Simultaneous and coordinated rotational switching of all molecular rotors in a network

Zhang, Yuan; Kersell, Heath; Stefak, Roman; Echeverría, Jorge; Iancu, Violeta; Perera, U.G.E.; Li, Yichao; Deshpande, Aparna; Braun, Kai; Joachim, Christian; Rapenne, Gwénaël; Hla, Saw‐Wai

doi:10.1038/nnano.2016.69

Cited by 89 publications

(81 citation statements)

References 37 publications

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“…On the side of the molecule, it may be necessary to lift the active part from the surface to avoid strong surface interactions. These could be accomplished by double decker designs [96][97][98][99] that put the switching part on top of anchoring groups such as tripodal metal-based ligands. [96,97,100] We note that it may be possible to extend these design principles to other switching molecules.…”

Section: Discussionmentioning

confidence: 99%

Photochromic Diarylethenes Designed for Surface Deposition: From Self‐Assembled Monolayers to Single Molecules

et al. 2019

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The efficient switching that can occur between two stable isomers of diarylethenes makes them particularly promising targets for opto‐ and molecular electronics. To examine these classes of molecules for electronics applications, they have been subjected to a series of scanning tunneling microscopy (STM) experiments, which are the focus of this Review. A brief introduction to the chemical design of diarylethenes in terms of their switching capabilities along with the basics of STM are presented. Next, initial STM studies on these compounds under ambient conditions are discussed. An overview of how molecular design affects the isomerization and self‐assembly of diarylethenes at the solid‐liquid interface as investigated by STM is then presented, as well as single‐molecule studies under ultrahigh vacuum. The last section presents further prospects for molecular design in the field.

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Section: Discussionmentioning

confidence: 99%

Photochromic Diarylethenes Designed for Surface Deposition: From Self‐Assembled Monolayers to Single Molecules

et al. 2019

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“…by using current pulses [6,[10][11][12], voltage pulses [13,14] or mechanical way [15,16] in a scanning tunneling microscope (STM) [17][18][19]. Meanwhile, diverse milestones have been achieved such as stepby-step molecular rotation [20], controlling the rotational direction of a molecular rotor [21], and collective rotation effects [22,23], among others [24][25][26][27]. However, the underlying physical mechanisms leading to unidirectional molecular rotation are not well understood, since they involve in general terms a delicate interplay between collective mechanical and electronic degrees of freedom.…”

Section: Introductionmentioning

confidence: 99%

Current-induced rotations of molecular gears

Lin

Joachim

2019

J. Phys. Commun.

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Downsizing of devices opens the question of how to tune not only their electronic properties, but also of how to influence 'mechanical' degrees of freedom such as translational and rotational motions. Experimentally, this has been meanwhile demonstrated by manipulating individual molecules with e.g. current pulses from a Scanning Tunneling Microscope tip. Here, we propose a rotational version of the well-known Anderson-Holstein model to address the coupling between collective rotational variables and the molecular electronic system with the goal of exploring conditions for unidirectional rotation. Our approach is based on a quantum-classical description leading to effective Langevin equations for the mechanical degrees of freedom of the molecular rotor. By introducing a timedependent gate to mimic the influence of current pulses on the molecule, we show that unidirectional rotations can be achieved by fine tuning the time-dependence of the gate as well as by changing the relative position of the potential energy surfaces involved in the rotational process. idea by going beyond the linear coupling regime and, more importantly, by considering a non-harmonic, periodic potential energy surfaces associated with a collective rotational degree of freedom rather than with the linear displacement of the standard AHM. Our basic assumption is that the movement of the tip of a Scanning Tunneling Microscope (STM) can act as an effective time-dependent electrical gate for a molecule deposited on the substrate, being able to generate a current-induce rotation. The setup we are envisioning is displayed in figure 1: a single molecule adsorbed on a metallic substrate is electrically addressed by the STM tip. This gate is able to change the average occupation of the relevant electronic state coupled to the collective rotational variable (s) and it may thus trigger a (possibly) unidirectional rotation of the molecule. Specifically, we can design two PESs with a given separation of minima and choose an appropriate switching of the gate to make the molecule rotate one-way. To address this problem, we use a quantum-classical approach to the problem, by considering the rotational degrees of freedom as classical variables, whose dynamics is governed by a generalized Langevin equation, while, on the other hand, the electronic system is treated within the nonequilibrium Green function (NEGF) technique exploiting methods developed in the context of current-induced forces [39][40][41][42][43][44][45].The outline of the article is as follows: in section 2, the rotational analogy of the AHM Hamiltonian is formulated and the corresponding equation of motion and the reduced density matrix are discussed. In section 3, a simple example of a planar molecule with N-fold symmetry is considered. By performing an adiabatic expansion in the reduced density matrix, we derive an equation of motion in the adiabatic limit, which allows simplifying the problem and leading to the concept of mean torque, damping, and external-driving torque. Consequently, it e...

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“…Metalloporphyrins are of great interest as they can work as building blocks reacting with other molecular systems in order to build supramolecular structures (Choi et al, 2008;Choi & Frisbie, 2010;Sedghi et al, 2011;Ferreira et al, 2014Ferreira et al, , 2011Zhang et al, 2016). The properties of porphyrins have been a subject of research due to their extraordinary stability given by the four pyrrole groups connected by methine units and a reactive metallic centre enabling charge transfer and coordination to other molecules (Zou et al, 2005;Zou & Chen, 2008).…”

Section: Introductionmentioning

confidence: 99%

Sparse‐coding denoising applied to reversible conformational switching of a porphyrin self‐assembled monolayer induced by scanning tunnelling microscopy

Oliveira

Bragança

Alcácer

et al. 2018

Journal of Microscopy

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Scanning tunnelling microscopy (STM) was used to induce conformational molecular switching on a self-assembled monolayer of zinc-octaethylporphyrin on a graphite/tetradecane interface at room temperature. A reversible conformational change controlled by applying a tip voltage was observed. Consecutive STM images acquired at alternating tip voltages showed that at 0.4 V the porphyrin monolayer presents a molecular arrangement formed by alternate rows with two different types of structural conformations and when the potential is increased to 0.7 V the monolayer presents only one type of conformation. In this paper, we characterize these porphyrin conformational dynamics by analyzing the STM images, which were improved for better quality and interpretation by means of a denoising algorithm, adapted to process STM images from state of the art image processing and analysis methods. STM remains the best technique to 'see' and to manipulate the matter at atomic scale. A very sharp tip a few angstroms of the surface can provide images of molecules and atoms with a powerful resolution. However, these images are strongly affected by noise which is necessary to correct and eliminate. This paper is about new computational tools specifically developed to denoise the images acquired with STM. The new algorithms were tested in STM images, obtained at room temperature, of porphyrin monolayer which presents reversible conformational change in function of the tip bias voltage. Images with high resolution, acquired in real time, show that the porphyrins have different molecular arrangements whether the tip voltage is 0.4 V or 0.7 V.

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Simultaneous and coordinated rotational switching of all molecular rotors in a network

Cited by 89 publications

References 37 publications

Photochromic Diarylethenes Designed for Surface Deposition: From Self‐Assembled Monolayers to Single Molecules

Photochromic Diarylethenes Designed for Surface Deposition: From Self‐Assembled Monolayers to Single Molecules

Current-induced rotations of molecular gears

Sparse‐coding denoising applied to reversible conformational switching of a porphyrin self‐assembled monolayer induced by scanning tunnelling microscopy

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