Mechanical Shuttling of Linear Motor-Molecules in Condensed Phases on Solid Substrates

Huang, Tony Jun; Tseng, Hsian‐Rong; Sha, Lin; Lu, Weixing; Brough, Branden; Flood, Amar H.; Yu, Bo; Celestre, Paul C.; Chang, Jane P.; Ho, Chih‐Ming

doi:10.1021/nl035099x

Cited by 116 publications

(87 citation statements)

References 36 publications

(21 reference statements)

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“…AFM-based dynamic force spectroscopy studies were performed at standard temperature and pressure with a Multimode scanning probe microscope with a Nanoscope 3A controller and Pico Force system (Digital Instruments͞Veeco Probes, Santa Barbara, CA), both in degassed 200 proof EtOH and in the presence of an oxidizing solution of 10 Ϫ4 M Fe(ClO 4 ) 3 in EtOH, which is consistent with previous work that demonstrated mechanical molecular switching within highly packed rotaxane-based thin films (14). Samples were exposed to the oxidant for no less than 10 min to ensure oxidation of the surface bound molecules but no more than 90 min to guarantee the integrity of the SAM.…”

Section: Synthesis Of Dumbbell-shaped Compound 3 and [2]rotaxane R⅐4pf6supporting

confidence: 72%

“…3b) summarizes the results of force probing in the presence of a 10 Ϫ4 M Fe(ClO 4 ) 3 oxidizing enthanolic solution, which has been shown to induce ring translation to the 1,5-dioxynaphthalene (DNP) site as a result of electrostatic repulsion from the TTF 2ϩ site (14). Whereas in the unoxidized situation the histogram reveals a singular force, this histogram indicates that there are two distinct force barriers, one at 66 pN (O1, solid blue curve) and the other at 145 pN (O2, solid green curve).…”

Section: Resultsmentioning

confidence: 99%

“…(a) The CBPQT 4ϩ ring, which carries a tether terminated by a thioctic acid ester for attachment to a gold-coated AFM tip, displays a stronger interaction with TTF than with DNP and thus resides selectively (16) on the former. (b) Chemical oxidation of TTF to TTF 2ϩ results in a strong charge-charge repulsion between the CBPQT 4ϩ ring and TTF 2ϩ , a situation that causes the CBPQT 4ϩ ring to shuttle to DNP (9,(12)(13)(14)(15)(16) in the oxidized [2]rotaxane R 6ϩ . The mechanical movement of the CBPQT 4ϩ ring from TTF 2ϩ to DNP resembles the power stroke of a linear motor.…”

Section: Resultsmentioning

confidence: 99%

“…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%

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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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Section: Synthesis Of Dumbbell-shaped Compound 3 and [2]rotaxane R⅐4pf6supporting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Olecular Motors Have Recently Garnered Considerable In-mentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of synthetic linear motor-molecule actuation energetics

Brough¹,

Northrop

Schmidt

et al. 2006

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

Self Cite

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show abstract

“…The development of molecular motors have received a large attention [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] since the beginning of nanotechnology. Molecular motors can be designed to move inside liquids, viscous media or soft matter.…”

Section: Introductionmentioning

confidence: 99%

Folding time dependence of the motions of a molecular motor in an amorphous medium

et al. 2017

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We investigate the dependence of the displacements of a molecular motor embedded inside a glassy material on its folding characteristic time τ f . We observe two different time regimes. For slow foldings (regime I) the diffusion evolves very slowly with τ f , while for rapid foldings (regime II) the diffusion increases strongly with τ f ( D ≈ τ −2 f ) suggesting two different physical mechanisms. We find that in regime I the motor's displacement during the folding process is counteracted by a reverse displacement during the unfolding, while in regime II this counteraction is much weaker. We notice that regime I behavior is reminiscent of the scallop theorem that holds for larger motors in a continuous medium. We find that the difference in the efficiency of the motor's motion explains most of the observed difference between the two regimes. For fast foldings the motor trajectories differ significantly from the opposite trajectories induced by the following unfolding process, resulting in a more efficient global motion than for slow foldings. This result agrees with the fluctuation theorems expectation for time reversal mechanisms. In agreement with the fluctuation theorems we find that the motors are unexpectedly more efficient when they are generating more entropy, a result that can be used to increase dramatically the motor's motion.

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Rotaxanes and Catenanes

Davis

Higson

2011

Macrocycles

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Mechanical Shuttling of Linear Motor-Molecules in Condensed Phases on Solid Substrates

Cited by 116 publications

References 36 publications

Evaluation of synthetic linear motor-molecule actuation energetics

Evaluation of synthetic linear motor-molecule actuation energetics

Folding time dependence of the motions of a molecular motor in an amorphous medium

Rotaxanes and Catenanes

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