Molecular wires electron transport

Emberly EG, Kirczenow G (2002) Molecular spintronics spin-dependent electron transport in molecular wires. Chem Phys 281 (2—3) 311—324... 

Yaliraki SN, Ratner MA (1998) Molecule-interface coupling effects on electronic transport in molecular wires. J Chem Phys 109(12) 5036-5043... 

Widawsky JR, Kamenetska M, Klare J, Nuckolls C, Steigerwald ML, Hybertsen MS, Venkataraman L (2009) Measurement of voltage-dependent electronic transport across amine-linked single-molecular-wire junctions. Nanotechnology 20 434009... 

It is useful to introduce a nomenclature for distinguishing between ET occurring by the conduction and superexchange mechanisms. The term electron transport is used in the context of molecular wire behavior, while electron transfer is used in the context of the superexchange mechanism. 

A. Nitzan and M. A. Ratner, Electron transport in molecular wire junctions, Science 300, 1384—1389 (2003). 

Models describing the transport of electrons in molecular junctions have been shown to be quite powerful. Here the emphasis was put on time-dependent effects which can, for example, be triggered by external laser fields. If these fields are strong, a non-perturbative treatment of the laser-matter interaction is of large importance and is included in the presented TL QME. Also the connection of transport through molecular wires or coherent laser control scenarios may play an important role in the future. 

In contrast, a new type of redox polymer-coated electrode has recently been fabricated using the bottom-up method, in which redox-active molecules are connected with molecular wires, and the wires act as the current collector.11-13 In this case, electrons can be transported through the wires, and control of the electron transfer pathway is possible by changing the structure of the molecular wires. If the wire has a linear structure, redox active molecules with the wire connections exhibit a structure similar to that of a beaded curtain (Fig. lb), in which the electron transfers in a straightforward manner along each line. Furthermore, when the wire is composed of redox active molecules, we observe the promising phenomenon that the electron transfers via the redox process in the wire, whose mechanism would... 

B. Electron Transport Behavior of the Molecular Wires on the Electrode... 

While molecular assembly has proven to be effective for a photoelectric conversion system, coordination reactions are possibly a simple approach for connecting such functional molecules, as presented in the previous section. We applied the stepwise coordination method to prepare a photoelectric conversion system. Since the molecular wire exhibits redox conduction through the wire,11,13 efficient photo-electron transport through the redox sites in the wire is also expected. In this section, we demonstrate the fabrication of a photoelectric conversion system using ITO electrodes modified with M(tpy)2 (M = Co, Fe, Zn) complex wires with a terminal porphyrin moiety as a photosensitizer. The behavior of photo-electron transfer from porphyrin to ITO through the molecular wire was investigated by changing the metal element in the M(tpy)2 moieties.14... 

Now, as we have defined wire-like transport by a motion that is assisted by molecular bridges, we may proceed to the mechanistic point of view. In particular, we will contrast theoretical results with experimental data for molecular wire-like behavior in regard to the transfer of electronic charge and/or energy. Intramolecular electron-transfer (ET) rate constants characterize the charge transport in DBA conjugates and in electronic transport junction we can apply the word conductance . 

Now upon establishing the theoretical framework for the description of molecular-wire behavior, we should analyze the transport phenomena as a function of molecular-wire properties. Firstly, we will discuss the superexchange mechanism. The latter is considered as the main mechanism for efficient electron-transfer within the photosynthetic reaction center [37, 38] and has been studied in various biomimetic systems [39, 40]. 

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