A Nanocar and Rotor in One Molecule (original) (raw)

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.

Anchoring Molecular Rotors by On-Surface Synthesis

Building and Probing Small for Mechanics, 2020

Single molecular rotor is an important component for constructing bottom up molecular mechanical machines and a window for shedding light on complex physical and chemical questions about motions of organic molecules on surfaces. Stability of each component in such a molecular construction site is a crucial prerequisite. To realize a stable stepwise rotation of a molecule by a low temperature scanning tunneling microscope (LT-STM), atomic scale axles is particularly important. An ideal atomic scale axle is expected to balance between anchoring and mobility of rotating a single molecule on a metal surface under external excitations. In this Chapter, several chemical anchoring strategies on how to pin a molecular rotor are tested and discussed. Tip-induced manipulation and motion analysis are used as tools to investigate the properties and functionality of the proposed strategies.

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.

Unidirectional molecular motor on a gold surface

Nature, 2005

Molecules capable of mimicking the function of a wide range of mechanical devices have been fabricated, with motors that can induce mechanical movement attracting particular attention 1,2 . Such molecular motors convert light or chemical energy into directional rotary or linear motion 2-10 , and are usually prepared and operated in solution. But if they are to be used as nanomachines that can do useful work, it seems essential to construct systems that can function on a surface, like a recently reported linear artificial muscle 11 . Surface-mounted rotors have been realized and limited directionality in their motion predicted 12,13 . Here we demonstrate that a light-driven molecular motor capable of repetitive unidirectional rotation 14 can be mounted on the surface of gold nanoparticles. The motor design 14 uses a chiral helical alkene with an upper half that serves as a propeller and is connected through a carbon-carbon double bond (the rotation axis) to a lower half that serves as a stator. The stator carries two thiol-functionalized 'legs', which then bind the entire motor molecule to a gold surface. NMR spectroscopy reveals that two photo-induced cis-trans isomerizations of the central double bond, each followed by a thermal helix inversion to prevent reverse rotation, induce a full and unidirectional 3608 rotation of the propeller with respect to the surface-mounted lower half of the system.