Unraveling the Mechanism of the Covalent Coupling Between Terminal Alkynes on a Noble Metal

Björk, Jonas; Zhang, Yi‐Qi; Klappenberger, Florian; Barth, Johannes V.; Stafström, Sven

doi:10.1021/jp5002918

Cited by 77 publications

(101 citation statements)

References 57 publications

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“…Glaser-Hay coupling, a wellknown named reaction, proceeds identically through the dehydrogenation of a terminal alkyne with a Cu(I) ion and establishment of a Cu-acetylide intermediate. The mechanism for the surface-assisted covalent coupling of terminal alkynes on Ag (111) was elucidated using density functional theory (DFT)-based transition state calculations, 18 suggesting a hierarchic reaction pathway that is fundamentally different from the classical coupling schemes in wet chemistry. However, research findings on Ag-related syntheses of butadiyne moieties remain scarce.…”

Section: Alkynylationmentioning

confidence: 99%

Silver-catalysed reactions of alkynes: recent advances

2015

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Silver is a less expensive noble metal. Superior alkynophilicity due to π-coordination with the carbon-carbon triple bond makes silver salts ideal catalysts for alkyne-based organic reactions. This review highlights the progress in alkyne chemistry via silver catalysis primarily over the past five years (ca. 2010-2014). The discussion is developed in terms of the bond type formed with the acetylenic carbon (i.e., C-C, C-N, C-O, C-Halo, C-P and C-B). Compared with other coinage metals such as Au and Cu, silver catalysis is frequently observed to be unique. This critical review clearly indicates that silver catalysis provides a significant impetus to the rapid evolution of alkyne-based organic reactions, such as alkynylation, hydrofunctionalization, cycloaddition, cycloisomerization, and cascade reactions.

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Section: Alkynylationmentioning

confidence: 99%

Silver-catalysed reactions of alkynes: recent advances

2015

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“…It has been demonstrated that thermal activation can trigger both reactions on various flat metal surfaces (i.e., Au, Ag, Cu), whereby a preference for cyclotrimerization and homocoupling is expressed on Au(111) and Ag(111), respectively. As a drawback, their complex, multistep pathways render these reactions prone to a variety of side‐reactions, thus achieving selective alkyne coupling remains challenging.…”

Section: Figurementioning

confidence: 99%

“…Thus, the explanation of the observed temperature dependence of the prevailing reactions requires a more complex scenario. For its discussion (Figure e), we simplify the proposed pathway for homocoupling to two major steps: 1) Two pristine molecules couple to an intermediate (INT), which is bound to the substrate and has two hydrogen atoms pointing away from the substrate; 2) The INT finalizes the homocoupling by two subsequent dehydrogenation steps. Previous results indicate that cyclotrimerization also proceeds via a two‐step reaction with essentially the same INT .…”

Section: Figurementioning

confidence: 99%

Terminal Alkyne Coupling on a Corrugated Noble Metal Surface: From Controlled Precursor Alignment to Selective Reactions

Lin

Zhang

Björk

et al. 2017

Chemistry A European J

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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.

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“…In this context, the homocoupling reaction of terminal alkyne tectons has raised great hopes for the construction of graphdiyne‐related nanostructures . However, the intricate coupling mechanism and the occurrence of cross‐linking side reactions prevented so far the production of high‐quality 2D architectures. With the help of substrate templating mechanisms, which proved efficient for increasing regio‐ and chemoselectivity, so‐called extended graphdiyne (GDY) nanowires were realized on a vicinal surface .…”

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confidence: 99%

Functionalized Graphdiyne Nanowires: On‐Surface Synthesis and Assessment of Band Structure, Flexibility, and Information Storage Potential

Klappenberger

Hellwig

et al. 2018

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Carbon nanomaterials exhibit extraordinary mechanical and electronic properties desirable for future technologies. Beyond the popular sp -scaffolds, there is growing interest in their graphdiyne-related counterparts incorporating both sp and sp bonding in a regular scheme. Herein, we introduce carbonitrile-functionalized graphdiyne nanowires, as a novel conjugated, one-dimensional (1D) carbon nanomaterial systematically combining the virtues of covalent coupling and supramolecular concepts that are fabricated by on-surface synthesis. Specifically, a terphenylene backbone is extended with reactive terminal alkyne and polar carbonitrile (CN) moieties providing the required functionalities. It is demonstrated that the CN functionalization enables highly selective alkyne homocoupling forming polymer strands and gives rise to mutual lateral attraction entailing room-temperature stable double-stranded assemblies. By exploiting the templating effect of the vicinal Ag(455) surface, 40 nm long semiconducting nanowires are obtained and the first experimental assessment of their electronic band structure is achieved by angle-resolved photoemission spectroscopy indicating an effective mass below 0.1m for the top of the highest occupied band. Via molecular manipulation it is showcased that the novel oligomer exhibits extreme mechanical flexibility and opens unexplored ways of information encoding in clearly distinguishable CN-phenyl trans-cis species. Thus, conformational data storage with density of 0.36 bit nm and temperature stability beyond 150 K comes in reach.

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Unraveling the Mechanism of the Covalent Coupling Between Terminal Alkynes on a Noble Metal

Cited by 77 publications

References 57 publications

Silver-catalysed reactions of alkynes: recent advances

Silver-catalysed reactions of alkynes: recent advances

Terminal Alkyne Coupling on a Corrugated Noble Metal Surface: From Controlled Precursor Alignment to Selective Reactions

Functionalized Graphdiyne Nanowires: On‐Surface Synthesis and Assessment of Band Structure, Flexibility, and Information Storage Potential

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