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Item type:Publication, Access status: with files , N-Heterocyclic carbene vs. thiophene – chiral adsorption and unidirectional rotation on Au(111)(Wiley-VCH, 2025-03-12); ; 32 17 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , N‐heterocyclische carbene mit und ohne thiophen‐substituent: chirale adsorption und unidirektionale rotation auf Au(111)Heterocyclische Carbene sind hocheffektive Liganden zur Verankerung funktioneller organischer Moleküle auf Metalloberflächen und Nanopartikeln, wodurch die Bildung selbstorganisierter Monoschichten erleichtert wird. Ihre Adsorption auf Oberflächen ist jedoch schwer vorherzusagen und zu kontrollieren, und die Geometrie von NHC‐Derivaten auf Goldoberflächen sowie die Rolle von Gold‐Adatomen stehen im Zentrum wissenschaftlicher Diskussionen. Hier präsentieren wir zwei Moleküle welche auf einem Benzimidazol‐NHC Motiv basieren, eines mit einem Thiophen‐Substituenten und das andere mit einem Br‐Atom. Mittels Tieftemperatur‐Rastertunnelmikroskopie (RTM) zeigen wir, dass beide Moleküle planar auf Au(111) adsorbieren und auf der Oberfläche chiral sind. Unsere Ergebnisse deuten darauf hin, dass in beiden Fällen ein Komplex zwischen NHC und einem Gold‐Adatom gebildet wird. Nach Spannungspulsen mit der RTM‐Spitze bewegen sich beide Komplexe durch inelastische Tunnel‐Elektronen. Für das Derivat mit Thiophen beobachten wir eine schrittweise 60°‐Rotation um das S‐Atom in eine Richtung. Die Drehrichtung wird sowohl durch die Chiralität als auch durch die Position des angewendeten Impulses bestimmt. Im Gegensatz dazu bewegt sich das NHC‐Derivat ohne Thiophen lateral auf der Oberfläche. Adsorption, Bindung an Goldatome und Bewegung werden durch Dichtefunktionaltheorie‐Berechnungen und Bildsimulationen unterstützt und diskutiert.Publicationtype: Journal Article10 9 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Thermal with Electronic Excitation for the Unidirectional Rotation of a Molecule on a Surface(2023-08-21); ; ; ; Exploring the limits of the microscopic reversibility principle, we investigated the interplay between thermal and electron tunneling excitations for the unidirectional rotation of a molecule-rotor on the Au(111) surface. We identified a range of moderate voltages and temperatures where heating the surface enhances the unidirectional rotational rate of a chemisorbed DMNI-P rotor. At higher voltage, inelastic tunneling effects dominate, while at higher temperature, the process becomes stochastic. At each electron transfer event during tunneling, the quantum mixing of ground and excited electronic states brings part of the surface thermal energy in the excited electronic states of the molecule-rotor. Thermal energy contributes therefore to the semiclassical unidirectional rotation without contradicting the microscopic reversibility principle.Publicationtype: Journal Article28 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Nanocar and Rotor in One Molecule(2023-02-14); ; ; ; Depending on its adsorption conformation on the Au(111) surface, a zwitterionic single-molecule machine works in two different ways under bias voltage pulses. It is a unidirectional rotor while anchored on the surface. It is a fast-drivable molecule vehicle (nanocar) while physisorbed. By tuning the surface coverage, the conformation of the molecule can be selected to be either rotor or nanocar. The inelastic tunneling excitation producing the movement is investigated in the same experimental conditions for both the unidirectional rotation of the rotor and the directed movement of the nanocar.Publicationtype: Journal ArticleScopus© Citations 5 34 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , STM-induced ring closure of vinylheptafulvene molecular dipole switches on Au(111)(2022-09-20); ; ; ; Dihydroazulene/vinylheptafulvene pairs are known as molecular dipole switches that undergo a ring-opening/-closure reaction by UV irradiation or thermal excitation. Herein, we show that the ring-closure reaction of a single vinylheptafulvene adsorbed on the Au(111) surface can be induced by voltage pulses from the tip of a scanning tunneling microscope. This cyclization is accompanied by the elimination of HCN, as confirmed by simulations. When inducing lateral movements by applying voltage pulses with the STM tip, we observe that the response of the single molecules changes with the ring closing reaction. This behaviour is discussed by comparing the dipole moment and the charge distribution of the open and closed forms on the surface.Publicationtype: Journal Article13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , STM induced manipulation of azulene-based molecules and nanostructures: The role of the dipole moment(2020-12-28); ; ; ; Among the different mechanisms that can be used to drive a molecule on a surface by the tip of a scanning tunneling microscope at low temperature, we used voltage pulses to move azulene-based single molecules and nanostructures on Au(111). Upon evaporation, the molecules partially cleave and form metallo-organic dimers while single molecules are very scarce, as confirmed by simulations. By applying voltage pulses to the different structures under similar conditions, we observe that only one type of dimer can be controllably driven on the surface, which has the lowest dipole moment of all investigated structures. Experiments under different bias and tip height conditions reveal that the electric field is the main driving force of the directed motion. We discuss the different observed structures and their movement properties with respect to their dipole moment and charge distribution on the surface.Publicationtype: Journal ArticleScopus© Citations 9 15