liu.seSearch for publications in DiVA
Change search
Refine search result
12 1 - 50 of 55
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Ahsan, Aisha
    et al.
    Univ Basel, Switzerland.
    Mousavi, S. Fatemeh
    Univ Basel, Switzerland.
    Nijs, Thomas
    Univ Basel, Switzerland.
    Nowakowska, Sylwia
    Univ Basel, Switzerland.
    Popova, Olha
    Univ Basel, Switzerland.
    Wackerlin, Aneliia
    Univ Basel, Switzerland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Gade, Lutz H.
    Heidelberg Univ, Germany.
    Jung, Thomas A.
    Paul Scherrer Inst, Switzerland.
    Phase Transitions in Confinements: Controlling Solid to Fluid Transitions of Xenon Atoms in an On-Surface Network2019In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 15, no 3, article id 1803169Article in journal (Refereed)
    Abstract [en]

    This study reports on "phase" transitions of Xe condensates in on-surface confinements induced by temperature changes and local probe excitation. The pores of a metal-organic network occupied with 1 up to 9 Xe atoms are investigated in their propensity to undergo "condensed solid" to "confined fluid" transitions. Different transition temperatures are identified, which depend on the number of Xe atoms in the condensate and relate to the stability of the Xe clustering in the condensed "phase." This work reveals the feature-rich behavior of transitions of confined planar condensates, which provide a showcase toward future "phase-transition" storage media patterned by self-assembly. This work is also of fundamental interest as it paves the way to real space investigations of reversible solid to fluid transitions of magic cluster condensates in an array of extremely well-defined quantum confinements.

  • 2.
    Ahsan, Aisha
    et al.
    Univ Basel, Switzerland.
    Mousavi, S. Fatemeh
    Univ Basel, Switzerland.
    Nijs, Thomas
    Univ Basel, Switzerland.
    Nowakowska, Sylwia
    Univ Basel, Switzerland.
    Popova, Olha
    Univ Basel, Switzerland.
    Wackerlin, Aneliia
    Univ Basel, Switzerland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Gade, Lutz H.
    Heidelberg Univ, Germany.
    Jung, Thomas A.
    Univ Basel, Switzerland; Paul Scherrer Inst, Switzerland.
    Watching nanostructure growth: kinetically controlled diffusion and condensation of Xe in a surface metal organic network2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 11, p. 4895-4903Article in journal (Refereed)
    Abstract [en]

    Diffusion, nucleation and growth provide the fundamental access to control nanostructure growth. In this study, the temperature activated diffusion of Xe at and between different compartments of an on-surface metal organic coordination network on Cu(111) has been visualized in real space. Xe atoms adsorbed at lower energy sites become mobile with increased temperature and gradually populate energetically more favourable binding sites or remain in a delocalized fluid form confined to diffusion along a topological subset of the on-surface network. These diffusion pathways can be studied individually under kinetic control via the chosen thermal energy kT of the sample and are determined by the network and sample architecture. The spatial distribution of Xe in its different modes of mobility and the time scales of the motion is revealed by Scanning Tunneling Microscopy (STM) at variable temperatures up to 40 K and subsequent cooling to 4 K. The system provides insight into the diffusion of a van der Waals gas on a complex structured surface and its nucleation and coarsening/growth into larger condensates at elevated temperature under thermodynamic conditions.

  • 3.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Formation mechanisms of covalent nanostructures from density functional theory2016In: Proceedings of International Workshop on On-Surface Synthesis, Cham: Springer, 2016, p. 269-287Conference paper (Refereed)
    Abstract [en]

    In this chapter, it is demonstrated how electronic structure calculations, with focus on density functional theory, can be used to gain insight about on-surface reactions. I first give a brief introduction to how density functional theory can be used to study reactions. The focus is then shifted to two different types of on-surface reactions, highlighting the theoretical work that has been performed to gain detailed atomistic insight into them. First, the state of the art of the theory behind on-surface Ullmann coupling is described. In this reaction, molecular building blocks dehalogenate, which enables them to covalently couple. The most crucial reaction parameters are identified—the diffusion and coupling barriers of surface-supported radicals—and the potential for theory to optimize these is discussed. We then concentrate on the homo-coupling between terminal alkynes, a rudimentarily different process where molecules initially couple before undergoing a dehydrogenation step. The theory of the mechanism behind this coupling strategy is less developed than that of the on-surface Ullmann coupling, where fundamental questions remain to be unraveled. For example, by the subtle change of substrate from Ag to Au, the on-surface alkyne chemistry is completely altered from the homo-coupling to a cyclodehydrogenation reaction for the same molecular building block, of which origin remains unknown. The main objective of the chapter is to give an impression of what kind of information theory can obtain about reaction on surface, as well as to motivate and inspire for future theoretical studies, which will be needed to turn on-surface synthesis into a more predictive discipline.

  • 4.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Reaction mechanisms for on-surface synthesis of covalent nanostructures2016In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 28, no 8, p. 083002-Article, review/survey (Refereed)
    Abstract [en]

    In recent years, on-surface synthesis has become an increasingly popular strategy to form covalent nanostructures. The approach has great prospects for facilitating the manufacture of a range of fascinating materials with atomic precision. However, the on-surface reactions are enigmatic to control, currently restricting its bright perspectives and there is a great need to explore how the reactions are governed. The objective of this topical review is to summarize theoretical work that has focused on comprehending on-surface synthesis protocols through studies of reaction mechanisms.

  • 5.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Linköping University.
    Thermodynamics of an Electrocyclic Ring-Closure Reaction on Au(111)2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 38, p. 21716-21721Article in journal (Refereed)
    Abstract [en]

    We have computationally studied the effects of temperature on the reaction pathway of an electrocyclic ring-closure reaction on the Au(111) surface, particularly focusing on thermodynamic aspects of the reaction. The electrocyclic ring closure is accompanied by a series of dehydrogenation steps, and while it is found that temperature, in terms of vibrational entropy and enthalpy, has a reducing effect on most energy barriers, it does not alter the qualitative appreciation of the reaction kinetics. However, it is found that the way the abstracted hydrogen atoms are treated is crucial for the thermodynamics of the reaction. The overall reaction is highly endothermic but becomes thermodynamically favorable due to the entropy gain of the hydrogen byproducts, which desorb associatively from the surface as H2. The study provides new outlooks for the theoretical treatment of reactions related to on-surface synthesis, anticipated to be instructive for future studies.

  • 6.
    Björk, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Hanke, Felix
    Accelrys, 334 Science Park, Cambridge, CB4 0WN, United Kingdom.
    Towards Design Rules for Covalent Nanostructures on Metal Surfaces2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 4, p. 928-934Article in journal (Refereed)
    Abstract [en]

    The covalent molecular assembly on metal surfaces is explored, outlining the different types of applicable reactions. Density functional calculations for on-surface reactions are shown to yield valuable insights into specific reaction mechanisms and trends across the periodic table. Finally, it is shown how design rules could be derived for nanostructures on metal surfaces.

  • 7.
    Björk, Jonas
    et al.
    University of Liverpool, UK.
    Hanke, Felix
    University of Liverpool, UK.
    Palma, Carlos-Andres
    University de Strasbourg, France.
    Samorì, Paolo
    University de Strasbourg, France.
    Cecchini, Marco
    University de Strasbourg, France.
    Persson, Mats
    University of Liverpool, UK.
    Adsorption of Aromatic and Anti-Aromatic Systems on Graphene through π−π Stacking2010In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 1, p. 3407-3412Article in journal (Refereed)
    Abstract [en]

    The adsorption of neutral (poly)-aromatic, antiaromatic, and more generally π-conjugated systems on graphene is studied as a prototypical case of π-π stacking. To account for dispersive interactions, we compare the recent van der Waals density functional (vdw-DF) with three semiempirical corrections to density functional theory and two empirical force fields. The adsorption energies of the molecules binding to graphene predicted by the vdw-DFwere found to be in excellent agreement with temperature desorption experiments reported in litera- ture,whereas the results of theremaining functionals andforce fields only preserve the correct trends. The comparison of the dispersive versus electrostatic contribu- tions to the total binding energies in the aromatic and antiaromatic systems suggests that π-π interactions can be regarded as being prevalently dispersive in nature at large separations, whereas close to the equilibrium bonding distance, it is a complex interplay between dispersive and electrostatic Coulombic interactions. Moreover our results surprisingly indicate that the magnitude of π-π interactions normalized both per number of total atoms and carbon atoms increases signifi- cantly with the relative number of hydrogen atoms in the studied systems.

  • 8.
    Björk, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Hanke, Felix
    Surface Science Research Centre, University of Liverpool, UK.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Mechanisms of halogen-based covalent self-assembly on metal surfaces2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 15, p. 5768-5775Article in journal (Refereed)
    Abstract [en]

    We computationally study the reaction mechanisms of halogen-based covalent self-assembly, a major route for synthesizing molecular nanostructures and nanographenes on surfaces. Focusing on biphenyl as a small model system, we describe the dehalogenation, recombination, and diffusion processes. The kinetics of the different processes are also investigated, in particular how diffusion and coupling barriers affect recombination rates. Trends across the periodic table are derived from three commonly used close-packed (111) surfaces (Cu, Ag, and Au) and two halogens (Br and I). We show that the halogen atoms can poison the surface, thus hindering long-range ordering of the self-assembled structures. Finally, we present core-level shifts of the relevant carbon and halogen atoms, to provide reference data for reliably detecting self-assembly without the need for atomic-resolution scanning tunneling microscopy.

  • 9.
    Björk, Jonas
    et al.
    University of Liverpool, UK.
    Matena, Manfred
    University of Basel, Switzerland.
    Dyer, Matthew S.
    University of Liverpool, UK.
    Enache, Mihaela
    University of Basel, Switzerland.
    Lobo-Checa, Jorge
    University of Basel, Switzerland.
    Gade, Lutz H.
    University of Heidelberg, Germany.
    Jung, Thomas A.
    Paul-Scherrer-Institute, Villigen, Switzerland.
    Stöhr, Meike
    University of Basel, Switzerland.
    Persson, Mats
    University of Liverpool, UK.
    STM fingerprint of molecule-adatom interactions in a self-assembled metal-organic surface coordination network on Cu(111)2010In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 12, p. 8815-8821Article in journal (Refereed)
    Abstract [en]

    A novel approach of identifying metal atoms within a metal-organic surface coordination network using scanning tunnelling microscopy (STM) is presented. The Cu adatoms coordinated in the porous surface network of 1,3,8,10-tetraazaperopyrene (TAPP) molecules on a Cu(111) surface give rise to a characteristic electronic resonance in STM experiments. Using density functional theory calculations, we provide strong evidence that this resonance is a fingerprint of the interaction between the molecules and the Cu adatoms. We also show that the bonding of the Cu adatoms to the organic exodentate ligands is characterised by both the mixing of the nitrogen lone-pair orbitals of TAPP with states on the Cu adatoms and the partial filling of the lowest unoccupied molecular orbital (LUMO) of the TAPP molecule. Furthermore, the key interactions determining the surface unit cell of the network are discussed.

  • 10.
    Björk, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Adsorption of large hydrocarbons on coinage metals: a van der Waals density functional study2014In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 15, no 13, p. 2851-2858Article in journal (Refereed)
    Abstract [en]

    The adsorption of organic molecules onto the close-packed facets of coinage metals is studied, and how accurately adsorption heights can be described by using recent advances of the van der Waals density functional (vdWDF), with optPBE/vdWDF, optB86b/vdWDF, vdWDF2, and rev/vdWDF2 functionals is illustrated. The adsorption of two prototypical aromatic hydrocarbons is investigated, and the calculated adsorption heights are compared to experimental literature values from normal incident X-ray standing wave absorption and a state-of-the-art semi-empirical method. It is shown that both the optB86b/vdWDF and rev/vdWDF2 functionals describe adsorption heights with an accuracy of 0.1 Å, compared to experimental values, and are concluded as reliable methods of choice for related systems.

  • 11.
    Björk, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hanke, Felix
    University of Liverpool.
    Zipping Up: Cooperativity Drives the Synthesis of Graphene Nanoribbons2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 38, p. 14884-14887Article in journal (Refereed)
    Abstract [en]

    We investigate the cooperative effects controlling the synthesis of a graphene nanoribbon on the Au(111) surface starting from an anthracene polymer using density functional calculations including van der Waals interactions. We focus on the high-temperature cyclodehydrogenation step of the reaction and find that the reaction proceeds by simultaneously transferring two H-atoms from the anthracene units to the Au surface, leaving behind a C C bond in the process. This step is significantly more favorable than the three other potential reaction paths. Moreover, we find that successive dehydrogenations proceed from one end of the polyanthracene and propagate step-by-step through the polymer in a domino-like fashion.

  • 12.
    Björk, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Zhang, Yi-Qi
    Technische Universität München, Garching, Germany.
    Klappenberger, Florian
    Technische Universität München, Garching, Germany.
    Barth, Johannes V.
    Technische Universität München, Garching, Germany.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Unraveling the Mechanism of the Covalent Coupling Between Terminal Alkynes on a Noble Metal2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 6, p. 3181-3187Article in journal (Refereed)
    Abstract [en]

    The mechanism of the newly reported route for surface-assisted covalent coupling of terminal alkynes on Ag(111) is unraveled by density functional theory based transition state calculations. We illustrate that the reaction path is fundamentally different from the classical coupling schemes in wet chemistry. It is initiated by the covalent coupling between two molecules instead of single-molecule dehydrogenation. The silver substrate is found to play an important role stabilizing the intermediate species by chemical bonds, although it is hardly active electronically in the actual coupling step. The dimer intermediate is concluded to undergo two subsequent dehydrogenation processes expected to be rate-limiting according to the comparatively large barriers, which origin is discussed.

  • 13.
    Bronner, Christopher
    et al.
    Heidelberg Univ, Phys Chem Inst, D-69120 Heidelberg, Germany ; Free Univ Berlin, Fachbereich Phys, D-14195 Berlin, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Tegeder, Petra
    Heidelberg Univ, Phys Chem Inst, D-69120 Heidelberg, Germany ; Free Univ Berlin, Fachbereich Phys, D-14195 Berlin, Germany.
    Tracking and removing Br during the on-surface synthesis of a graphene nanoribbon2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 1, p. 486-493Article in journal (Refereed)
    Abstract [en]

    The fabrication of graphene nanoribbons (GNRs) requires a high degree of precision due to the sensitivity of the electronic structure on the edge shape. Using Br-substituted molecular precursors, this atomic precision can be achieved in a thermally induced two-step reaction following Br dissociation on a Au(111) surface. Using DFT, we find evidence that the Br atoms are bound to the intermediate polyanthrylene chains. We employ temperature-programmed desorption to demonstrate the associative desorption of HBr and molecular hydrogen during the final cyclodehydrogenation step of the reaction. Both processes are found to have similar activation barriers. Furthermore, we are able to remove Br atoms from the polyanthrylene chains by providing molecular hydrogen. The subsequent formation of GNR via a cyclodehydrogenation demonstrates that Br does not influence this part of the overall reaction.

  • 14.
    Cai, Liangliang
    et al.
    Tongji Univ, Peoples R China.
    Yu, Xin
    Tongji Univ, Peoples R China.
    Liu, Mengxi
    Natl Ctr Nanosci and Technol, Peoples R China.
    Sun, Qiang
    Tongji Univ, Peoples R China.
    Bao, Meiling
    Tongji Univ, Peoples R China.
    Zha, Zeqi
    Natl Ctr Nanosci and Technol, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Pan, Jinliang
    Natl Ctr Nanosci and Technol, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Ma, Honghong
    Tongji Univ, Peoples R China.
    Ju, Huanxin
    Univ Sci and Technol China, Peoples R China.
    Hu, Shanwei
    Univ Sci and Technol China, Peoples R China.
    Xu, Liang
    Tongji Univ, Peoples R China.
    Zou, Jiacheng
    Tongji Univ, Peoples R China.
    Yuan, Chunxue
    Tongji Univ, Peoples R China.
    Jacob, Timo
    Ulm Univ, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Zhu, Junfa
    Univ Sci and Technol China, Peoples R China.
    Qu, Xiaohui
    Natl Ctr Nanosci and Technol, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Xu, Wei
    Tongji Univ, Peoples R China.
    Direct Formation of C-C Double-Bonded Structural Motifs by On-Surface Dehalogenative Homocoupling of gem-Dibromomethyl Molecules2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 8, p. 7959-7966Article in journal (Refereed)
    Abstract [en]

    Conductive polymers are of great importance in a variety of chemistry-related disciplines and applications. The recently developed bottom-up on-surface synthesis strategy provides us with opportunities for the fabrication of various nanostructures in a flexible and facile manner, which could be investigated by high-resolution microscopic techniques in real space. Herein, we designed and synthesized molecular precursors functionalized with benzal gem-dibromomethyl groups. A combination of scanning tunneling microscopy, noncontact atomic force microscopy, high-resolution synchrotron radiation photoemission spectroscopy, and density functional theory calculations demonstrated that it is feasible to achieve the direct formation of C-C double-bonded structural motifs via on-surface dehalogenative homocoupling reactions on the Au(111) surface. Correspondingly, we convert the sp(3)-hybridized state to an sp(2)-hybridized state of carbon atoms, i.e., from an alkyl group to an alkenyl one. Moreover, by such a bottom-up strategy, we have successfully fabricated poly(phenylenevinylene) chains on the surface, which is anticipated to inspire further studies toward understanding the nature of conductive polymers at the atomic scale.

  • 15.
    Cirera, B.
    et al.
    IMDEA Nanosci, Spain.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Otero, R.
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain.
    Gallego, J. M.
    CSIC, Spain.
    Miranda, R.
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain.
    Ecija, D.
    IMDEA Nanosci, Spain.
    Efficient Lanthanide Catalyzed Debromination and Oligomeric Length-Controlled Ullmann Coupling of Aryl Halides2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 14, p. 8033-8041Article in journal (Refereed)
    Abstract [en]

    Lanthanide elements play a vital role in a broad range of high-tech applications, and there is an increasing interest in their catalytic activity, particularly in organo-metallics. However, their catalytic role on surfaces remains unexplored. Here, we present a scanning tunneling microscopy and density functional theory study of the debromination, contacting, and coupling of dibromine terphenyl species with Dy (f-block element) and Ag (d-block element) adatoms, respectively. We show that Dy debrominates the targeted species more efficiently than Ag adatoms at room temperature, promoting the formation of unprecedented C-Dy-C organo-metallic supramolecules versus C-Ag-C parallel chains for the Ag case. DFT calculations corroborate our results showing an almost spontaneous debromination process with Dy compared to Ag. Upon annealing, for samples containing Dy, the formation of C-Ag-C organometallic bonds and concomitant C-C coupling is inhibited, giving rise to a self-assembly of debrominated monomers, showing only a minority number of covalent dimes species. For samples without Dy covalent chains of irregular length are promoted. Our studies open new avenues for using lanthanide elements as efficient dehalogenation catalysts. Furthermore, we illustrate their potential as inhibitors of uncontrolled C-C coupling reactions, of great relevance for fine-tuning the length of polymeric compounds.

  • 16.
    Cirera, Borja
    et al.
    IMDEA Nanoscience, c/Faraday 9, Cantoblanco,Madrid, Spain.
    Giménez-Agulló, Nelson
    Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avinguda Pa¨ısos Catalans 16, Tarragona, Spain.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Martínez-Peña, Francisco
    IMDEA Nanoscience, c/Faraday 9, Cantoblanco,Madrid, Spain..
    Martin-Jimenez, Alberto
    IMDEA Nanoscience, c/Faraday 9, Cantoblanco,Madrid, Spain..
    Rodriguez-Fernandez, Jonathan
    Departamento de F´ısica de la Materia Condensada, Universidad Auto´noma de Madrid, c/Francisco Toma´s y Valiente.
    Pizarro, Ana M.
    IMDEA Nanoscience, c/Faraday 9, Cantoblanco,Madrid, Spain..
    Otero, Roberto
    IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain,Universidad Auto´noma de Madrid, c/Francisco Toma´s y Valiente.
    Gallego, José M.
    Instituto de Ciencia de Materiales de Madrid, c/ Sor Juana Ine´s de la Cruz 3, Cantoblanco,Madrid, Spain..
    Ballester, Pablo
    Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avinguda Pa¨ısos Catalans 16, Tarragona, Spain/Catalan Institutionfor Research and Advanced Studies, Passeig Lluis Companys 23, Barcelona, Spain..
    Galan-Mascaros, José R.
    Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avinguda Pa¨ısos Catalans 16, Tarragona, Spain/Catalan Institutionfor Research and Advanced Studies, Passeig Lluis Companys 23, Barcelona, Spain..
    Ecija, David
    IMDEA Nanoscience, c/Faraday 9, Cantoblanco, Madrid, Spain.
    Thermal selectivity of intermolecular versus intramolecular reactions on surfaces2016In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, no 11002Article in journal (Refereed)
    Abstract [en]

    On-surface synthesis is a promising strategy for engineering heteroatomic covalent nanoarchitectures with prospects in electronics, optoelectronics and photovoltaics. Here we report the thermal tunability of reaction pathways of a molecular precursor in order to select intramolecular versus intermolecular reactions, yielding monomeric or polymeric phthalocyanine derivatives, respectively. Deposition of tetra-aza-porphyrin species bearing ethyl termini on Au(111) held at room temperature results in a close-packed assembly. Upon annealing from room temperature to 275 °C, the molecular precursors undergo a series of covalent reactions via their ethyl termini, giving rise to phthalocyanine tapes. However, deposition of the tetra-aza-porphyrin derivatives on Au(111) held at 300 °C results in the formation and self-assembly of monomeric phthalocyanines. A systematic scanning tunnelling microscopy study of reaction intermediates, combined with density functional calculations, suggests a [2+2] cycloaddition as responsible for the initial linkage between molecular precursors, whereas the monomeric reaction is rationalized as an electrocyclic ring closure.

  • 17.
    Cirera, Borja
    et al.
    IMDEA Nanosci, Spain.
    Trukhina, Olga
    University of Autonoma Madrid, Spain.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Bottari, Giovanni
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain; University of Autonoma Madrid, Spain.
    Rodriguez-Fernandez, Jonathan
    University of Autonoma Madrid, Spain.
    Martin-Jimenez, Alberto
    IMDEA Nanosci, Spain.
    Islyaikin, Mikhail K.
    Ivanovo State University of Chemistry and Technology, Russia.
    Otero, Roberto
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain.
    Gallego, Jose M.
    CSIC, Spain.
    Miranda, Rodolfo
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain.
    Torres, Tomas
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain; University of Autonoma Madrid, Spain.
    Ecija, David
    IMDEA Nanosci, Spain.
    Long-Range Orientational Self-Assembly, Spatially Controlled Deprotonation, and Off-Centered Metalation of an Expanded Porphyrin2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 40, p. 14129-14136Article in journal (Refereed)
    Abstract [en]

    Expanded porphyrins are large-cavity macro cycles with enormous potential in coordination chemistry, anion sensing, photodynamic therapy, and optoelectronics. In the last two decades, the surface science community has assessed the physicochemical properties of tetrapyrrolic-like macrocydes. However, to date, the sublimation, self-assembly and atomistic insights of expanded porphyrins on surfaces have remained elusive. Here, we show the self-assembly on Au(111) of an expanded aza-porphyrin, namely, an "expanded hemi-spatially-controlled porphyrazine", through a unique growth mechanism based on deprotonation long-range orientational self-assembly. Furthermore, a spatially controlled "writing" protocol on such self-assembled architecture is presented based on the STM tip-induced deprotonation of the inner protons of individual macrocydes. Finally, the capability of these surface-confined macrocydes to host lanthanide elements is assessed, introducing a novel off-centered coordination motif. The presented findings represent a milestone in the fields of porphyrinoid chemistry and surface science, revealing a great potential for novel surface patterning, opening new avenues for molecular level information storage, and boosting the emerging field of surface-confined coordination chemistry involving f-block elements.

  • 18.
    Fritton, Massimo
    et al.
    Tech Univ Munich, Germany; Deutsch Museum, Germany.
    Duncan, David A.
    Tech Univ Munich, Germany; Diamond Light Source, England.
    Deimel, Peter S.
    Tech Univ Munich, Germany.
    Rastgoo-Lahrood, Atena
    Tech Univ Munich, Germany; Deutsch Museum, Germany.
    Allegretti, Francesco
    Tech Univ Munich, Germany.
    Barth, Johannes V.
    Tech Univ Munich, Germany.
    Heckl, Wolfgang M.
    Tech Univ Munich, Germany; Deutsch Museum, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lackinger, Markus
    Tech Univ Munich, Germany; Deutsch Museum, Germany.
    The Role of Kinetics versus Thermodynamics in Surface-Assisted Ullmann Coupling on Gold and Silver Surfaces2019In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 141, no 12, p. 4824-4832Article in journal (Refereed)
    Abstract [en]

    Surface-assisted Ullmann coupling is the workhorse of on-surface synthesis. Despite its obvious relevance, many fundamental and mechanistic aspects remain elusive. To shed light on individual reaction steps and their progression with temperature, temperature-programmed X-ray photoelectron spectroscopy (TP-XPS) experiments are performed for a prototypical model system. The activation of the coupling by initial dehalogenation is tracked by monitoring Br 3d core levels, whereas the C 1s signature is used to follow the emergence of metastable organometallic intermediates and their conversion to the final covalent products upon heating in real time. The employed 1,3,5-tris(4-bromophenyl)benzene precursor is comparatively studied on Ag(111) versus Au(111), whereby intermolecular bonds and network topologies are additionally characterized by scanning tunneling microscopy (STM). Besides the well-comprehended differences in activation temperatures for debromination, the thermal progression shows marked differences between the two surfaces. Debromination proceeds rapidly on Ag(111), but is relatively gradual on Au(111). While on Ag(111) debromination is well explained by first-order reaction kinetics, thermodynamics prevail on Au(111), underpinned by a close agreement between experimentally deduced and density functional theory (DFT) calculated reaction enthalpies. Thermodynamically controlled debromination on Au(111) over a large temperature range implies an unexpectedly long lifetime of surface-stabilized radicals prior to covalent coupling, as corroborated by TP-XPS of C is core levels. These insights are anticipated to play an important role regarding our ability to rationally synthesize atomically precise low-dimensional covalent nanostructures on surfaces.

  • 19.
    Fritton, Massimo
    et al.
    Deutsch Museum, Germany; Tech Univ Munich, Germany.
    Otte, Katrin
    Bavarian Acad Sci and Humanities, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Biswas, Pronay Kumar
    Univ Siegen, Germany.
    Heckl, Wolfgang M.
    Deutsch Museum, Germany; Tech Univ Munich, Germany.
    Schmittel, Michael
    Univ Siegen, Germany.
    Lackinger, Markus
    Deutsch Museum, Germany; Tech Univ Munich, Germany.
    The influence of ortho-methyl substitution in organometallic self-assembly - a comparative study on Cu(111) vs. Ag(111)2018In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 70, p. 9745-9748Article in journal (Refereed)
    Abstract [en]

    Metal surface-induced dehalogenation of precursors is known to initiate self-assembly of organometallic networks, where tectons are connected via carbon-metal-carbon (C-M-C) bonds. Even though reversibility of the C-M-C bonds facilitates structural equilibration, defects associated with highly bent organometallic linkages are still commonly observed. By introducing a steric hindrance to reduce the C-M-C bond angle flexibility, we find well ordered organometallic networks of an ortho-methyl substituted 1,3,5-tris(p-bromophenyl)-benzene analogue on Cu(111) after room-temperature (RT) deposition and on Ag(111) after annealing.

  • 20.
    Gottardi, Stefano
    et al.
    University of Groningen, Netherlands.
    Muller, Kathrin
    University of Groningen, Netherlands.
    Bignardi, Luca
    University of Groningen, Netherlands.
    Carlos Moreno-Lopez, Juan
    University of Groningen, Netherlands.
    Tuan Anh Pham; Ivashenko, Oleksii
    University of Groningen, Netherlands.
    Yablonskikh, Mikhail
    Sincrotrone Trieste Scpa, Italy.
    Barinov, Alexei
    Sincrotrone Trieste Scpa, Italy.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Rudolf, Petra
    University of Groningen, Netherlands.
    Stohr, Meike
    University of Groningen, Netherlands.
    Comparing Graphene Growth on Cu(111) versus Oxidized Cu(111)2015In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, no 2, p. 917-922Article in journal (Refereed)
    Abstract [en]

    The epitaxial growth of graphene on catalytically active metallic surfaces via chemical vapor deposition (CVD) is known to be one of the most reliable routes toward high-quality large-area graphene. This CVD-grown graphene is generally coupled to its metallic support resulting in a modification of its intrinsic properties. Growth on oxides is a promising alternative that might lead to a decoupled graphene layer. Here, we compare graphene on a pure metallic to graphene on an oxidized copper surface in both cases grown by a single step CVD process under similar conditions. Remarkably, the growth on copper oxide, a high-k dielectric material, preserves the intrinsic properties of graphene; it is not doped and a linear dispersion is observed close to the Fermi energy. Density functional theory calculations give additional insight into the reaction processes and help explaining the catalytic activity of the copper oxide surface.

  • 21.
    Hanke, Felix
    et al.
    Surface Science Research Centre, University of Liverpool, UK.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Structure and local reactivity of the Au(111) surface reconstruction2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 23Article in journal (Refereed)
    Abstract [en]

    The close-packed (111) surface of gold is well known to show a 22×√3 reconstruction on single nm lengths with a long-range herringbone pattern on scales of a few hundred nm. Here we investigate the local reconstruction using density functional theory and compare the results to scanning tunneling microscopy experiments. Moreover, we use hydrogen and fluorine as probe atoms to investigate changes in the ability of the Au(111) surface to catalyze the reactions involved in the formation of molecular nanostructures. We find a small variation of the reactivity across different surface sites and link those results to the local coordination environment of the face-centered-cubic (fcc), hexagonal-close-packed (hcp), and ridge regions. Finally, we scrutinize a commonly used approximation in density functional studies, namely that Au(111) is atomically flat and a perfect termination of the fcc lattice.

  • 22.
    Hanke, Felix
    et al.
    Surface Science Research Centre, University of Liverpool, UK.
    Dyer, Matthew S.
    Surface Science Research Centre, University of Liverpool, UK.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Persson, Mats
    Surface Science Research Centre, University of Liverpool, UK.
    Structure and stability of weakly chemisorbed ethene adsorbed on low-index Cu surfaces: performance of density functionals with van der Waals interactions2012In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 42, p. 424217-424225Article in journal (Refereed)
    Abstract [en]

    We have investigated the performance of popular density functionals that include van der Waals interactions for the experimentally well-characterized problem of ethene (C(2)H(4)) adsorbed on the low-index surfaces of copper. This set of functionals does not only include three van der Waals density functionals-vdwDF-PBE, vdwDF-revPBE and optB86b-vdwDF-and two dispersion-corrected functionals-Grimme and TS-but also local and semi-local functionals such as LDA and PBE. The adsorption system of ethene on copper was chosen because it is a weakly chemisorbed system for which the vdW interactions are expected to give a significant contribution to the adsorption energy. Overall the density functionals that include vdW interactions increased substantially the adsorption energies compared to the PBE density functional but predicted the same adsorption sites and very similar C-C bonding distances except for two of the van der Waals functionals. The top adsorption site was predicted almost exclusively for all functionals on the (110), (100) and (111) surfaces, which is in agreement with experiment for the (110) surface but not for the (100) surface. On the (100) surface, all functionals except two van der Waals density functionals singled out the observed cross-hollow site from the calculated C-C bonding distances and adsorption heights. On the top sites on the (110) surface and the cross-hollow site on the Cu(100) surface, the ethene molecule was found to form a weak chemisorption bond. On the (111) surface, all functionals gave a C-C bonding distance and an adsorption height more typical for physisorption, in agreement with experiments.

  • 23.
    Hellwig, Raphael
    et al.
    Tech Univ Munich, Germany.
    Uphoff, Martin
    Tech Univ Munich, Germany.
    Paintner, Tobias
    Tech Univ Munich, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ruben, Mario
    KIT, Sweden; Univ Strasbourg, France.
    Klappenberger, Florian
    Tech Univ Munich, Germany.
    Barth, Johannes V.
    Tech Univ Munich, Germany.
    Ho-Mediated Alkyne Reactions at Low Temperatures on Ag(111)2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 60, p. 16126-16135Article in journal (Refereed)
    Abstract [en]

    Low-temperature approaches to catalytic conversions promise efficiency, selectivity, and sustainable processes. Control over certain coupling reactions can be obtained via the pre-positioning of reactive moieties by self-assembly. However, in the striving field of on-surface synthesis atomistic precision and control remains largely elusive, because the employed coupling reactions proceed at temperatures beyond the thermal stability of the supramolecular templates. Here, utilizing scanning tunneling microscopy, we demonstrate terminal alkyne on-surface reactions mediated by Ho atoms at a weakly reactive Ag(111) substrate at lowtemperatures. Density functional theory calculations confirm the catalytic activity of the involved adatoms. Pre-deposited Ho induces alkyne dehydrogenation starting at substrate temperatures as low as 100 K. Ho arriving at molecularly pre-covered surfaces held at 130 and 200 K produces covalent enyne-linked dimers and initiates cyclotrimerization, respectively. Statistical product analysis indicates a two-step pathway for the latter, whereby the enyne intermediates influence the distribution of the products. High chemoselectivity results from the absence of cyclotetramerization and diyne-forming homocoupling. Our analysis indicates that mainly the arriving Ho adatoms enable the coupling. These findings support the concept of dynamic heterogeneity by single-atom catalysts and pave the way for alternative means to control on-surface reactions.

  • 24.
    Honkela, Maija
    et al.
    Aalto University, Finland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Persson, Mats
    Surface Science Research Centre, University of Liverpool, UK.
    Computational study of the adsorption and dissociation of phenol on Pt and Rh surfaces2012In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, no 16, p. 5849-5854Article in journal (Refereed)
    Abstract [en]

    The adsorption of phenol on flat and stepped Pt and Rh surfaces and the dissociation of hydrogen from the hydroxyl group of phenol on Pt(111) and Rh(111) were studied by density functional calculations. On both Pt(111) and Rh(111), phenol adsorbs with the aromatic ring parallel to the surface and the hydroxyl group tilted away from the surface. Furthermore, adsorption on stepped surfaces was concluded to be unfavourable compared to the (111) surfaces due to the repulsion of the hydroxyl group from the step edges. Transition state calculations revealed that the reaction barriers, associated with the dissociation of phenol into phenoxy, are almost identical on Pt and Rh. Furthermore, the oxygen in the dissociated phenol is strongly attracted by Rh(111), while it is repelled by Pt(111).

  • 25.
    Kawai, Shigeki
    et al.
    Namiki, Tsukuba, 305-0044 Ibaraki, Japan/Basel, Switzerland/ Honcho, Kawaguchi, 332-0012 Saitama, Japan.
    Foster, Adam S.
    Aalto University, Finland/Kanazawa University, Kanazawa Japan..
    Björkman, Torbjörn
    Aalto University/Åbo Akademi University, Finland..
    Nowakowska, Sylwia
    University of Basel,Switzerland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Canova, Filippo Federici
    Aalto University, Finland.
    Gade, Lutz H.
    Universität Heidelberg, Germany.
    Jung, Thomas A.
    University of Basel, Switzerland/Paul Scherrer Institute, Switzerland..
    Meyer, Ernst
    University of Basel, Switzerland..
    Van der Waals interactions and the limits of isolated atom models at interfaces2016In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, article id 11559Article in journal (Refereed)
    Abstract [en]

    Van der Waals forces are among the weakest, yet most decisive interactions governing condensation and aggregation processes and the phase behaviour of atomic and molecular matter. Understanding the resulting structural motifs and patterns has become increasingly important in studies of the nanoscale regime. Here we measure the paradigmatic van der Waals interactions represented by the noble gas atom pairs Ar–Xe, Kr–Xe and Xe–Xe with a Xe-functionalized tip of an atomic force microscope at low temperature. Individual rare gas atoms were fixed at node sites of a surface-confined two-dimensional metal–organic framework. We found that the magnitude of the measured force increased with the atomic radius, yet detailed simulation by density functional theory revealed that the adsorption induced charge redistribution strengthened the van der Waals forces by a factor of up to two, thus demonstrating the limits of a purely atomic description of the interaction in these representative systems.

  • 26.
    Kepčija, Nenad
    et al.
    Technische Universität München, Germany.
    Zhang, Yi-Qi
    Technische Universität München, Germany.
    Kleinschrodt, Martin
    Technische Universität München, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Klyatskaya, Svetlana
    Karlsruhe Institute of Technology, Germany.
    Klappenberger, Florian
    Technische Universität München, Germany.
    Ruben, Mario
    Karlsruhe Institute of Technology, Germany.
    Barth, Johannes V.
    Technische Universität München, Germany.
    Steering On-Surface Self-Assembly of High-Quality Hydrocarbon Networks with Terminal Alkynes2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 8, p. 3987-3995Article in journal (Refereed)
    Abstract [en]

    The two-dimensional (2D) self-assembly of 1,3,5-triethynyl-benzene (TEB) and de novo synthesized 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB) on Ag(111) was investigated by means of scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV) conditions. Both 3-fold symmetric molecules form long-range ordered nanoporous networks featuring organizational chirality, mediated by novel, planar 6-fold cyclic binding motifs. The key interaction for the expression of the motifs is identified as C–H···π bonding. For Ext-TEB, an additional open-porous phase exists with the 3-fold motif. The nature of the underlying noncovalent bonding schemes is thoroughly analyzed by density functional theory (DFT) calculations including van der Waals corrections. The comparison of calculations focusing on isolated 2D molecular sheets and those including the substrate reveals the delicate balance between the attractive molecule–molecule interaction, mediated by both the terminal alkyne and the phenyl groups, and the molecule–substrate interaction responsible for the commensurability and the regularity of the networks. Comparison with bulk structures of similar molecules suggests that these strictly planar cyclic binding motifs appear only in 2D environments.

  • 27.
    Klappenberger, Florian
    et al.
    Technical University of Munich, Germany.
    Zhang, Yi-Qi
    Technical University of Munich, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Klyatskaya, Svetlana
    Karlsruhe Institute Technology, Germany.
    Ruben, Mario
    Karlsruhe Institute Technology, Germany; University of Strasbourg, France.
    Barth, Johannes V.
    Technical University of Munich, Germany.
    On-Surface Synthesis of Carbon-Based Scaffolds and Nanomaterials Using Terminal Alkynes2015In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 48, no 7, p. 2140-2150Article, review/survey (Refereed)
    Abstract [en]

    CONSPECTUS: The covalent linking of acetylene compounds is an important synthetic tool to control carbon carbon bond formation and has been extensively studied for more than a century. Notably, Glaser coupling and subsequently developed refined procedures present an important route for the fabrication of distinct carbon-based scaffolds incorporating units with both sp(2)- and sp-hybridizations, such as carbyne chains, or two-dimensional (2D) graphyne or graphdiyne networks. However, the realization of the envisioned regular low-dimensional compounds and nanoarchitectures poses formidable challenges when following conventional synthesis protocols in solution, which we briefly overview. Now, recent developments in on-surface synthesis establish novel means for the construction of tailored covalent nanostructures under ultrahigh vacuum conditions. Here we focus on the exploration of pathways utilizing interfacial synthesis with terminal alkynes toward the atomically precise fabrication of low-dimensional carbon-rich scaffolds and nanomaterials. We review direct, molecular-level investigations, mainly relying on scanning probe microscopy, providing atomistic insights into thermally activated reaction schemes, their special pathways and products. Using custom-made molecular units, the employed homocoupling, cyclotrimerization, cycloaddition, and radical cyclization processes indeed yield distinct compounds, extended oligomers or 2D networks. Detailed insights into surface interactions such as bonding sites or conformational adaptation, and specific reaction mechanisms, including hierarchic pathways, were gained by sophisticated density functional theory calculations, complemented by X-ray spectroscopy measurements. For the fabrication of regular nanostructures and architectures, it is moreover imperative to cope with spurious side reactions, frequently resulting in chemical diversity. Accordingly, we highlight measures for increasing chemo- and regioselectivity by smart precursor design, substrate templating, and external stimuli. The ensuing preorganization of functional groups and control of side reactions increases product yields markedly. Finally, the electronic band structures of selected cases of novel low-dimensional hydrocarbon materials accessible with the monomers employed to date are discussed with a specific focus on their differences to theoretically established graphyne- and graphdiyne-related scaffolds. The presented methodology and gained insights herald further advancements in the field, heading toward novel molecular compounds, low-dimensional nanostructures, and coherently reticulated polymeric layers, eventually presenting well-defined arrangements with specific carbon carbon bond sequencing and electronic characteristics. The functional properties of these or other foreseeable scaffolds and architectures bear significant prospects for a wide range of applications, for example, in nanoelectronics, photonics, or carbon-based technologies.

  • 28.
    Li, Qing
    et al.
    Soochow Univ, Peoples R China.
    Yang, Biao
    Soochow Univ, Peoples R China.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Zhong, Qigang
    Soochow Univ, Peoples R China; Justus Liebig Univ Giessen, Germany.
    Ju, Huanxin
    Univ Sci and Technol China, Peoples R China.
    Zhang, Junjie
    Soochow Univ, Peoples R China.
    Cao, Nan
    Soochow Univ, Peoples R China.
    Shi, Ziliang
    Soochow Univ, Peoples R China.
    Zhang, Haiming
    Soochow Univ, Peoples R China.
    Ebeling, Daniel
    Justus Liebig Univ Giessen, Germany.
    Schirmeisen, Andre
    Justus Liebig Univ Giessen, Germany.
    Zhu, Junfa
    Univ Sci and Technol China, Peoples R China.
    Chi, Lifeng
    Soochow Univ, Peoples R China.
    Hierarchical Dehydrogenation Reactions on a Copper Surface2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 19, p. 6076-6082Article in journal (Refereed)
    Abstract [en]

    Hierarchical control of chemical reactions is being considered as one of the most ambitious and challenging topics in modern organic chemistry. In this study, we have realized the one-by-one scission of the X-H bonds (X = N and C) of aromatic amines in a controlled fashion on the Cu(lll) surface. Each dehydrogenation reaction leads to certain metal-organic supramolecular structures, which were monitored in single-bond resolution via scanning tunneling microscopy and noncontact atomic force microscopy. Moreover, the reaction pathways were elucidated from X-ray photoelectron spectroscopy measurements and density functional theory calculations. Our insights pave the way for connecting molecules into complex structures in a more reliable and predictable manner, utilizing carefully tuned stepwise on-surface synthesis protocols.

  • 29.
    Lin, Tao
    et al.
    Technical University of Munich, Germany.
    Zhang, Liding
    Technical University of Munich, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Chen, Zhi
    Karlsruhe Institute Technology, Germany.
    Ruben, Mario
    Karlsruhe Institute Technology, Germany; University of Strasbourg, France.
    Barth, Johannes V.
    Technical University of Munich, Germany.
    Klappenberger, Florian
    Technical University of Munich, Germany.
    Terminal Alkyne Coupling on a Corrugated Noble Metal Surface: From Controlled Precursor Alignment to Selective Reactions2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 62, p. 15588-15593Article in journal (Refereed)
    Abstract [en]

    Surface-templated covalent coupling of organic precursors currently emerges as a promising route to the atom-precise fabrication of low-dimensional carbon materials. Here, we investigate the adsorption and the coupling reactions of 4,4-diethynyl-1,1:4,1-terphenyl on Au(110) under ultra-high vacuum conditions by using scanning tunneling microscopy combined with density functional theory and kinetic Monte Carlo calculations. Temperature treatment induces both 1,2,4-asymmetric cyclotrimerization and homocoupling, resulting in various reaction products, including a previously unreported, surface-templated H-shaped pentamer. Our analysis of the temperature-dependent relative product abundances unravels that 1,2,4-trimerization and homocoupling proceed via identical intermediate species with the final products depending on the competition of coupling to a third monomer versus dehydrogenation. Our study sheds light on the control of coupling reactions by corrugated surfaces and annealing protocols.

  • 30.
    Lischka, Matthias
    et al.
    Tech Univ Munich, Germany; Deutsch Museum, Germany.
    Fritton, Massimo
    Tech Univ Munich, Germany; Deutsch Museum, Germany.
    Eichhorn, Johanna
    Tech Univ Munich, Germany; Deutsch Museum, Germany.
    Vyas, Vijay S.
    Max Planck Inst Solid State Res, Germany; Marquette Univ, WI 53233 USA.
    Strunskus, Thomas
    Christian Albrechts Univ Kiel, Germany.
    Lotsch, Bettina V.
    Max Planck Inst Solid State Res, Germany; Nanosyst Initiat Munich, Germany; Ctr NanoSci, Germany; Univ Munich LMU, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Heckl, Wolfgang M.
    Tech Univ Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Ctr NanoSci, Germany.
    Lackinger, Markus
    Tech Univ Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Ctr NanoSci, Germany.
    On-Surface Polymerization of 1,6-Dibromo-3,8-diiodpyrene-A Comparative Study on Au(111) Versus Ag(111) by STM, XPS, and NEXAFS2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 11, p. 5967-5977Article in journal (Refereed)
    Abstract [en]

    The surface chemistry of 1,6-dibromo-3,8-diiodopyrene (Br2I2Py) is comparatively studied on Au(111) versus Ag(111) surfaces under ultrahigh vacuum conditions by a combination of high-resolution scanning tunneling microscopy (STM) and X-ray spectroscopy. The chemical state of the molecular networks, that is, the dehalogenation and the possible formation of organometallic intermediates, is assessed by X-ray photoelectron spectroscopy. In addition, pyrene tilt angles are quantified by carbon K-edge near edge X-ray absorption fine structure experiments. Upon room-temperature (RT) deposition of Br2I2Py onto Au(111), only partial deiodination was found, and STM revealed the coexistence of ordered arrangements of both intact Br2I2Py molecules and organometallic dimers as well as few larger aggregates. Further annealing to 100 C triggered full deiodination followed by the formation of organometallic chains of otherwise still brominated molecules. By contrast, on Ag(111), iodine is fully and bromine is partly dissociated upon RT deposition of Br2I2Py. The initially disordered organometallic aggregates can be reorganized into more ordered structures by mild annealing at 125 degrees C. Yet, the conversion of the organometallic intermediates into well-defined cross-linked quasi 2D covalent networks was neither possible on Au(111) nor on Ag(111). This is attributed to the large steric hindrance in the covalently linked adsorbed state.

  • 31.
    Matena, Manfred
    et al.
    Department of Physics, University of Basel, Basel, Switzerland, Donostia International Physics Center, San Sebastian, Spain .
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology. Surface Science Research Centre, Department of Chemistry, University of Liverpool, Liverpool, United Kingdom.
    Wahl, Markus
    Department of Physics, University of Basel, Basel, Switzerland.
    Lee, Tien-Lin
    European Synchrotron Radiation Facility, Grenoble, France.
    Zegenhagen, Jörg
    European Synchrotron Radiation Facility, Grenoble, France.
    Gade, Lutz H.
    Anorganisch-Chemisches Institut, Universität Heidelberg, Heidelberg, Germany.
    Jung, Thomas A.
    Department of Physics, University of Basel, Basel, Switzerland, Laboratory for Micro- and Nanotechnology, Villigen, Switzerland.
    Persson, Mats
    Surface Science Research Centre, University of Liverpool, UK, Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Stöhr, Meike
    Department of Physics, University of Basel, Basel, Switzerland, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
    On-surface synthesis of a two-dimensional porous coordination network: Unraveling adsorbate interactions2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, p. 125408-125415Article in journal (Refereed)
    Abstract [en]

    We present a detailed experimental and theoretical characterization of the adsorption of the perylene derivative 4,9-diaminoperylene-quinone-3,10-diimine (DPDI) on Cu(111) and compare it to its threefold dehydrogenated derivative 3deh-DPDI, which forms in a surface reaction upon annealing. While DPDI itself does not give rise to long-range ordered structures due to lack of appropriate functional groups, 3deh-DPDI acts as an exoligand in a Cu-coordinated honeycomb network on Cu(111). The main focus of this work lies on the analysis of intermolecular and molecule-substrate interactions by combining results from scanning tunneling microscopy, x-ray photoelectron spectroscopy, x-ray standing wave measurements, and density functional theory. We show, in particular, that the interactions between metal atoms and organic ligands effectively weaken the molecule-surface interactions for 3deh-DPDI leading to an increase in molecule-substrate distances compared to the DPDI precursor. Our experimental findings also shed light on the applicability of current theories, namely van der Waals corrections to density functional theory.

  • 32.
    Matena, Manfred
    et al.
    University of Basel, Switzerland.
    Stöhr, Meike
    University of Basel, Switzerland.
    Riehm, Till
    University of Heidelberg, Germany.
    Björk, Jonas
    University of Liverpool, UK.
    Martens, Susanne
    University of Heidelberg, Germany.
    Dyer, Matthew S.
    University of Liverpool, UK.
    Persson, Mats
    University of Liverpool, UK.
    Lobo-Checa, Jorge
    University of Basel, Switzerland.
    Müller, Kathrin
    Paul-Scherrer-Institute, Villigen, Switzerland.
    Enache, Mihaela
    University of Basel, Switzerland.
    Wadepohl, Hubert
    University of Heidelberg, Germany.
    Zegenhagen, Jörg
    European Synchrotron Radiation Facility, Grenoble, France.
    Jung, Thomas A.
    Paul-Scherrer-Institute, Villigen, Switzerland.
    Gade, Lutz H.
    University of Heidelberg, Germany.
    Aggregation and contingent metal/surface reactivity of 1,3,8,10-tetraazaperopyrene (TAPP) on Cu(111)2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 7, p. 2079-2091Article in journal (Refereed)
    Abstract [en]

    The structural chemistry and reactivity of 1,3,8,10-tetraazaperopyrene (TAPP) on Cu(111) under ultra-high-vacuum (UHV) conditions has been studied by a combination of experimental techniques (scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy, XPS) and DFT calculations. Depending on the deposition conditions, TAPP forms three main assemblies, which result from initial submonolayer coverages based on different intermolecular interactions: a close-packed assembly similar to a projection of the bulk structure of TAPP, in which the molecules interact mainly through van der Waals (vDW) forces and weak hydrogen bonds; a porous copper surface coordination network; and covalently linked molecular chains. The Cu substrate is of crucial importance in determining the structures of the aggregates and available reaction channels on the surface, both in the formation of the porous network for which it provides the Cu atoms for surface metal coordination and in the covalent coupling of the TAPP molecules at elevated temperature. Apart from their role in the kinetics of surface transformations, the available metal adatoms may also profoundly influence the thermodynamics of transformations by coordination to the reaction product, as shown in this work for the case of the Cu-decorated covalent poly(TAPP-Cu) chains.

  • 33.
    Medeiros, Paulo V. C.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Müller, Kathrin
    Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.
    Jung, Thomas A.
    Laboratory for Micro- and Nanotechnology, Paul-Scherrer-Institute, Switzerland.
    Gade, Lutz H.
    Anorganisch-Chemisches Institut, Universität Heidelberg, Germany.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Stöhr, Meike
    Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.
    Self-assembly of a DPDI+PTCDA mixed layer on Ag(111): Theory and experimentsManuscript (preprint) (Other academic)
    Abstract [en]

    We present a combined experimental and theoretical investigation of the self-assembly of a binary mixture of 4,9-diaminoperylene-quinone-3,10-diimine (DPDI) and 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) molecules on Ag(111). At a 1:1 ratio, the two molecules intermix to form a long-range ordered bimolecular network stabilized by intermolecular hydrogen bonding. We show, by means of low energy electron diffraction (LEED) measurements, that the self-assembled network is commensurate with the underlying silver surface. Scanning tunneling microscope (STM) measurements and density functional theory (DFT) calculations are combined to unravel the structural configuration of the system. Core-level binding energy shifts for the 1s levels of the O atoms, obtained from both X-ray photoelectron spectroscopy (XPS) measurements and DFT simulations, are reported and compared. Our DFT calculations allow the investigation of the interplay between molecule-molecule and molecule-surface interactions in the network. Our combined experimental-theoretical approach allows a precise characterization of the structural and electronic properties of the studied system.

  • 34.
    Medeiros, Paulo V. C.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Effects of extrinsic and intrinsic perturbations on the electronic structure of graphene: Retaining an effective primitive cell band structure by band unfolding2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 4, p. 041407-1-041407-4Article in journal (Refereed)
    Abstract [en]

    We use a band unfolding technique to recover an effective primitive cell picture of the band structure of graphene under the influence of different types of perturbations. This involves intrinsic perturbations, such as structural defects, and external ones, comprising nitrogen substitutions and the inclusion of graphene in adsorbed systems. In such cases, the band unfolding provides a reliable and efficient tool for quantitatively analyzing the effect of doping and defects on the electronic structure of graphene. We envision that this approach will become a standard method in the computational analysis of graphene's electronic structure in related systems.

  • 35.
    Medeiros, Paulo Vinicius Da Costa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Tsirpin, Stepan S.
    DIPC, San Sebastian 20018, Basque Country, Spain; Tomsk State Univ, Tomsk 634050, Russia; St Petersburg State Univ, St Petersburg 198504, Russia .
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Unfolding spinor wave functions and expectation values of general operators: Introducing the unfolding-density operator2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, p. 041116(R)-041120(R)Article in journal (Refereed)
    Abstract [en]

    We show that the spectral weights W mK ⃗ (k ⃗ ) used for the unfolding of two-component spinor eigenstates ∣ ∣ ψ SC mK ⃗ ⟩=|α⟩|ψ SC mK ⃗ ,α⟩+|β⟩|ψ SC mK ⃗ ,β⟩ can be decomposed as the sum of the partial spectral weights W μ mK ⃗ (k ⃗ ) calculated for each component μ=α,β independently, effortlessly turning a possibly complicated problem involving two coupled quantities into two independent problems of easy solution. Furthermore, we define the unfolding-density operator ρ ˆ K ⃗ (k ⃗ ;ɛ) , which unfolds the primitive cell expectation values φ pc (k ⃗ ;ɛ) of any arbitrary operator φ ˆ according to φ pc (k ⃗ ;ɛ)=Tr(ρ ˆ K ⃗ (k ⃗ ;ɛ)φ ˆ ) . As a proof of concept, we apply the method to obtain the unfolded band structures, as well as the expectation values of the Pauli spin matrices, for prototypical physical systems described by two-component spinor eigenfunctions.

  • 36.
    Morchutt, Claudius
    et al.
    Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany Ecole Polytech Fed Lausanne, Inst Phys Mat Condensee, CH-1015 Lausanne, Switzerland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Krotzky, Sören
    Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany.
    Gutzler, Rico
    Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany.
    Kern, Klaus
    Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany Ecole Polytech Fed Lausanne, Inst Phys Mat Condensee, CH-1015 Lausanne, Switzerland.
    Covalent coupling via dehalogenation on Ni(111) supported boron nitride and graphene2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 12, p. 2440-2443Article in journal (Refereed)
    Abstract [en]

    Polymerization of 1,3,5-tris(4-bromophenyl)benzene via dehalogenation on graphene and hexagonal boron nitride is investigated by scanning tunneling microscopy experiments and density functional theory calculations. This work reveals how the interactions between molecules and graphene or h-BN grown on Ni(111) govern the surface-confined synthesis of polymers through C–C coupling.

  • 37.
    Morchutt, Claudius
    et al.
    Max Planck Institute Solid State Research, Germany; Ecole Polytech Federal Lausanne, Switzerland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Strasser, Carola
    Max Planck Institute Solid State Research, Germany.
    Starke, Ulrich
    Max Planck Institute Solid State Research, Germany.
    Gutzler, Rico
    Max Planck Institute Solid State Research, Germany.
    Kern, Klaus
    Max Planck Institute Solid State Research, Germany; Ecole Polytech Federal Lausanne, Switzerland.
    Interplay of Chemical and Electronic Structure on the Single-Molecule Level in 2D Polymerization2016In: ACS NANO, ISSN 1936-0851, Vol. 10, no 12, p. 11511-11518Article in journal (Refereed)
    Abstract [en]

    Single layers of covalently linked organic materials in the form of two-dimensional (2D) polymers constitute structures complementary to inorganic 2D materials. The electronic properties of 2D polymers may be manipulated through a deliberate choice of the organic precursors. Here we address the changes in electronic CO structure-from precursor molecule to oligomer by scanning tunneling spectroscopy and ultraviolet photoelectron spectroscopy. For this purpose, we introduce the polymerization reaction of 1,3,5-tris(4-carboxyphenyl)benzene via decarboxylation on Cu(111), which is thoroughly characterized by scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. We present a comprehensive study of a contamination-free on-surface coupling scheme and study how dehydrogenation, decarboxylation, and polymerization affect the electronic structure on the molecular level.

  • 38.
    Nowakowska, Sylwia
    et al.
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland.
    Wäckerlin, Aneliia
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland.
    Kawai, Shigeki
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland; Japan Sci & Technol Agcy JST, PRESTO, Kawaguchi, Saitama 3320012, Japan.
    Ivas, Toni
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland.
    Nowakowski, Jan
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland.
    Fatayer, Shadi
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland; Univ Estadual Campinas, Inst Fis Gleb Wataghin, Dept Fis Aplicada, BR-13083859 Campinas, Brazil.
    Wäckerlin, Christian
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland.
    Nijs, Thomas
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland.
    Meyer, Ernst
    Univ Basel, Dept Phys, CH-4056 Basel, Switzerland.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Stöhr, Meike
    Univ Groningen, Zernike Inst Adv Mat, NL-9747 AG Groningen, Netherlands.
    Gade, Lutz H.
    Heidelberg Univ, Inst Anorgan Chem, D-69120 Heidelberg, Germany.
    Jung, Thomas A.
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland.
    Interplay of weak interactions in the atom-by-atom condensation of xenon within quantum boxes2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 21, no 6, p. 6071-Article in journal (Refereed)
    Abstract [en]

    Condensation processes are of key importance in nature and play a fundamental role in chemistry and physics. Owing to size effects at the nanoscale, it is conceptually desired to experimentally probe the dependence of condensate structure on the number of constituents one by one. Here we present an approach to study a condensation process atom-by-atom with the scanning tunnelling microscope, which provides a direct real-space access with atomic precision to the aggregates formed in atomically defined 'quantum boxes'. Our analysis reveals the subtle interplay of competing directional and nondirectional interactions in the emergence of structure and provides unprecedented input for the structural comparison with quantum mechanical models. This approach focuses on-but is not limited to-the model case of xenon condensation and goes significantly beyond the well-established statistical size analysis of clusters in atomic or molecular beams by mass spectrometry.

  • 39.
    Nowakowska, Sylwia
    et al.
    Department of Physics, University of Basel, Basel, Switzerland.
    Wäckerlin, Aneliia
    Department of Physics, University of Basel, Basel, Switzerland.
    Piquero-Zulaica, Ignacio
    Centro de Física de Materiales (CSIC/UPV-EHU)—Materials Physics Center, San Sebastián, Spain.
    Nowakowski, Jan
    Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, Villigen, PSI, Switzerland.
    Kawai, Shigeki
    Department of Physics, University of Basel, Basel, Switzerland; PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama, Japan.
    Wäckerlin, Christian
    Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, Villigen, PSI, Switzerland.
    Matena, Manfred
    Department of Physics, University of Basel, Basel, Switzerland; Donostia International Physics Center (DIPC), San Sebastián, Spain.
    Nijs, Thomas
    Department of Physics, University of Basel, Basel, Switzerland.
    Fatayer, Shadi
    Department of Physics, University of Basel, Basel, Switzerland; Departamento de Física Aplicada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, Brazil.
    Popova, Olha
    Department of Physics, University of Basel, Basel, Switzerland.
    Ahsan, Aisha
    Department of Physics, University of Basel, Basel, Switzerland.
    Mousavi, S. Fatemeh
    Department of Physics, University of Basel, Basel, Switzerland.
    Ivas, Toni
    Department of Physics, University of Basel, Basel, Switzerland.
    Meyer, Ernst
    Department of Physics, University of Basel, Basel, Switzerland.
    Stöhr, Meike
    Zernike Institute for Advanced Materials, University of Groningen, AG, Groningen, The Netherlands.
    Ortega, J. Enrique
    Centro de Física de Materiales (CSIC/UPV-EHU)—Materials Physics Center, San Sebastián, Spain; Donostia International Physics Center (DIPC), San Sebastián, Spain; Departamento Física Aplicada I, Universidad del País Vasco, San Sebastián, Spain.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Gade, Lutz H.
    Anorganisch-Chemisches Institut, Universität Heidelberg, Heidelberg, Germany.
    Lobo-Checa, Jorge
    Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Zaragoza, Spain; Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain.
    Jung, Thomas A.
    Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, Villigen, PSI, Switzerland.
    Configuring Electronic States in an Atomically Precise Array of Quantum Boxes2016In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 12, no 28, p. 3757-3763Article in journal (Refereed)
    Abstract [en]

    A 2D array of electronically coupled quantum boxes is fabricated by means of on-surface self-assembly assuring ultimate precision of each box. The quantum states embedded in the boxes are configured by adsorbates, whose occupancy is controlled with atomic precision. The electronic interbox coupling can be maintained or significantly reduced by proper arrangement of empty and filled boxes.

  • 40.
    Palma, Carlos-Andres
    et al.
    University of Strasbourg, France.
    Björk, Jonas
    University of Liverpool, UK.
    Bonini, Massimo
    BASF SE..
    Dyer, Matthew S.
    University of Liverpool, UK.
    Llanas-Pallas, Anna
    University of Trieste, Italy.
    Bonifazi, Davide
    University of Trieste, Italy.
    Persson, Mats
    University of Liverpool, UK.
    Samorì, Paolo
    University of Strasbourg, France.
    Tailoring Bicomponent Supramolecular Nanoporous Networks: Phase Segregation, Polymorphism, and Glasses at the Solid−Liquid Interface2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 36, p. 13062-13071Article in journal (Refereed)
    Abstract [en]

    We study the formation of four supramolecular bicomponent networks based on four linear modules (linkers) bridging melamine via triple hydrogen-bonds. We explore at the nanoscale level the phenomena of polymorphism and phase segregation which rule the generation of highly crystalline nanoporous patterns self-assembled at the solid-liquid interface. The investigated linkers include two systems exposing diuracil groups in the R and ω position, naphthalene tetracarboxylic diimide and pyromellitic diimide. In situ scanning tunneling microscopy (STM) investigations revealed that, when blended with melamine, out of the four systems, three are able to form two-dimensional (2D) porous architectures, two of which exhibit highly ordered hexagonal structures, while pyromellitic diimide assembles only into one- dimensional (1D) supramolecular arrays. These bicomponent self-assembled monolayers are used as a test bed to gain detailed insight into phase segregation and polymorphism in 2D supramolecular systems by exploring the contribution of hydrogen-bond energy and periodicity, molecular flexibility, concentration and ratio of the components in solution as well as the effect of annealing via time-dependent and temperature-modulated experiments. These comparative studies, obtained through a joint experimental and computational analysis, offer new insights into strategies toward the bottom-up fabrication of highly ordered tunable nanopatterning at interfaces mediated by hydrogen bonds.

  • 41.
    Palma, Carlos-Andres
    et al.
    Technishe Universität München, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Klappenberger, Florian
    Technische Universität München, Germany.
    Arras, Emmanuel
    Technische Universität München, Germany.
    Kühne, Dirk
    Technische Universität München, Germany.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Barth, Johannes V.
    Technische Universität München, Germany.
    Visualization and thermodynamic encoding of single-molecule partition function projections2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, no 6210Article in journal (Refereed)
    Abstract [en]

    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 temperature-controlled 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.

  • 42.
    Palma, Carlos-Andres
    et al.
    Technishe Universität München, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Rao, Francesco
    Albert-Ludwigs-Universität, Freiburg, Germany.
    Kühne, Dirk
    Technishe Universität München, Germany.
    Klappenberger, Florian
    Technishe Universität München, Germany.
    Barth, Johannes V.
    Technishe Universität München, Germany.
    Topological Dynamics in Supramolecular Rotors2014In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 14, no 8, p. 4461-4468Article in journal (Refereed)
    Abstract [en]

    Artificial molecular switches, rotors, and machines are set to establish design rules and applications beyond their biological counterparts. Herein we exemplify the role of noncovalent interactions and transient rearrangements in the complex behavior of supramolecular rotors caged in a 2D metal–organic coordination network. Combined scanning tunneling microscopy experiments and molecular dynamics modeling of a supramolecular rotor with respective rotation rates matching with 0.2 kcal mol–1 (9 meV) precision, identify key steps in collective rotation events and reconfigurations. We notably reveal that stereoisomerization of the chiral trimeric units entails topological isomerization whereas rotation occurs in a topology conserving, two-step asynchronous process. In supramolecular constructs, distinct displacements of subunits occur inducing a markedly lower rotation barrier as compared to synchronous mechanisms of rigid rotors. Moreover, the chemical environment can be instructed to control the system dynamics. Our observations allow for a definition of mechanical cooperativity based on a significant reduction of free energy barriers in supramolecules compared to rigid molecules.

  • 43.
    Palma, Carlos-Andres
    et al.
    Technishe Universität München, Garching, Germany.
    Diller, Katharina
    Technishe Universität München, Garching, Germany.
    Berger, Reinhard
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Welle, Alexander
    Karlsruher Institut für Technologie, Eggenstein-Leopoldshafen, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Cabellos, Jose Luis Cabellos
    Universidad del País Vasco UPV/EHU, San Sebastián, Spain.
    Mowbray, Duncan John
    Universidad del País Vasco UPV/EHU, San Sebastián, Spain.
    Papageorgiou, Anthoula C.
    Technishe Universität München, Garching, Germany.
    Ivleva, Natalia P.
    Technische Universität München, München, Germany.
    Matich, Sonja
    Walter Schottky Institut, Garching, Germany.
    Margapoti, Emanuela
    Walter Schottky Institut, Garching, Germany.
    Niesser, Reinhard
    Technische Universität München, Germany.
    Menges, Bernhard
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Reichert, Joachim
    Technishe Universität München, Garching, Germany.
    Feng, Xinliang
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Räder, Hans Joachim
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Klappenberger, Florian
    Technishe Universität München, Garching, Germany.
    Rubio, Angel
    Universidad del País Vasco UPV/EHU, San Sebastián, Spain.
    Müllen, Klaus
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Barth, Johannes V.
    Technishe Universität München, Garching, Germany.
    Photo-induced C-C reactions on insulators towards photolithography of graphene nanoarchitectures2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, p. 4651-4658Article in journal (Refereed)
    Abstract [en]

    On-surface chemistry for atomically precise sp2 macromolecules requires top-down lithographic methods on insulating surfaces in order to pattern the long-range complex architectures needed by the semiconductor industry. Here, we fabricate sp2-carbon nm-thin films on insulators and under ultra-high vacuum (UHV) conditions from photo-coupled brominated precursors. We reveal that covalent coupling is initiated by C-Br bond cleavage through photon energies exceeding 4.4 eV, as monitored by laser desorption ionization (LDI) mass spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) gives insight into the mechanisms of C-Br scission and C-C coupling processes. Further, unreacted material can be sublimed and the coupled sp2-carbon precursors can be graphitized by e-beam treatment at 500°C, demonstrating promising applications in photolithography of graphene nanoarchitectures. Our results present UV-induced reactions on insulators for the formation of all sp2-carbon architectures, thereby converging top-down lithography and bottom-up on-surface chemistry into technology.

  • 44.
    Rastgoo Lahrood, Atena
    et al.
    Technical University of Munich, Germany; Nanosyst Initiat Munich, Germany; Centre NanoScience, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Heckl, Wolfgang M.
    Technical University of Munich, Germany; Nanosyst Initiat Munich, Germany; Centre NanoScience, Germany; Deutsch Museum, Germany.
    Lackinger, Markus
    Technical University of Munich, Germany; Nanosyst Initiat Munich, Germany; Centre NanoScience, Germany; Deutsch Museum, Germany.
    1,3-Diiodobenzene on Cu(111) - an exceptional case of on-surface Ullmann coupling2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 68, p. 13301-13304Article in journal (Refereed)
    Abstract [en]

    Ullmann coupling of 1,3-diiodobenzene is studied on Cu(111) surfaces in ultra-high vacuum (UHV). In situ Scanning Tunneling Microscopy (STM) at room temperature revealed an unexpected ordered arrangement of highly uniform reaction products adsorbed atop a closed iodine monolayer.

  • 45.
    Rastgoo-Lahrood, Atena
    et al.
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Lischka, Matthias
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Eichhorn, Johanna
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Kloft, Stephan
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Fritton, Massimo
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Strunskus, Thomas
    University of Kiel, Germany.
    Samanta, Debabrata
    University of Siegen, Germany.
    Schmittel, Michael
    University of Siegen, Germany.
    Heckl, Wolfgang M.
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Lackinger, Markus
    Technical University of Munich, Germany; Deutsch Museum, Germany; Nanosyst Initiat Munich, Germany; Centre Nanosci, Germany.
    Post-Synthetic Decoupling of On-Surface-Synthesized Covalent Nanostructures from Ag(111)2016In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 27, p. 7650-7654Article in journal (Refereed)
    Abstract [en]

    The on-surface synthesis of covalent organic nanosheets driven by reactive metal surfaces leads to strongly adsorbed organic nanostructures, which conceals their intrinsic properties. Hence, reducing the electronic coupling between the organic networks and commonly used metal surfaces is an important step towards characterization of the true material. We demonstrate that post-synthetic exposure to iodine vapor leads to the intercalation of an iodine monolayer between covalent polyphenylene networks and Ag(111) surfaces. The experimentally observed changes from surface-bound to detached nanosheets are reproduced by DFT simulations. These findings suggest that the intercalation of iodine provides a material that shows geometric and electronic properties substantially closer to those of the freestanding network.

  • 46.
    Robin, Abel
    et al.
    University of Liverpool, UK.
    Marnell, Lisa
    University of Liverpool, UK.
    Björk, Jonas
    University of Liverpool, UK.
    Dyer, Matthew S.
    University of Liverpool, UK.
    Bermudez, Phaedra Silva
    University of Liverpool, UK.
    Haq, Sam
    University of Liverpool, UK.
    Barrett, Steve
    University of Liverpool, UK.
    Persson, Mats
    University of Liverpool, UK.
    Minoia, Andrea
    University of Mons-Hainaut/Materia Nova, Mons, Belgium.
    Lazzorini, Roberto
    University of Mons-Hainaut/Materia Nova, Mons, Belgium.
    Raval, Rasmita
    University of Liverpool, UK.
    Adsorption and Organization of the Organic Radical 3-Carboxyproxyl on a Cu(110) Surface: A Combined STM, RAIRS, and DFT Study2009In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 113, no 30, p. 13223-13230Article in journal (Refereed)
    Abstract [en]

    We report on a combined experimental and theoretical study of the adsorption of the paramagnetic organic radical 2,2,5,5-tetramethyl-3-carboxypyrrolidine nitroxide (3-carboxyproxyl, 3CP) on a Cu(110) surface. Information from scanning tunneling microscopy (STM), reflection absorption infrared spectroscopy, and periodic density functional theory (DFT) calculations reveals important insights into the nature of the molecule-metal interface. We find that the molecule is robustly anchored to the surface via the formation of two Cu-O bonds between the carboxylate functionality and specific short-bridge adsorption sites on the Cu(110) surface. The adsorbed organic radicals appear in STM as discrete entities on the surface and can be imaged with submolecular resolution. We observe a tendency for local 2D ordering. Importantly, 3CP molecules adopt a preferred site, dictated by the strong interaction of the carboxylate groups and the steric repulsion of the methyl groups with the surface which orient the molecular ring almost perpendicular with respect to the surface. This conformation forces the NO radical away from the surface, and DFT calculations provide strong indications for the survival of the unpaired spin localized on the NO radical.

  • 47.
    Salinas, Borja Cirera
    et al.
    Technische Universität München, Garching, Germany.
    Zhang, Yi-Qi
    Technische Universität München, Garching, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Klyatskaya, Svetlana
    Karlsruhe Institute of Technology, Garching, Germany.
    Chen, Zhi
    Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.
    Ruben, Mario
    Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.
    Barth, Johannes V.
    Technische Universität München, Garching, Germany.
    Klappenberger, Florian
    Technische Universität München, Garching, Germany.
    Synthesis of Extended Graphdiyne Wires by Vicinal Surface Templating2014In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 14, no 4, p. 1891-1897Article in journal (Refereed)
    Abstract [en]

    Surface-assisted covalent synthesis currently evolves into an important approach for the fabrication of functional nanostructures at interfaces. Here, we employ scanning tunneling microscopy to investigate the homo-coupling reaction of linear, terminal alkyne-functionalized polyphenylene building-blocks on noble metal surfaces under ultra-high vacuum. On the flat Ag(111) surface thermal activation triggers a variety of side-reactions resulting in irregularly-branched polymeric networks. Upon alignment along the step-edges of the Ag(877) vicinal surface drastically improves the chemoselectivity of the linking process permitting the controlled synthesis of extended-graphdiyne wires with lengths reaching 30 nm. The ideal hydrocarbon scaffold is characterized by density functional theory as a 1D, direct band gap semiconductor material with both HOMO and LUMO-derived bands promisingly isolated within the electronic structure. The templating approach should be applicable to related organic precursors and different reaction schemes thus bears general promise for the engineering of novel low-dimensional carbon-based materials.

  • 48.
    Sanchez-Grande, Ana
    et al.
    IMDEA Nanociencia, Spain.
    de la Torre, Bruno
    Palacky Univ Olomouc, Czech Republic; Czech Acad Sci, Czech Republic.
    Santos, Jose
    IMDEA Nanociencia, Spain.
    Cirera, Borja
    IMDEA Nanociencia, Spain.
    Lauwaet, Koen
    IMDEA Nanociencia, Spain.
    Chutora, Taras
    Palacky Univ Olomouc, Czech Republic.
    Edalatmanesh, Shayan
    Czech Acad Sci, Czech Republic.
    Mutombo, Pingo
    Czech Acad Sci, Czech Republic.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zboril, Radek
    Palacky Univ Olomouc, Czech Republic.
    Miranda, Rodolfo
    IMDEA Nanociencia, Spain; Univ Autonoma Madrid, Spain.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jelinek, Pavel
    Palacky Univ Olomouc, Czech Republic; Czech Acad Sci, Czech Republic.
    Martin, Nazario
    IMDEA Nanociencia, Spain; Univ Complutense, Spain.
    Ecija, David
    IMDEA Nanociencia, Spain.
    On-Surface Synthesis of Ethynylene-Bridged Anthracene Polymers2019In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 58, no 20, p. 6559-6563Article in journal (Refereed)
    Abstract [en]

    Engineering low-band-gap -conjugated polymers is a growing area in basic and applied research. The main synthetic challenge lies in the solubility of the starting materials, which precludes advancements in the field. Here, we report an on-surface synthesis protocol to overcome such difficulties and produce poly(p-anthracene ethynylene) molecular wires on Au(111). To this aim, a quinoid anthracene precursor with =CBr2 moieties is deposited and annealed to 400K, resulting in anthracene-based polymers. High-resolution nc-AFM measurements confirm the nature of the ethynylene-bridge bond between the anthracene moieties. Theoretical simulations illustrate the mechanism of the chemical reaction, highlighting three major steps: dehalogenation, diffusion of surface-stabilized carbenes, and homocoupling, which enables the formation of an ethynylene bridge. Our results introduce a novel chemical protocol to design -conjugated polymers based on oligoacene precursors and pave new avenues for advancing the emerging field of on-surface synthesis.

  • 49.
    Shchyrba, Aneliia
    et al.
    University of Basel, Switzerland .
    Waeckerlin, Christian
    Paul Scherrer Institute, Villigen, Switzerland .
    Nowakowski, Jan
    Paul Scherrer Institute, Villigen, Switzerland .
    Nowakowska, Sylwia
    University of Basel, Switzerland .
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Fatayer, Shadi
    University of Basel, Switzerland .
    Girovsky, Jan
    Paul Scherrer Institute, Villigen, Switzerland .
    Nijs, Thomas
    University of Basel, Switzerland .
    Martens, Susanne C.
    University of Basel, Switzerland; Heidelberg University, Germany .
    Kleibert, Armin
    Paul Scherrer Institute, Villigen, Switzerland .
    Stoehr, Meike
    University of Groningen, Netherlands .
    Ballav, Nirmalya
    Indian Institute of Science Education and Research, Pune, India.
    Jung, Thomas A.
    Paul Scherrer Institute, Villigen, Switzerland .
    Gade, Lutz H.
    Heidelberg University, Germany .
    Controlling the dimensionality of on-surface coordination polymers via endo- or exoligation2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 26, p. 9355-9363Article in journal (Refereed)
    Abstract [en]

    The formation of on-surface coordination polymers is controlled by the interplay of chemical reactivity and structure of the building blocks, as well as by the orientating role of the substrate registry. Beyond the predetermined patterns of structural assembly, the chemical reactivity of the reactants involved may provide alternative pathways in their aggregation. Organic molecules, which are transformed in a surface reaction, may be subsequently trapped via coordination of homo- or heterometal adatoms, which may also play a role in the molecular transformation. The amino-functionalized perylene derivative, 4,9-diaminoperylene quinone-3,10-diimine (DPDI), undergoes specific levels of dehydrogenation (-1 H-2 or -3 H-2) depending on the nature of the present adatoms (Fe, Co, Ni or Cu). In this way, the molecule is converted to an endo- or an exoligand, possessing a concave or convex arrangement of ligating atoms, which is decisive for the formation of either ID or 2D coordination polymers.

  • 50.
    Szekrényes, Zsolt
    et al.
    Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Hungary, Budapest.
    Kamarás, Katalin
    Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Hungary, Budapest.
    Tarczay, György
    Laboratory of Molecular Spectroscopy, Institute of Chemistry, Eötvös Loránd University, H-1518 Budapest, Hungary.
    Llanes-Pallás, Anna
    Dipartimento di Scienze Farmaceutiche and INSTM UdR di Trieste, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy.
    Marangoni, Tomas
    Dipartimento di Scienze Farmaceutiche and INSTM UdR di Trieste, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy.
    Prato, Maurizio
    Dipartimento di Scienze Farmaceutiche and INSTM UdR di Trieste, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy.
    Bonifazi, Davide
    Department of Chemistry, University of Namur (FUNDP), Rue de Bruxelles 61, 5000 Namur, Belgium.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Hanke, Felix
    Surface Science Research Centre, University of Liverpool, UK.
    Persson, Mats
    Surface Science Research Centre, University of Liverpool, UK.
    Melting of Hydrogen Bonds in Uracil Derivatives Probed by Infrared Spectroscopy and ab Initio Molecular Dynamics2012In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 116, no 15, p. 4626-4633Article in journal (Refereed)
    Abstract [en]

    The thermal response of hydrogen bonds is a crucial aspect in the self-assembly of molecular nanostructures. To gain a detailed understanding of their response, we investigated infrared spectra of monomers and hydrogen-bonded dimers of two uracil-derivative molecules, supported by density functional theory calculations. Matrix isolation spectra of monomers, temperature dependence in the solid state, and ab initio molecular dynamics calculations give a comprehensive picture about the dimer structure and dynamics of such systems as well as a proper assignment of hydrogen-bond affected bands. The evolution of the hydrogen bond melting is followed by calculating the C═O···H–N distance distributions at different temperatures. The result of this calculation yields excellent agreement with the H-bond melting temperature observed by experiment.

12 1 - 50 of 55
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf