Controlled clockwise and anticlockwise rotational switching of a molecular motor

Abstract

The design of artificial molecular machines often takes inspiration from macroscopic machines. However, the parallels between the two systems are often only superficial, because most molecular machines are governed by quantum processes. Previously, rotary molecular motors powered by light and chemical energy have been developed. In electrically driven motors, tunnelling electrons from the tip of a scanning tunnelling microscope have been used to drive the rotation of a simple rotor in a single direction and to move a four-wheeled molecule across a surface. Here, we show that a stand-alone molecular motor adsorbed on a gold surface can be made to rotate in a clockwise or anticlockwise direction by selective inelastic electron tunnelling through different subunits of the motor. Our motor is composed of a tripodal stator for vertical positioning, a five-arm rotor for controlled rotations, and a ruthenium atomic ball bearing connecting the static and rotational parts. The directional rotation arises from sawtooth-like rotational potentials, which are solely determined by the internal molecular structure and are independent of the surface adsorption site.

Room-temperature-concerted switch made of a binary atom cluster

“…It is also noteworthy that the chiral inversion is not a simple rotation or displacement of the whole Pb 3 configuration but rather a complex motion involving two Pb and three Si atoms, where Pb-Si exchanges and Pb-and Si displacements are indeed promoted in concert. This feature is strikingly different from any reported switches involving only single-atom/molecule processes [10][11][12][13][14][15][16][17][18][19][20] , thus being a new type of switch.…”

“…Since this pioneering work, extensive studies using STM/AFM have demonstrated a variety of atomic-scale switches composed of not only an adsorbed atom but also adsorbed molecules and native surface atoms. In all cases, reversible switches could be operated in a controlled way through their single-atom/molecule processes such as lateral/vertical displacements [11][12][13][14] , rotational motions [15][16][17] and conformational changes [18][19][20] . Nevertheless, most switches devised thus far need to be operated at cryogenic temperatures, while controllability at roomtemperature (RT) environment is essential for the many practical applications that await this new technology.…”

Tunable dynamics of a flake on graphene: Libration frequency

“…Since molecular NEMs and nanomechanical devices have shown potential applications in future technologies [2][3][4], the rotational and translational dynamics of these nanoflakes, in particular graphene flakes ("nano" will be omitted in the rest of the text) and molecules have been brought into focus [2,[5][6][7][8][9]. Like an atom switch [10], these single molecules have been shown to execute controlled rotation or translation through the electrical bias exerted by the tip of a scanning tunneling microscope [3,4,11,12]. Additionally, the configurations of the molecules, as well as their dynamics on the monolayer structures, have been imaged clearly by STM [13][14][15][16].…”

Visualization and thermodynamic encoding of single-molecule partition function projections

“…A drawback in MD modelling is the dependence on FF validation, which limits its use to well-known systems. Because of this inherent restriction, a common strategy in singlemolecule experiments has become to calculate zero-temperature potential energy surfaces through ab initio methods and assume their relevance for finite-temperature experiments [25][26][27][28] .…”