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Molecular Nanorovers: A roadmap to molecular superlubricity

English title Molecular Nanorovers: A roadmap to molecular superlubricity
Applicant Vilhena Albuquerque D'Orey Jose Guilherme
Number 190731
Funding scheme Spark
Research institution Departement Physik Universität Basel
Institution of higher education University of Basel - BS
Main discipline Condensed Matter Physics
Start/End 01.04.2020 - 31.03.2021
Approved amount 99'060.00
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All Disciplines (2)

Discipline
Condensed Matter Physics
Material Sciences

Keywords (7)

Nano-Manipulation; Friction; Ultra-High-Vacuum; Molecular-Dynamics; Atomic-Force-Microscopy; Nano-Tribology; Scaning-Probe-Microscopy

Lay Summary (German)

Lead
This Spark project will pave the way to direct the motion of single molecules over surfaces via an external electric field. Additionally, we shall meet this ambitious challenge whilst mitigating the friction between the molecule and the surface to a level known as superlubric regime (i.e. an almost frictionless sliding regime).
Lay summary

Das Verständnis und die Choreografie vom „Tanz der Moleküle“ ist eine sehr komplexe Angelegenheit. Angetrieben vom praktischen Interesse, die molekulare Bewegung/Diffusion in der organischen Synthese, Katalyse, etc., zu steuern, sind im Lauf der Geschichte immer wieder einfallsreiche Wege gefunden worden, um die Bewegung von Molekülen zu kontrollieren bzw. zu aktivieren: Früher schlichtweg durch Erwärmen und Umrühren, heute durch Laser und von Mikrowellen gesteuerten, molekularen Strömungen.Eine vergleichbare Kontrolle der molekularen Bewegung an festen Grenzflächen ist jedoch bislang nicht möglich. Das Problem dabei ist die Frage, wie externe Anregungen (wie z. B. Licht, elektrische oder chemische Energie) genutzt werden können, um eine Richtungsbewegung zu erzeugen. In diesem Projekt wollen wir diese Herausforderung angehen, indem wir „atom-by-atom“ Moleküle designen. Es soll nicht nur der Energieverlust (Reibung), der durch die Bewegung der Moleküle auf der Oberfläche entsteht, verringert werden, sondern auch ein passiver, molekularer Motor integriert werden. Unser Molekül wird so konstruiert, dass es drei wichtige Eigenschaften erfüllt: die Wechselwirkung zwischen Molekül und Oberfläche wird verringert; die Bewegung des Moleküls ist durch die Einarbeitung reibungsloser, molekularer Räder lenkbar; und vor allem wird eine dipolare, chemische Gruppe, deren Dipol (über die chemischen Bindungen) senkrecht zur Oberfläche stehen muss, ins Molekül eingeschlossen. Durch Anlegen eines externen, dielektrischen Feldes parallel zur Oberfläche würde das Molekül dann als eine Art nanoskaliges „Segelschiff“ wirken, dessen Segel (die dipolare Gruppe) die Windenergie (das angelegte elektrische Feld) nutzt, um in die gewünschte Richtung zu treiben. Die Erkenntnis aus diesem Projekt würde in hohem Mass Prozessen der Oberflächenchemie zugute kommen, die in vielen Bereichen von entscheidender Bedeutung sind (z. B. Synthese und Katalyse auf der Oberfläche in vielen industriellen und pharmazeutischen Produkten) und ausserdem das Fundament legen, um eine neue Generation von Maschinen (molekulare Maschinen) nutzbar zu machen.

Direct link to Lay Summary Last update: 20.11.2019

Lay Summary (English)

Lead
This Spark project will pave the way to control the motion of single molecules over surfaces via an external electric field. Additionally, we shall meet this ambitious challenge whilst mitigating the friction between the molecule and the surface to a level known as superlubric regime (i.e. an almost frictionless sliding regime).
Lay summary

Understanding and choreographing the dance of molecules is a matter of utmost complexity. Fueled by the practical interest of controlling molecular motion/diffusion in organic synthesis, catalysis, … , throughout history we witnessed ever ingenious ways to control/activate the motion of molecules: from the plain old heating and stirring, up to lasers and microwave guided molecular streams. Yet, a seemingly control of molecular motion at solid interfaces has thus far remained elusive. The challenge stems from understanding how an external stimuli (e.g. light, electrical or chemical energy) can be harnessed to generate directional motion. In this project we aim to meet this ambitious goal by designing molecules atom-by-atom in such way that not only we mitigate energy loss (friction) resulting from their on-surface motion but also we shall incorporate a passive molecular motor. In order to achieve this goal our molecule is designed to meet three important properties: reduce molecule-surface interaction; incorporate frictionless molecular wheels to direct its motion; and importantly to include a dipolar chemical group whose dipole is forced to be perpendicular to the surface (via the chemical bonds). Then by applying an external dielectric field parallel to the surface the molecule would act as a nanoscale Caravel that whose sail, this dipolar group, will harness the energy of the wind (i.e. the applied electric field) in order to propel it along the desired direction. Such understanding would largely benefit surface chemistry processes crucial in a wide range of areas ( e.g. on-surface synthesis and catalysis both key in many industrial and pharmaceutical products) but also will lay the seeds to exploit a new generation of machines (molecular machines).

Direct link to Lay Summary Last update: 20.11.2019

Responsible applicant and co-applicants

Abstract

Understanding and choreographing the dance of molecules is a matter of utmost complexity as not only requires a detailed knowledge of their intricate internal dynamics but also how the latter affects and is influenced by its surroundings. Fueled by the practical interest of controlling molecular motion/diffusion in organic synthesis, catalysis, … , throughout history we witnessed ever ingenious ways to control/activate the motion of molecules: from the plain old heating and stirring, up to lasers and microwave guided molecular streams. Yet, a seemingly control of molecular motion at solid interfaces has thus far remained elusive. The challenge stems from understanding how an external stimuli (e.g. light, electrical or chemical energy) can be harnessed to induce structural modifications or alter molecule-surface interactions in such way that generates motion. Such understanding would benefit not only the surface chemistry at large (e.g. on-surface synthesis and catalysis) but also the growing community of nanoscale synthetic molecular machines since most their biomolecular counterparts operate at interfaces. The difficulty to direct the motion of molecules over surfaces is perhaps best realized considering that in the 1st nanocar/molecular race only two out of 7 world class research groups were able to meet the challenge. This consisted in propelling a molecule (each team could bring its “best contender”) along 100nm in less than 30h!! The sole molecules crossing the finish line required a large amount of time (considering the distance), were very small molecules and used extremely energy inefficient propelling mechanisms. In this project we propose a novel strategy consisting in a bottom-up chemical design of molecules that explore recent advances in superlubricity and physical chemistry allowing to decrease the energy dissipated during the motion by one order of magnitude. Whats more, this will enable to remotely/autonomously propel the molecules along well defined directions using simply an external uniform electric field. To meet this ambitious goal we resort to a synergetic approach combining state of the art 5K Ultra High Vacuum Scanning Probe Microscopy (UHV-SPM) experiments with all atom molecular dynamics simulation (MD) with parameters derived a priory from Quantum Mechanical (QM) calculations. This Spark project will enable the transition of molecular propelling from pulses to fields (STM pulses to uniform electric fields).
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