Whence Molecular Electronics?

Flood, Amar H.; Steuerman, David W.; Heath, James R.

doi:10.1126/science.1106195

Cited by 456 publications

(277 citation statements)

References 17 publications

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“…Negative differential resistance (NDR) and hysteretic resistance switching have been observed in molecule-based devices formed using break junctions 26 , nanopores 27 , scanning probes 28,29 and crossbar structures 14,30,31 . The mechanism of the observed device behaviour has been attributed to several effects, including charge-transfer-induced conformational change [32][33][34] , electromechanical switching 35 , stochastic conformational changes 28 and metal filament formation 29 , where the latter is unrelated to the structures or electrical states of the molecules. This controversy REVIEW ARTICLES | insight about the mechanism of molecule device behaviour may be due in part to the challenges associated with probing molecular states in devices and obtaining well-controlled molecule-electrode interfaces.…”

Section: Memory Elementsmentioning

confidence: 99%

Nanoelectronics from the bottom up

2007

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Section: Memory Elementsmentioning

confidence: 99%

Nanoelectronics from the bottom up

2007

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“…Toward the goal of device applications, switching has been shown to operate in condensed phases such as in a polymer electrolyte gel (12), on a self-assembled monolayer (SAM) (13), on the solid supports of engineered systems (14), and in molecular switch tunnel junctions (15). Bistable rotaxanes benefit from their synthesis being highly modular, a virtue that allows for a considerable degree of flexibility in their design.…”

Section: Olecular Motors Have Recently Garnered Considerable In-mentioning

confidence: 99%

Evaluation of synthetic linear motor-molecule actuation energetics

Brough¹,

Northrop

Schmidt

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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By applying atomic force microscope (AFM)-based force spectroscopy together with computational modeling in the form of molecular force-field simulations, we have determined quantitatively the actuation energetics of a synthetic motor-molecule. This multidisciplinary approach was performed on specifically designed, bistable, redox-controllable [2]rotaxanes to probe the steric and electrostatic interactions that dictate their mechanical switching at the single-molecule level. The fusion of experimental force spectroscopy and theoretical computational modeling has revealed that the repulsive electrostatic interaction, which is responsible for the molecular actuation, is as high as 65 kcal⅐mol ؊1 , a result that is supported by ab initio calculations.computational modeling ͉ force spectroscopy ͉ molecular motors ͉ switchable rotaxanes M olecular motors have recently garnered considerable interest within the domains of microsciences and nanosciences (1, 2). Harnessing the ability to selectively, cooperatively, and repeatedly induce structural changes in molecules may hold the promise of engineered systems that operate with the same complexity, elegance, and efficiency as biological motors function in the human body. In natural systems, it has become apparent that both macro and micro processes are initiated and controlled by nanoscale molecular motors (3). For example, myosin and kinesin are associated with muscle contraction and intracellular trafficking, respectively, and have recently found their ways into engineered devices (4, 5). Moreover, initial work has been performed that demonstrates the ability of natural nanoscale molecular motors to power microfabricated systems (6).Synthetic motor-molecules (7-11), which are designed to excel where their biological counterparts fall short, also have been investigated. Whereas devices powered by biological molecules require (4-6) chemical diffusion for actuation stimulus, synthetic molecules have been shown (2, 9) to operate with a variety of different stimuli, thereby lending much greater flexibility to a particular system's design. Moreover, a synthetic nanoscale actuating molecule carries with it an inherent ability to be modified and optimized precisely for a specific task.Switchable, bistable rotaxanes (2, 9), compounds comprised of a dumbbell-shaped component containing two different recognition sites for an encircling ring-shaped component, show particular promise as molecular actuators, given their ability to undergo controllable, reversible mechanical switching with the appropriate chemical, electrochemical, or photochemical stimulus in solution. Toward the goal of device applications, switching has been shown to operate in condensed phases such as in a polymer electrolyte gel (12), on a self-assembled monolayer (SAM) (13), on the solid supports of engineered systems (14), and in molecular switch tunnel junctions (15). Bistable rotaxanes benefit from their synthesis being highly modular, a virtue that allows for a considerable degree of flexibility in their des...

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“…1) is of the donor-acceptor type that incorporates as one of its ring components the π-electronpoor tetracationic cyclophane, cyclobis(paraquat-p-phenylene) (24-26) (CBPQT 4þ ). The use of redox-active π-electron-rich units [e.g., tetrathiafulvalene (27, 28) (TTF)], along with another π-electron-rich donor [e.g., 1,5-dioxynaphthalene (DNP) in the other ring or dumbbell component], enables electrochemically induced molecular switching, which has been used in a whole variety of applications, such as molecular memory (29,30), microscale mechanical actuation (31), and nanoscale systems that can store and release (32) molecular cargos.…”

mentioning

confidence: 99%

Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry

Fahrenbach

Barnes

Li³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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In donor-acceptor mechanically interlocked molecules that exhibit bistability, the relative populations of the translational isomerspresent, for example, in a bistable [2]rotaxane, as well as in a couple of bistable [2]catenanes of the donor-acceptor vintage-can be elucidated by slow scan rate cyclic voltammetry. The practice of transitioning from a fast scan rate regime to a slow one permits the measurement of an intermediate redox couple that is a function of the equilibrium that exists between the two translational isomers in the case of all three mechanically interlocked molecules investigated. These intermediate redox potentials can be used to calculate the ground-state distribution constants, K. Whereas, (i) in the case of the bistable [2]rotaxane, composed of a dumbbell component containing π-electron-rich tetrathiafulvalene and dioxynaphthalene recognition sites for the ring component (namely, a tetracationic cyclophane, containing two π-electron-deficient bipyridinium units), a value for K of 10 AE 2 is calculated, (ii) in the case of the two bistable [2]catenanes-one containing a crown ether with tetrathiafulvalene and dioxynaphthalene recognition sites for the tetracationic cyclophane, and the other, tetrathiafulvalene and butadiyne recognition sites-the values for K are orders (one and three, respectively) of magnitude greater. This observation, which has also been probed by theoretical calculations, supports the hypothesis that the extra stability of one translational isomer over the other is because of the influence of the enforced side-on donor-acceptor interactions brought about by both π-electron-rich recognition sites being part of a macrocyclic polyether.density functional theory | donor-acceptor molecules | electrochemistry | isomerism | switches T he ability to control the relative motions (1) of molecules is crucial for understanding many biological processes such as cell division and intracellular transport (2), muscle contraction (3), and ATP production (4). This control is essential to the development of potential applications as diverse as catalysis (5), drug delivery (6), elastic materials (7), molecular actuators (8), molecular transport (9), ion sensors (10), motors (11), and information storage (12). Supramolecular chemistry (13) has been one of the sources from which the inspiration and desire to build artificial molecular machines, as the counterpart to biological motors, has sprung. Understanding the mechanism by which intramolecular noncovalent bonding interactions occur-especially in those systems that can undergo reversible switching eventsholds the key to how artificial molecular machines (14) can be engineered to fit the demands of a given function. Gaining intimate knowledge of the mechanisms (15-18) governing the relative molecular motions of their components is, therefore, a pursuit that yields crucial information for the design of artificial molecular machines. Bistable mechanically interlocked molecules (MIMs) [namely, bistable catenanes (19, 20) and rotaxanes (21), wh...

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Whence Molecular Electronics?

Cited by 456 publications

References 17 publications

Nanoelectronics from the bottom up

Nanoelectronics from the bottom up

Evaluation of synthetic linear motor-molecule actuation energetics

Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry

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