular materials perform an active function in the processing and its transmission and storage [8]. 

Luis AA, Jacob G, Christian W, Nicholas K (2012) Aviram-Ratner rectifying mechanism for DNA base-pair sequencing through graphene nanogaps. Nanotechnology 23 135202... 

The Aviram-Ratner D-ct-A molecule is analogous to a pn junction rectifier the electron-rich donor region D would be similar to the electron-rich semiconducting n region, while the electron-poor A region would be similar to a semiconductor s p region [79]. However, note that under forward bias the preferred direction of Aviram-Ratner electron flow is from A to D, while in a pn junction rectifier the preferred direction is from n to p. 

Among the early potential rectifiers studied, one of us (Mattem) designed the D-cr-A molecule 37 (Fig. 17), whose multilayer conductivity was measured by the Sambles group [99]. Multilayers gave striking rectification, with RR = 130. Current flow was in the anti-Aviram-Ratner direction, however, and having an assembly of multilayers rather than a monolayer complicated the interpretation of the results [99]. 

Characteristic IV curves at room temperature are shown in Fig. 18, and some of the results are summarized in Table 1. These results have been reviewed often [11, 12]. Efforts were made to identify the molecular mechanisms for the rectification, and to buttress them by theoretical calculations [39, 76, 106, 112]. Not all compounds tested rectified, because of their chemical structure and/or monolayer structure. The direction of larger electron flow ( forward direction ) is shown by arrows in Fig. 16 it is noteworthy that in all cases the direction is from the electron donor D to the electron acceptor A, that is, in the anti-Aviram-Ratner direction. 

Fig. 15 A molecular OR gate, whose chemical structure maps the electrical circuit diagram shown in Fig. 20a. Two Aviram-Ratner molecular rectifier chemical groups have been bonded to a central chemical node. This intramolecular circuit with one simple node can be easily designed, because the node Kirchoff node law is valid here. Note that the molecular orbital of each partner can be still identified on the 2 T(E) because of their weak interactions through the CH2 bridge. This is not always the case. The obtained logic surface demonstrates an OR function for well-selected values of the input voltage, but with two logical level 1 outputs which would have to be corrected using an additional output circuit...

One of the most famous molecular devices is the Aviram-Ratner molecular rectifier using a molecule of the type D-o--A, shown in Fig. 1 [2,3]. If a molecule (supermolecule) of this type is assembled and sandwiched between two metal electrodes, it is expected to work as a rectifier since the energy necessary to allow the electron transfer reaction shown in Eq. (1) to proceed is considered to be several eV lower than the one shown... 

It is reasonable to assume that any molecule that has an asymmetry in its electronic structure, such as carbon monoxide, is potentially a molecular rectifier. An Aviram and Ratner rectifier is merely an extension of this principle in that it is a modular assembly of parts which are well understood from charge transfer studies. The electronic asymmetry of the rectifier is obtained by placing an electron donor at one end of the molecule and an electron acceptor at the other. Some common... 

Figure 1.38. The Aviram-Ratner molecular rectifier. A. Aviram and M. Ratner, Chem. Phys. Lett. 29, 111 (1974).

Aviram A, Ratner MA (1974) Molecular rectifiers. Chem Phys Lett 29(2) 277-283... 

Aviram and Ratner s originally proposed D-a-A molecule (or Gedankenmolekiil ), 35 (Fig. 14), included the excellent donor TTF (27) and the excellent acceptor TCNQ (33), separated by a rigid bicyclooctane bridge [79]. This molecule was never made (and would likely not have made a good monolayer), but it was the impetus for the synthesis of many new candidate rectifiers. 

Aviram A, Ratner MA (1974) Molecular rectifiers. Chem Phys Lett 29 277-283 Viani L, dos Santos MC (2006) Comparative study of lower fullerenes doped with boron and nitrogen. Solid State Commun 138 498-501... 

A. Aviram, M.A. Ratner, Molecular Rectifiers , Chem. Phys. Lett., 29,277 (1974)... 

Figure 4. The energy levels of an Aviram and Ratner molecular rectifier [8]. a) Zero applied field, ground state configuration b) forward bias c) reverse bias (note that reverse > forward) d) reverse bias, alternative mechanism.

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