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42 results on '"Limburg, Bart"'

1. Charge-state dependent vibrational relaxation in a single-molecule junction

Author

Bian, Xinya, Chen, Zhixin, Sowa, Jakub K., Evangeli, Charalambos, Limburg, Bart, Swett, Jacob L., Baugh, Jonathan, Briggs, G. Andrew D., Anderson, Harry L., Mol, Jan A., and Thomas, James O.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Chemical Physics
Abstract

The interplay between nuclear and electronic degrees of freedom strongly influences molecular charge transport. Herein, we report on transport through a porphyrin dimer molecule, weakly coupled to graphene electrodes, that displays sequential tunneling within the Coulomb-blockade regime. The sequential transport is initiated by current-induced phonon absorption and proceeds by rapid sequential transport via a non-equilibrium vibrational distribution. We demonstrate this is possible only when the vibrational dissipation is slow relative to sequential tunneling rates, and obtain a lower bound for the vibrational relaxation time of 8 ns, a value that is dependent on the molecular charge state., Comment: 8 pages, 7 figures

Published
2022
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2. Single-electron transport in a molecular Hubbard dimer

Author

Thomas, James O., Sowa, Jakub K., Limburg, Bart, Bian, Xinya, Evangeli, Charalambos, Swett, Jacob L., Tewari, Sumit, Baugh, Jonathan, Schatz, George C., Briggs, G. Andrew D., Anderson, Harry L., and Mol, Jan A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Chemical Physics
Abstract

Many-body electron interactions are at the heart of chemistry and solid-state physics. Understanding these interactions is crucial for the development of molecular-scale quantum and nanoelectronic devices. Here, we investigate single-electron tunneling through an edge-fused porphyrin oligomer and demonstrate that its transport behavior is well described by the Hubbard dimer model. This allows us to study the role of electron-electron interactions in the transport setting. In particular, we empirically determine the molecule's on-site and inter-site electron-electron repulsion energies, which are in good agreement with density functional calculations, and establish the molecular electronic structure within various charge states. The gate-dependent rectification behavior is used to further confirm the selection rules and state degeneracies resulting from the Hubbard model. We therefore demonstrate that current flow through the molecule is governed by a non-trivial set of vibrationally coupled electronic transitions between various many-body states, and experimentally confirm the importance of electron-electron interactions in single-molecule devices., Comment: 19 pages, 5 figures

Published
2021
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3. Understanding resonant charge transport through weakly coupled single-molecule junctions

Author

Thomas, James O., Limburg, Bart, Sowa, Jakub K., Willick, Kyle, Baugh, Jonathan, Briggs, G. Andrew D., Gauger, Erik M., Anderson, Harry L., and Mol, Jan A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Chemical Physics
Abstract

Off-resonant charge transport through molecular junctions has been extensively studied since the advent of single-molecule electronics and it is now well understood within the framework of the non-interacting Landauer approach. Conversely, gaining a qualitative and quantitative understanding of the resonant transport regime has proven more elusive. Here, we study resonant charge transport through graphene-based zinc-porphyrin junctions. We experimentally demonstrate an inadequacy of the non-interacting Landauer theory as well as the conventional single-mode Franck-Condon model. Instead, we model the overall charge transport as a sequence of non-adiabatic electron transfers, the rates of which depend on both outer and inner-sphere vibrational interactions. We show that the transport properties of our molecular junctions are determined by a combination of electron-electron and electron-vibrational coupling, and are sensitive to the interactions with the wider local environment. Furthermore, we assess the importance of nuclear tunnelling and examine the suitability of semi-classical Marcus theory as a description of charge transport in molecular devices., Comment: version accepted in Nature Communications; SI available at https://researchportal.hw.ac.uk/en/publications/understanding-resonant-charge-transport-through-weakly-coupled-si

Published
2018
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16. Long-lived charged states of single porphyrin-tape junctions under ambient conditions

Author

Leary, Edmund, primary, Kastlunger, Georg, additional, Limburg, Bart, additional, Rincón-García, Laura, additional, Hurtado-Gallego, Juan, additional, González, M. Teresa, additional, Bollinger, Gabino Rubio, additional, Agrait, Nicolás, additional, Higgins, Simon J., additional, Anderson, Harry L., additional, Stadler, Robert, additional, and Nichols, Richard J., additional

Published
2021
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26. Unlocking the Potential of Substrate‐Directed CO2 Activation and Conversion: Pushing the Boundaries of Catalytic Cyclic Carbonate and Carbamate Formation.

Author

Limburg, Bart, Cristòfol, Àlex, Della Monica, Francesco, and Kleij, Arjan W.

Subjects
CARBON dioxide, INTERMEDIATE goods, CARBONATES, CATALYST structure, EPOXY compounds
Abstract

The unparalleled potential of substrate‐induced reactivity modes in the catalytic conversion of carbon dioxide and alcohol or amine functionalized epoxides is discussed in relation to more conventional epoxide/CO2 coupling strategies. This conceptually new approach allows for a substantial extension of the substitution degree and functionality of cyclic carbonate/carbamate products, which are predominant products in the area of nonreductive CO2 transformations. Apart from the creation of an advanced library of CO2‐based heterocyclic products and intermediates, also the underlying mechanistic reasons for this novel reactivity profile are debated with a prominent role for the design and structure of the involved catalysts. [ABSTRACT FROM AUTHOR]

Published
2020
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27. Anchor Groups for Graphene-Porphyrin Single-Molecule Transistors

Author

Limburg, Bart, primary, Thomas, James O., additional, Holloway, Gregory, additional, Sadeghi, Hatef, additional, Sangtarash, Sara, additional, Hou, Ian Cheng-Yi, additional, Cremers, Jonathan, additional, Narita, Akimitsu, additional, Müllen, Klaus, additional, Lambert, Colin J., additional, Briggs, G. Andrew D., additional, Mol, Jan A., additional, and Anderson, Harry L., additional

Published
2018
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28. Bias-Driven Conductance Increase with Length in Porphyrin Tapes

Author

Leary, Edmund, primary, Limburg, Bart, additional, Alanazy, Asma, additional, Sangtarash, Sara, additional, Grace, Iain, additional, Swada, Katsutoshi, additional, Esdaile, Louisa J., additional, Noori, Mohammed, additional, González, M. Teresa, additional, Rubio-Bollinger, Gabino, additional, Sadeghi, Hatef, additional, Hodgson, Andrew, additional, Agraı̈t, Nicolás, additional, Higgins, Simon J., additional, Lambert, Colin J., additional, Anderson, Harry L., additional, and Nichols, Richard J., additional

Published
2018
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29. Bias-driven conductance increase with length in porphyrin tapes

Author

Leary, Edmund, Limburg, Bart, Alanazy, Asma, Sangtarash, Sara, Grace, Iain, Swada, Katsutoshi, Esdaile, Louisa J., Noori, Mohammed, González, M. Teresa, Rubio-bollinger, Gabino, Sadeghi, Hatef, Hodgson, Andrew, Agraït, Nícolas, Higgins, Simon J., Lambert, Colin J., Anderson, Harry L., Nichols, Richard J., Leary, Edmund, Limburg, Bart, Alanazy, Asma, Sangtarash, Sara, Grace, Iain, Swada, Katsutoshi, Esdaile, Louisa J., Noori, Mohammed, González, M. Teresa, Rubio-bollinger, Gabino, Sadeghi, Hatef, Hodgson, Andrew, Agraït, Nícolas, Higgins, Simon J., Lambert, Colin J., Anderson, Harry L., and Nichols, Richard J.

Published
2018

30. Anchor Groups for Graphene-Porphyrin Single-Molecule Transistors

Author

Limburg, Bart, Thomas, James O., Holloway, Gregory, Sadeghi, Hatef, Sangtarash, Sara, Hou, Ian Cheng-yi, Cremers, Jonathan, Narita, Akimitsu, Müllen, Klaus, Lambert, Colin J., Briggs, G. Andrew D., Mol, Jan A., Anderson, Harry L., Limburg, Bart, Thomas, James O., Holloway, Gregory, Sadeghi, Hatef, Sangtarash, Sara, Hou, Ian Cheng-yi, Cremers, Jonathan, Narita, Akimitsu, Müllen, Klaus, Lambert, Colin J., Briggs, G. Andrew D., Mol, Jan A., and Anderson, Harry L.

Published
2018

33. Photocatalytic redox reactions at the surface of liposomes

Author

Limburg, Bart

Subjects
Water oxidation, Liposomes, Photocatalysis, Photosynthesis, Solar fuels
Abstract

Current energy-sources in the form of fossil fuels are quickly being depleted, while the demand of energy by society is increasing. In order to sustain this growth in energy demand, alternatives for the production of energy in a usable form are needed. One of such alternatives is to employ photocatalysis in order to use sunlight for the production of chemical fuels such as for example H2 or methanol. For the production of fuels, electrons are required that can be obtained by oxidizing water, as done by nature in a process called photosynthesis. The work in this thesis was inspired by this natural process; photosensitizers and water-oxidation catalysts were bound to lipid bilayers and their ability to photocatalytically oxidize water was studied in different conditions. The anchoring of compounds to a lipid bilayer leads to large differences in reactivity compared to homogeneous systems. In some cases, even the mechanism of the photocatalytic reaction changed upon membrane-anchoring of the constituents. In general, detailed experiments are described that fully characterize photocatalytic systems, because the mechanism of a reaction involving two different catalytic species is not straight-forward, and cannot be described by a single set of turn-over numbers.

Published
2015

35. Tetrahedral zinc in tetrakis(1-methyl-1H-imidazole-kappa N-3)zinc bis(tetrafluoridoborate)

Author

University of Helsinki, Department of Chemistry, University of Helsinki, Laboratory of Inorganic Chemistry (Dep. of Chemistry) (-2009), Reedijk, Jan, van Albada, Gerard A., Limburg, Bart, Mutikainen, Ilpo, Turpeinen, Urho, University of Helsinki, Department of Chemistry, University of Helsinki, Laboratory of Inorganic Chemistry (Dep. of Chemistry) (-2009), Reedijk, Jan, van Albada, Gerard A., Limburg, Bart, Mutikainen, Ilpo, and Turpeinen, Urho

Published
2012

40. Ruthenium-Decorated Lipid Vesicles: Light-Induced Release of [Ru(terpy)(bpy)(OH2)]2+ and Thermal Back Coordination.

Author

Bonnet, Sylvestre, Limburg, Bart, Meeldijk, Johannes D., Klein Gebbink, Robertus J. M., and Killian, J. Antoinette

Subjects
*RUTHENIUM, *ELECTROSTATICS, *IRRADIATION, *DRUG delivery systems, *SULFIDES
Abstract

Electrostatic forces play an important role in the interaction between large transition metal complexes and lipid bilayers. In this work, a thioether-cholestanol hybrid ligand (4) was synthesized, which coordinates to ruthenium(II) via its sulfur atom and intercalates into lipid bilayers via its apolar tail. By mixing its ruthenium complex [Ru(terpy)(bpy)(4)]2+ (terpy = 2,2′;6′,2″-terpyridine; bpy = 2,2′-bipyridine) with either the negatively charged lipid dimyristoylphosphatidylglycerol (DMPG) or with the zwitterionic lipid dimyristoylphosphatidylcholine (DMPC), large unilamellar vesicles decorated with ruthenium polypyridyl complexes are formed. Upon visible light irradiation the ruthenium-sulfur coordination bond is selectively broken, releasing the ruthenium fragment as the free aqua complex [Ru(terpy)(bpy)(OH2)]2+. The photochemical quantum yield under blue light irradiation (452 nm) is 0.0074(8) for DMPG vesicles and 0.0073(8) for DMPC vesicles (at 25 °C), which is not significantly different from similar homogeneous systems. Dynamic light scattering and cryo-TEM pictures show that the size and shape of the vesicles are not perturbed by light irradiation. Depending on the charge of the lipids, the cationic aqua complex either strongly interacts with the membrane (DMPG) or diffuses away from it (DMPC). Back coordination of [Ru(terpy)(bpy)(OH2)]2+ to the thioether-decorated vesicles takes place only at DMPG bilayers with high ligand concentrations (25 mol %) and elevated temperatures (70 °C). During this process, partial vesicle fusion was also observed. We discuss the potential of such ruthenium-decorated vesicles in the context of light-controlled molecular motion and light-triggered drug delivery. [ABSTRACT FROM AUTHOR]

Published
2011
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41. Ruthenium polypyridyl complexes hopping at anionic lipid bilayers through a supramolecular bond sensitive to visible light.

Author

Bahreman A, Limburg B, Siegler MA, Koning R, Koster AJ, and Bonnet S

Subjects
Crystallography, X-Ray, Ligands, Light, Molecular Structure, Photochemistry, Anions chemistry, Coordination Complexes chemistry, Lipid Bilayers chemistry, Pyridines chemistry, Ruthenium chemistry
Abstract

The new ruthenium complex [Ru(terpy)(dcbpy)(Hmte)](PF(6))(2) ([2](PF(6))(2); dcbpy=6,6'-dichloro-2,2'-bipyridine, terpy=2,2';6',2"-terpyridine, Hmte=2-(methylthio)ethanol) was synthesized. In the crystal structure, this complex is highly distorted, revealing steric congestion between dcbpy and Hmte. In water, [2](2+) forms spontaneously by reacting Hmte and the aqua complex [Ru(terpy)(dcbpy)(OH(2))](2+) ([1](2+)), with a second-order rate constant of 0.025 s(-1) M(-1) at 25 °C. In the dark, the Ru-S bond of [2](2+) is thermally unstable and partially hydrolyzes; in fact, [1](2+) and [2](2+) are in an equilibrium characterized by an equilibrium constant K of 151 M(-1). When exposed to visible light, the Ru-S bond is selectively broken to release [1](2+), that is, the equilibrium is shifted by visible-light irradiation. The light-induced equilibrium shifts were repeated four times without major signs of degradation; the Ru-S coordination bond in [2](2+) can be described as a robust, light-sensitive, supramolecular bond in water. To demonstrate the potential of this system in supramolecular chemistry, a new thioether-cholesterol conjugate (4), which inserts into lipid bilayers through its cholesterol moiety and coordinates to ruthenium through its sulfur atom, was synthesized. Thioether-functionalized, anionic, dimyristoylphosphatidylglycerol (DMPG), lipid vesicles, to which aqua complex [1](2+) efficiently coordinates, were prepared. Upon exposure of the Ru-decorated vesicles to visible light, the Ru-S bond is selectively broken, thus releasing [1](2+) that stays at the water-bilayer interface. When the light is switched off, the metal complex spontaneously coordinates back to the membrane-embedded thioether ligands without a need to heat the system. This process was repeated four times at 35 °C, thus achieving light-triggered hopping of the metal complex at the water-bilayer interface., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2012
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