Unimolecular rectifiers

Fig. 16 Eleven unimolecular rectifiers studied at the University of Alabama as monolayers between Au electrodes (except for 36d and 36e see text). The arrows indicate the experimentally observed direction favored electron transfer however the direction is reversed for 36d and 36e...

Table 1 Summary data for 11 unimolecular rectifiers studied at the University of Alabama...

Metzger RM (2006) Unimolecular rectifiers and what lies ahead. Colloids Surf A... 

The starting point of molecular electronics was a theoretical model of a unimolecular rectifier proposed in 1974, in which a single molecule consisting of an electron donor region... 

Unimolecular rectifiers are a reality. They have been made and they have been measured. However, there is still substantial room for improvement in the experimental techniques used to study the molecules and in the molecules used to give improved thermal stability. Current experiments need to be modified so that noble metal electrodes may be used to study a dilute monolayer, ideally at low temperature where molecular orbital signatures will be observable. This already has been achieved with robust molecules such as phthalocyanines, which suggests that the technological step to be made is not too great. 

R. M. Metzger, Unimolecular Electronics and unimolecular rectifiers in the Encyclopedia of Supramolecular Chemistry, J. L. Atwood, J. W. Steed (Eds.), Marcel Dekker, New York,... 

This, then, demonstrates the possibility of fabricating a unimolecular rectifier. More details can be found in the summary article [18]. Technical applications... 

Aviram and Ratner proposed that a unimolecular rectifier be a single D-a-A molecule, where D is a good one-electron donor with relatively first low ionization potential, o is some saturated covalent "sigma" bridge,... 

Unlmolecular Electronics and Unimolecular Rectifiers mK experiments on an individual nanotube... 

Aviram and Ratner s proposed D-a-A unimolecular rectifier [14] and the efforts to prepare a practical device are discussed elsewhere in this volume [65]. 

U (for unimolecular ) rectifiers occur when the current passing through a molecule, or monolayer of molecules, involves electron transfers involving molecular orbitals, whose significant probability amplitudes are asymmetrically placed within the chromophore." ... 

Table 1 Summary data for 11 unimolecular rectifiers 11-21 studied at the University of Alabama, table AU compounds were measnred at room temperature in air between An electrodes inside a Faraday cage (11 was also measured earlier between A1 electrodes at 300 also between 105 K and 370 21 was also stndied at 4.2 K). The colnmn pads lists how many independent typical MOM pads were...

R. M. Metzger, The quest for D-cr-A unimolecular rectifiers and related topics in molecular electronics, in Molecular and Biomolecular Electronics, ed. Robert R. Birge, Am, Chem. Soc. Adv. in Chem. Ser. 240, American Chemical Society, Washington, DC, 1994, pp. 81-129. 

R. M. Metzger, Unimolecular rectifiers, in Molecular Nano-electronics, eds. M. A. Reed and T. Lee, American Scientific Publishes, Stevenson Ranch, CA, 2003, pp. 19-38. 

The proposal of using a simple molecular monolayer with donor-acceptor properties as a molecular rectifier [116] initiated a sizable research effort to realize monolayers of suitable molecules using the Lang-muir-Blodgett technique or self-assembly on functionalized substrate surfaces [8,18,139-141,154—157]. Martin et al. recently reported a unimolecular rectifier based on a LB monolayer of a zwitterionic molecule [158]. 

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