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Björk, J. (2016). Formation mechanisms of covalent nanostructures from density functional theory. In: André Gourdon (Ed.), Proceedings of International Workshop on On-Surface Synthesis: . Paper presented at International Workshop on On-Surface Synthesis, 25-30 May, 2014 (pp. 269-287). Cham: Springer
Open this publication in new window or tab >>Formation mechanisms of covalent nanostructures from density functional theory
2016 (English)In: Proceedings of International Workshop on On-Surface Synthesis, Cham: Springer, 2016, p. 269-287Conference paper, Published 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.

Place, publisher, year, edition, pages
Cham: Springer, 2016
Series
Advances in Atom and Single Molecule Machines, ISSN 2193-9691 ; 8
National Category
Nano Technology Physical Chemistry Theoretical Chemistry
Identifiers
urn:nbn:se:liu:diva-124196 (URN)10.1007/978-3-319-26600-8_13 (DOI)000373067900013 ()9783319265988 (ISBN)9783319266008 (ISBN)
Conference
International Workshop on On-Surface Synthesis, 25-30 May, 2014
Available from: 2016-01-21 Created: 2016-01-21 Last updated: 2017-10-18Bibliographically approved
Zhang, Y.-Q., Björk, J., Barth, J. V. & Klappenberger, F. (2016). Intermolecular Hybridization Creating Nanopore Orbital in a Supramolecular Hydrocarbon Sheet. Nano letters (Print), 16(7), 4274-4281
Open this publication in new window or tab >>Intermolecular Hybridization Creating Nanopore Orbital in a Supramolecular Hydrocarbon Sheet
2016 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 16, no 7, p. 4274-4281Article in journal (Refereed) Published
Abstract [en]

Molecular orbital engineering is a key ingredient for the design of organic devices. Intermolecular hybridization promises efficient charge carrier transport but usually requires dense packing for significant wave function overlap. Here we use scanning tunneling spectroscopy to spatially resolve the electronic structure of a surface-confined nanoporous supramolecular sheet of a prototypical hydrocarbon compound featuring terminal alkyne (CCH) groups. Surprisingly, localized nanopore orbitals are observed, with their electron density centered in the cavities surrounded by the functional moieties. Density functional theory calculations reveal that these new electronic states originate from the intermolecular hybridization of six in-plane x-orbitals of the carbon carbon triple bonds, exhibiting significant electronic splitting and an energy downshift of approximately 1 eV. Importantly, these nanopore states are distinct from previously reported interfacial states. We unravel the underlying connection between the formation of nanopore orbital and geometric arrangements of functional groups, thus demonstrating the generality of applying related orbital engineering concepts in various types of porous organic structures.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2016
Keywords
Electronic structure; intermolecular hybridization; orbital engineering; porous materials; scanning tunneling spectroscopy
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-130410 (URN)10.1021/acs.nanolett.6b01324 (DOI)000379794200044 ()27253516 (PubMedID)
Note

Funding Agencies|DFG Excellence Cluster Munich Center for Advanced Photonics; ERC Advanced Grant MolArt [247229]

Available from: 2016-08-15 Created: 2016-08-05 Last updated: 2017-11-28
Björk, J. (2016). Reaction mechanisms for on-surface synthesis of covalent nanostructures. Journal of Physics: Condensed Matter, 28(8), 083002
Open this publication in new window or tab >>Reaction mechanisms for on-surface synthesis of covalent nanostructures
2016 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 28, no 8, p. 083002-Article, review/survey (Refereed) Published
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.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2016
National Category
Physical Chemistry Theoretical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-124555 (URN)10.1088/0953-8984/28/8/083002 (DOI)000369479200002 ()26836411 (PubMedID)
Available from: 2016-02-02 Created: 2016-02-02 Last updated: 2018-02-21
Cirera, B., Giménez-Agulló, N., Björk, J., Martínez-Peña, F., Martin-Jimenez, A., Rodriguez-Fernandez, J., . . . Ecija, D. (2016). Thermal selectivity of intermolecular versus intramolecular reactions on surfaces. Nature Communications, 7(11002)
Open this publication in new window or tab >>Thermal selectivity of intermolecular versus intramolecular reactions on surfaces
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2016 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, no 11002Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Nature Publishing Group, 2016
National Category
Physical Chemistry Theoretical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-126116 (URN)10.1038/ncomms11002 (DOI)000372020400001 ()26964764 (PubMedID)
Note

Funding agencies: EU (ERC) [279313]; EU (EC) [631396]; EU (FEDER) [CTQ2014-56295-R]; Spanish Ministerio de Economia y Competitividad (MINECO) [CTQ2014-56295-R, RYC-2012-11133, RYC-2012-11231, CTQ2014-52974-REDC, SEV-2013-0319]; Comunidad de Madrid (project MAD2D); Generali

Available from: 2016-03-15 Created: 2016-03-15 Last updated: 2017-11-30
Kawai, S., Foster, A. S., Björkman, T., Nowakowska, S., Björk, J., Canova, F. F., . . . Meyer, E. (2016). Van der Waals interactions and the limits of isolated atom models at interfaces. Nature Communications, 7, Article ID 11559.
Open this publication in new window or tab >>Van der Waals interactions and the limits of isolated atom models at interfaces
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2016 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, article id 11559Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Nature Publishing Group, 2016
National Category
Condensed Matter Physics Physical Chemistry
Identifiers
urn:nbn:se:liu:diva-128003 (URN)10.1038/ncomms11559 (DOI)000375938600001 ()27174162 (PubMedID)
Note

Funding agencies:  Japan Science and Technology Agency (JST); Swiss National Science Foundation; Swiss Nanoscience Institute; COST Action [MP1303]; Academy of Finland through its Centres of Excellence Program [915804]; EU project PAMS [610446]

Available from: 2016-05-16 Created: 2016-05-16 Last updated: 2017-11-30
Rastgoo Lahrood, A., Björk, J., Heckl, W. M. & Lackinger, M. (2015). 1,3-Diiodobenzene on Cu(111) - an exceptional case of on-surface Ullmann coupling. Chemical Communications, 51(68), 13301-13304
Open this publication in new window or tab >>1,3-Diiodobenzene on Cu(111) - an exceptional case of on-surface Ullmann coupling
2015 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 68, p. 13301-13304Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2015
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-121151 (URN)10.1039/c5cc04453g (DOI)000359455100013 ()26207945 (PubMedID)
Note

Funding Agencies|DFG [LA1842/4-1]; Nanosystems Initiative Munich

Available from: 2015-09-08 Created: 2015-09-08 Last updated: 2017-12-04
Gottardi, S., Muller, K., Bignardi, L., Carlos Moreno-Lopez, J., Tuan Anh Pham; Ivashenko, O., Yablonskikh, M., . . . Stohr, M. (2015). Comparing Graphene Growth on Cu(111) versus Oxidized Cu(111). Nano letters (Print), 15(2), 917-922
Open this publication in new window or tab >>Comparing Graphene Growth on Cu(111) versus Oxidized Cu(111)
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2015 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, no 2, p. 917-922Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
American Chemical Society, 2015
Keywords
Graphene; copper oxide; dielectric; catalysis; electronic properties; ARPES; STM
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-115824 (URN)10.1021/nl5036463 (DOI)000349578000018 ()25611528 (PubMedID)
Note

Funding Agencies|Foundation for Fundamental Research on Matter (FOM) part of The Netherlands Organization for Scientific Research (NWO); European Research Council [ERC-2012-StG 307760-SURFPRO]; NWO (Chemical Sciences, VIDI) [700.10.424]; NWO (Chemical Sciences, VENI) [722.012.010]

Available from: 2015-03-20 Created: 2015-03-20 Last updated: 2017-12-04
Morchutt, C., Björk, J., Krotzky, S., Gutzler, R. & Kern, K. (2015). Covalent coupling via dehalogenation on Ni(111) supported boron nitride and graphene. Chemical Communications, 51(12), 2440-2443
Open this publication in new window or tab >>Covalent coupling via dehalogenation on Ni(111) supported boron nitride and graphene
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2015 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 12, p. 2440-2443Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2015
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-114464 (URN)10.1039/C4CC07107g (DOI)000348921600060 ()25568901 (PubMedID)
Available from: 2015-02-20 Created: 2015-02-20 Last updated: 2017-12-04
Nowakowska, S., Wäckerlin, A., Kawai, S., Ivas, T., Nowakowski, J., Fatayer, S., . . . Jung, T. A. (2015). Interplay of weak interactions in the atom-by-atom condensation of xenon within quantum boxes. Nature Communications, 21(6), 6071
Open this publication in new window or tab >>Interplay of weak interactions in the atom-by-atom condensation of xenon within quantum boxes
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2015 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 21, no 6, p. 6071-Article in journal (Refereed) Published
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.

National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:liu:diva-114463 (URN)10.1038/ncomms7071 (DOI)000348830500001 ()25608225 (PubMedID)
Note

We would like to acknowledge the financial support from the National Centre of Competence in Research `Nanoscience' (NCCR-Nano), Swiss Nanoscience Institute (SNI), Swiss National Science Foundation (grants no. 200020-149713, 206021-121461), the Sao Paulo Research Foundation (grant no. 2013/04855-0), Netherlands Organisation for Scientific Research NWO (Chemical Sciences, VIDI-grant no. 700.10.424), the European Research Council (ERC-2012-StG 307760-SURFPRO), University of Basel, University of Heidelberg, Linkoping University, University of Groningen, Paul Scherrer Institute and the Japan Science and Technology Agency (JST) `Precursory Research for Embryonic Science and Technology (PRESTO)' for a project of `Molecular technology and creation of new function'. We sincerely thank Marco Martina, Remy Pawlak and Alexander Bubendorf for the support during measurements, as well as Gerhard Meyer, Silvia Schintke, Jorge Lobo-Checa, Manfred Matena and Milos. Baljozovic ' for helpful discussions.

Available from: 2015-02-20 Created: 2015-02-20 Last updated: 2017-12-04
Klappenberger, F., Zhang, Y.-Q., Björk, J., Klyatskaya, S., Ruben, M. & Barth, J. V. (2015). On-Surface Synthesis of Carbon-Based Scaffolds and Nanomaterials Using Terminal Alkynes. Accounts of Chemical Research, 48(7), 2140-2150
Open this publication in new window or tab >>On-Surface Synthesis of Carbon-Based Scaffolds and Nanomaterials Using Terminal Alkynes
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2015 (English)In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 48, no 7, p. 2140-2150Article, review/survey (Refereed) Published
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.

Place, publisher, year, edition, pages
American Chemical Society, 2015
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-120744 (URN)10.1021/acs.accounts.5b00174 (DOI)000358556400038 ()26156663 (PubMedID)
Note

Funding Agencies|European Union via ERC Advanced Grant MolArt [247299]; German Research Foundation (DFG) via SPP program 1459

Available from: 2015-08-24 Created: 2015-08-24 Last updated: 2017-12-04
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1345-0006

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