A nanomechanical device based on linear molecular motors (original) (raw)

A nano-chemo-mechical actuator based on artifical molecular machines

18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005., 2005

The success of future molecule -driven actuators most likely lies in the development of artificial molecular motors because of their ability to provide large forces from low voltage inputs while also featuring bistable actuation characteristics and molecular design flexibility. With these advantages in mind, we have developed a mechanical device utilizing the force produced from the relative movement of artificial molecular motors -rotaxanes -in conjunction with a hybrid top-down/bottom-up fabrication approach. This process has produced insight into the promise but also the limitations of molecule-driven actuators which inspires redirected efforts for an eventually optimized new class of multiscale mechanical, optical, and medical devices.

A Mechanical Actuator Driven Electrochemically by Artificial Molecular Muscles

Acs Nano, 2009

A microcantilever, coated with a monolayer of redox-controllable, bistable [3]rotaxane molecules (artificial molecular muscles), undergoes reversible deflections when subjected to alternating oxidizing and reducing electrochemical potentials. The microcantilever devices were prepared by precoating one surface with a gold film and allowing the palindromic [3]rotaxane molecules to adsorb selectively onto one side of the microcantilevers, utilizing thiol-gold chemistry. An electrochemical cell was employed in the experiments, and deflections were monitored both as a function of (i) the scan rate (<20 mV s ؊1 ) and (ii) the time for potential step experiments at oxidizing (>؉0.4 V) and reducing (<؉0.2 V) potentials. The different directions and magnitudes of the deflections for the microcantilevers, which were coated with artificial molecular muscles, were compared with (i) data from nominally bare microcantilevers precoated with gold and (ii) those coated with two types of control compounds, namely, dumbbell molecules to simulate the redox activity of the palindromic bistable [3]rotaxane molecules and inactive 1-dodecanethiol molecules. The comparisons demonstrate that the artificial molecular muscles are responsible for the deflections, which can be repeated over many cycles. The microcantilevers deflect in one direction following oxidation and in the opposite direction upon reduction. The ϳ550 nm deflections were calculated to be commensurate with forces per molecule of ϳ650 pN.

Linear Artificial Molecular Muscles

Journal of the American Chemical Society, 2005

Two switchable, palindromically constituted bistable rotaxanes have been designed and synthesized with a pair of mechanically mobile rings encircling a single dumbbell. These designs are reminiscent of a "molecular muscle" for the purposes of amplifying and harnessing molecular mechanical motions. The location of the two cyclobis(paraquat-p-phenylene) (CBPQT 4+ ) rings can be controlled to be on either tetrathiafulvalene (TTF) or naphthalene (NP) stations, either chemically ( 1 H NMR spectroscopy) or electrochemically (cyclic voltammetry), such that switching of inter-ring distances from 4.2 to 1.4 nm mimics the contraction and extension of skeletal muscle, albeit on a shorter length scale. Fast scan-rate cyclic voltammetry at low temperatures reveals stepwise oxidations and movements of one-half of the [3]rotaxane and then of the other, a process that appears to be concerted at room temperature. The active form of the bistable [3]rotaxane bears disulfide tethers attached covalently to both of the CBPQT 4+ ring components for the purpose of its self-assembly onto a gold surface. An array of flexible microcantilever beams, each coated on one side with a monolayer of 6 billion of the active bistable [3]rotaxane molecules, undergoes controllable and reversible bending up and down when it is exposed to the synchronous addition of aqueous chemical oxidants and reductants. The beam bending is correlated with flexing of the surfacebound molecular muscles, whereas a monolayer of the dumbbell alone is inactive under the same conditions. This observation supports the hypothesis that the cumulative nanoscale movements within surface-bound "molecular muscles" can be harnessed to perform larger-scale mechanical work. J. AM. CHEM. SOC. 2005, 127, 9745-9759 9 9745 (9) For examples of chemically controllable molecular machines, see (a) Lane, A. S.; Leigh, D. A.; Murphy, A. Ballardini, R.; Balzani, V.; Baxter, I.; Credi, A.; Fyfe, M. C. T.; Gandolfi, M. T.; Gómez-López, M.; Martínez-Díaz, M.-V.; Piersanti, A.; Spencer, N.; Stoddart, J. F.; Venturi, M.; White, A. J. P.; Williams, D. J. Raehm, L.; Sauvage, J.-P.; Divisia-Blohorn, B.; Vidal, P.-L. Inorg. Chem. 2000, 39, 1555-1560. (k) Ballardini, R.; Balzani, V.; Dehaen, W.; Dell'Erba, A. E.; Raymo, F. M.; Stoddart, J. F.; Venturi, M. Eur. J. Org. Chem. 2000, 591-602. (l) Collin, J.-P.; Kern, J.-M.; Raehm, L.; Sauvage, J.-P. Molecular Switches; Feringa, B. L., Ed.; Wiley-VCH: Weinheim, 2000; pp 249-280. (m) Altieri, A.; Gatti, F. G.; Kay, E. R.; Leigh, D. A.; Paolucci, F.; Slawin, A. M. Z.; Wong, J. K. Y. J. Am. Chem. Soc. 2003, 125, 8644-8654. (n) Poleschak, I.; Kern, J.-M.; Sauvage, J.-P. Chem. Commun. 2004, 474-476. For examples of optically controllable molecular machines, see: (o) Ballardini, R.; Balzani, V.; Gandolfi, M. T.; Prodi, L.; Venturi, M.; Philp, D.; Ricketts, H. G.; Stoddart, J. F. Angew. Chem., Int. Ed. Engl. 1993, 32, 1301-1303. (p) Ashton, P. R.; Ballardini, R.; Balzani, V.; Credi, A.; Dress, R.; Ishow, E.; Kocian, O.; Preece, J. A.; Spencer, N.; Stoddart, J. F.; Venturi, M.; Wenger, S. Chem. Eur. J. 2000, 6, 3558-3574. (q) Brouwer, A. M.; Frochot, C.; Gatti, F. G.; Leigh, D. A.; Mottier, L.; Paolucci, F.; Roffia, S.; Wurpel, G. W. Len, S.; Wong, J. K. Y.; Bottari, G.; Altieri, A.; Morales, M. A. F.; Teat, S. J.; Frochot, C.; Leigh, D. A.; Brouwer, A. M.; Zerbetto, F.

Molecular Motors, Actuators, and Mechanical Devices

Atomically precise manufacturing systems, such as those described in Nanosystems [1], will utilize molecular motors and actuators 1 that drive components to perform useful work. The conversion of electrical and chemical energy into mechanical motion is facilitated by the use of gears, bearings, drive shafts, springs, and so forth, to direct the motion of components and minimize energy losses. Thus, research efforts dedicated to produce these sorts of components are considered to be both a direct pathway in our Roadmap and an enabler of other pathways that can take advantage of these molecular mechanical devices and the fabrication techniques developed to produce them. This section summarizes the state-of-the-art in the construction of these devices and describes their relevance to the Roadmap. Table 3 at the end of this section provides a summary of representative molecular motors, actuators, and mechanical devices.

Controlling Motion at the Nanoscale: Rise of the Molecular Machines

ACS Nano, 2015

As our understanding and control of intra-and intermolecular interactions evolve, ever more complex molecular systems are synthesized and assembled that are capable of performing work or completing sophisticated tasks at the molecular scale. Commonly referred to as molecular machines, these dynamic systems comprise an astonishingly diverse class of motifs and are designed to respond to a plethora of actuation stimuli. In this Review, we outline the conditions that distinguish simple switches and rotors from machines and draw from a variety of fields to highlight some of the most exciting recent examples of opportunities for driven molecular mechanics. Emphasis is placed on the need for controllable and hierarchical assembly of these molecular components to display measurable effects at the micro-, meso-, and macroscales. As in Nature, this strategy will lead to dramatic amplification of the work performed via the collective action of many machines organized in linear chains, on functionalized surfaces, or in three-dimensional assemblies.

Optomechanical control of molecular motors

SPIE Proceedings, 2010

The majority of mechanisms that can be deployed for optical micromanipulation are not especially amenable for extension into the nanoscale. At the molecular level, the rich variety of schemes that have been proposed to achieve mechanical effect using light commonly exploit specific chemical structures; familiar examples are compounds that can fold by cis-trans isomerization, or the mechanically interlocked architectures of rotaxanes. However, such systems are synthetically highly challenging, and few of them can realistically form the basis for a true molecular motor. Developing the basis for a very different strategy based on programmed electronic excitation, this paper explores the possibility of producing controlled mechanical motion through optically induced modifications of intermolecular force fields, not involving the limitations associated with using photochemical change, nor the high intensities required to produce and manipulate optical binding forces between molecules. Calculations reveal that significant, rapidly responsive effects can be achieved in relatively simple systems. By the use of suitable laser pulse sequences, the possibilities include the generation of continuous rotary motion, the ultimate aim of molecular motor design.

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

MRS Bulletin, 2009

Recent developments in chemical synthesis, nanoscale assembly, and molecular-scale measurements enable the extension of the concept of macroscopic machines to the molecular and supramolecular levels. Molecular machines are capable of performing mechanical movements in response to external stimuli. They offer the potential to couple electrical or other forms of energy to mechanical action at the nano- and molecular scales. Working hierarchically and in concert, they can form actuators referred to as artificial muscles, in analogy to biological systems. We describe the principles behind driven motion and assembly at the molecular scale and recent advances in the field of molecular-level electromechanical machines, molecular motors, and artificial muscles. We discuss the challenges and successes in making these assemblies work cooperatively to function at larger scales.

Controlled Rotary Motion in a Monolayer of Molecular Motors

Angewandte Chemie International Edition, 2007

Rotary molecular motors are ubiquitous in natural systems where they are used for diverse tasks including molecular transport, cellular translocation, and ATP synthesis, and are considered key components of future synthetic nanomechanical devices. In many of these systems, such as ATPase or the bacterial flagella motor, immobilization into the cellular membrane allows their rotary action to be harnessed. Attaching biological or synthetic molecular rotary motors to solid substrates is considered to be a key step toward the fabrication of devices that exploit the collective rotational mechanical motion generated by these systems. Although linear synthetic and biological motors have been mounted on surfaces, examples of surface-bound rotary motors are scarce. Preliminary work to this end includes the successful characterization of functioning ATPase while immobilized on quartz and recently, a single example of synthetic rotary molecular motors functioning on gold nanoparticles in solution. Although the latter is a significant step toward future applications, the nanoparticles in solution are still overwhelmed by Brownian rotation and translation, and the motor function might to some extent suffer from excitedstate quenching by the gold, making it difficult to harness work from the system.

Shuttles and Muscles: Linear Molecular Machines Based on Transition Metals

Accounts of Chemical Research, 2001

Transition-metal-containing rotaxanes can behave as linear motors at the molecular level. The molecules are set into motion either by an electrochemical reaction or using a chemical signal. In a first example, a simple rotaxane is described that consists of a ring threaded by a two-coordination-site axle. The ring contains a bidentate ligand, coordinated to a copper center. The axle incorporates both a bidentate and a terdentate ligand. By oxidizing or reducing the copper center to Cu(II) or Cu(I) respectively, the ring glides from a given position on the axle to another position and vice versa. By generalizing the concept to a rotaxane dimer, whose synthesis involves a quantitative double-threading reaction triggered by copper(I) complexation, a molecular assembly reminiscent of a muscle is constructed. By exchanging the two metal centers of the complex (copper(I)/zinc(II)), a large-amplitude movement is generated, which corresponds to a contraction/stretching process. The copper(I)-containing rotaxane dimer is in a stretched situation (overall length ∼8 nm), whereas the zinc(II) complexed compound is contracted (length ∼6.5 nm). The stretching/contraction process is reversible and it is hoped that, in the future, other types of signals can be used (electrochemical or light pulse) to trigger the motion.