Dimerization Boosts One-Dimensional Mobility of Conformationally Adapted Porphyrins on a Hexagonal Surface Atomic Lattice

Eichberger, M.; Marschall, Matthias; Reichert, Joachim; Weber-Bargioni, A.; Auwärter, Willi; Wang, R. L. C.; Kreuzer, H. J.; Pennec, Yan; Schiffrin, Agustin; Barth, Johannes V.

doi:10.1021/nl802995u

Cited by 67 publications

(85 citation statements)

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“…Using scanning tunnelling microscopy (STM) investigations, molecular-level characterization of individual diffusing species became possible 41 . Notably the translation or rotational motions of aromatic flat-lying species could be followed in exquisite detail, and evidence appeared that the formation of supramolecules or nanoarchitectures leads to special mobility scenarios where intermolecular interactions sensitively interfere 27,42,43 .…”

Section: Resultsmentioning

confidence: 99%

Visualization and thermodynamic encoding of single-molecule partition function projections

et al. 2015

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Ensemble averaging of molecular states is fundamental for the experimental determination of thermodynamic quantities. A special case occurs for single-molecule investigations under equilibrium conditions, for which free energy, entropy and enthalpy at finite temperatures are challenging to determine with ensemble averaging alone. Here we report a method to directly record time-averaged equilibrium probability distributions by confining an individual molecule to a nanoscopic pore of a two-dimensional metal-organic nanomesh, using temperaturecontrolled scanning tunnelling microscopy. We associate these distributions with partition function projections to assess real-space-projected thermodynamic quantities, aided by computational modelling. The presented molecular dynamics-based analysis is able to reproduce experimentally observed projected microstates with high accuracy. By an in silico customized energy landscape, we demonstrate that distinct probability distributions can be encrypted at different temperatures. Such modulation provides means to encode and decode information into position-temperature space.

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Section: Resultsmentioning

confidence: 99%

Visualization and thermodynamic encoding of single-molecule partition function projections

et al. 2015

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“…These can also be transformed into the corresponding entropy values, as shown by Eichberger et al, when investigating an unexpectedly fast surface diffusion of 2HTPyP dimers on Cu(111). 33 As an outlook, we want to stress the importance of the results by Buchner et al, 34 Eichberger et al 33 and Ditze et al 37 achieved by UHV STM, which demonstrate that entropic effects have to be generally considered for large organic molecules on surfaces at and close to RT. The general character of these investigations is underlined by recent STM experiments at the liquid/ solid interface.…”

Section: Discussionmentioning

confidence: 96%

“…33,34,36,37,[53][54][55][56][57][58] The reason for the very peculiar adsorption behaviour of these free base porphyrins on Cu(111) is a strong site-specific attractive interaction between the iminic nitrogen atoms of the porphyrin macrocycle and the Cu substrate atoms; this specific interaction was already suspected in ref. 33 and 55 and later on verified by XPS. 58 In the following, the specific role and interplay of adsorbate-substrate and adsorbateadsorbate interactions of different tetraphenylporphyrins (2HTPP and CoTPP) on Ag (111) and Cu(111) will be discussed.…”

Section: Diffusion and Rotation Of 2htppmentioning

confidence: 99%

“…4,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] In this contribution, we review recent advances in the understanding of the dynamic behaviour of porphyrins, as representatives of organic molecules, adsorbed on a Cu(111) single crystal surface in ultra-high vacuum (UHV). Based on temperaturedependent measurements of individual molecules, the kinetics and energetics of diffusion 33,34 and rotation, 34 of the so-called self-metalation reaction 35,36 and finally of conformational switching of particular free base porphyrins 37 can be determined. Even though these processes appear to be very different at first glance, they can all be regarded as activated processes, as schematically sketched in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature

Marbach

Steinrück

2014

Chem. Commun.

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Scanning tunnelling microscopy (STM) enables us to directly observe the dynamic behaviour of organic molecules on surfaces. While imaging atoms and molecules using STM is certainly fascinating by itself, corresponding temperature-dependent measurements allow for the quantitative determination of the energetics and kinetics of the underlying molecular surface processes. Herein, we review recent advances in the STM investigation of the dynamic behaviour of adsorbed porphyrins at and close to room temperature.Three different case studies are discussed, providing insight into the dynamics of diffusion, rotation, reaction, and molecular switching at surfaces, based on isothermal STM measurements. The reviewed examples demonstrate that variable temperature STM can be a suitable tool to directly monitor the dynamic behaviour of individual adsorbed molecules, at and close to room temperature. Free base porphyrins on Cu(111) proved to be particularly suitable for these studies due to the strong bonding interaction between the iminic nitrogen atoms in the porphyrin macrocycle and the Cu substrate atoms. As a consequence, the corresponding activation energies for surface diffusion, self-metalation reaction and conformational switching are of a magnitude that allows for monitoring the processes at and around room temperature, in contrast to most previous studies, which were performed at cryogenic temperatures. The kinetic analysis of the surface diffusion and self-metalation was performed using an Arrhenius approach, yielding the corresponding activation energies and preexponential factors. In contrast, the conformational switching process was analysed in the framework of transition state theory, based on the Eyring equation. This approach provides a more detailed insight into interpretable thermodynamic potentials, i.e., the enthalpic and entropic contributions to the activation barrier. The analysis shows that at room temperature the adsorption and switching behaviour of the investigated free base porphyrin on Cu(111) is dominated by entropic effects. Since the entropic energy contribution vanishes at low temperatures, the importance of experiments conducted at temperatures close to room temperature is emphasized.

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“…Nevertheless, at E b = 0.20 eV the simulated island density is higher than experimental results in the low temperature regime. This difference may be given by the diffusion of dimeric clusters, 18 an effect ignored in our simulations. There are more dimers in low temperature than in high temperature and thus the influence of dimer diffusion is more obvious in this regime.…”

Section: B Kmc Simulationmentioning

confidence: 99%

Combined scanning tunneling microscopy and kinetic Monte Carlo study on kinetics of Cu-coordinated pyridyl-porphyrin supramolecular self-assembly on a Au(111) surface

Lin

2011

Phys. Rev. B

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We have studied the kinetics of Cu-coordinated pyridyl-porphyrin supramolecular self-assembly on Au(111) using scanning tunneling microscopy (STM) through evaluating the island density variation as a function of substrate temperature and molecular deposition rate. We analyzed the experimental data using the classical nucleation theory and derived a molecular diffusion barrier of 0.68 ± 0.06 eV, a pyridyl-Cu bonding energy of 0.20 ± 0.09 eV, and a critical nucleus size of three. These results are confirmed by kinetic Monte Carlo (KMC) simulations. We also studied the postnucleation phenomena and revealed that below 373 K unstable islands (with sizes equal or smaller than the critical nucleus size) were formed upon the deposition and dissolved subsequently.

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Dimerization Boosts One-Dimensional Mobility of Conformationally Adapted Porphyrins on a Hexagonal Surface Atomic Lattice

Cited by 67 publications

References 50 publications

Visualization and thermodynamic encoding of single-molecule partition function projections

Visualization and thermodynamic encoding of single-molecule partition function projections

Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature

Combined scanning tunneling microscopy and kinetic Monte Carlo study on kinetics of Cu-coordinated pyridyl-porphyrin supramolecular self-assembly on a Au(111) surface

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