Bromine adatom promoted C–H bond activation in terminal alkynes at room temperature on Ag(111)

Liu, Jing; Chen, Qiwei; He, Qilin; Zhang, Yajie; Fu, Xiangyu; Wang, Yongfeng; Zhao, Dahui; Chen, Wei; Xu, Guo Qin; Wu, Kai

doi:10.1039/c7cp07972a

Cited by 40 publications

(63 citation statements)

References 46 publications

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“…The surface‐assisted bottom‐up fabrication of nanomaterials utilizing rationally designed molecular precursors as building blocks which are assembled on metal surfaces represents an attractive alternative to traditional wet‐chemistry because it offers access to high quality products achieved through new reaction pathways . Precursors carrying alkyne functional groups express an intriguingly rich surface chemistry including dehydrogenation, homo‐coupling, cross‐coupling, cyclotrimerization, and metathesis reactions as well as the formation of enyne, metal‐organic, and organometallic linkages . They constitute promising building‐blocks for the surface‐guided construction of low‐dimensional architectures partly expressing covalent character .…”

Section: Introductionmentioning

confidence: 85%

On‐Surface Activation of Trimethylsilyl‐Terminated Alkynes on Coinage Metal Surfaces

Zhang

Chen

et al. 2019

ChemPhysChem

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The controlled attachment of protecting groups combined with the ability to selectively abstract them is central to organic synthesis. The trimethylsilyl (TMS) functional group is a popular protecting group in solution. However, insights on its activation behavior under ultra-high vacuum (UHV) and surface-confined conditions are scarce. Here we investigate a series of TMSprotected alkyne precursors via scanning tunneling microscopy (STM) regarding their compatibility with organic molecular beam epitaxy (OMBE) and their potential deprotection on various coinage metal surfaces. After in-situ evaporation on the substrates held in UHV at room temperature, we find that all molecules arrived and adsorbed as intact units forming ordered supramolecular aggregates stabilized by non-covalent interac-tions. Thus, TMS-functionalized alkyne precursors with weights up to 1100 atomic mass units are stable against OMBE evaporation in UHV. Furthermore, the TMS activation through thermal annealing is investigated with STM and X-ray photoelectron spectroscopy (XPS). We observe that deprotection starts to occur between 400 K and 500 K on the copper and gold surfaces, respectively. In contrast, on silver surfaces, the TMS-alkyne bond remains stable up to temperatures where molecular desorption sets in ( � 600 K). Hence, TMS functional groups can be utilized as leaving groups on copper and gold surfaces while they serve as protecting groups on silver surfaces.

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Section: Introductionmentioning

confidence: 85%

On‐Surface Activation of Trimethylsilyl‐Terminated Alkynes on Coinage Metal Surfaces

Zhang

Chen

et al. 2019

ChemPhysChem

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“…It should be noticed that they observed the organometallic chains at RT and their conversion to covalent molecular chains. This anomaly may be attributed to the existence of detached Br adatoms . Other competitive reactions such as cyclotrimerization were also studied.…”

Section: C−x and C−h Activation Of Sp‐carbonmentioning

confidence: 99%

On‐Surface Synthesis of One‐Dimensional Carbon‐Based Nanostructures via C−X and C−H Activation Reactions

Kang

2019

ChemPhysChem

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The past decades have witnessed the emergence of lowdimensional carbon-based nanostructures owing to their unique properties and various subsequent applications. It is of fundamental importance to explore ways to achieve atomically precise fabrication of these interesting structures. The newly developed on-surface synthesis approach provides an efficient strategy for this challenging issue, demonstrating the potential of atomically precise preparation of low-dimensional nanostructures. Up to now, the formation of various surface nanostructures, especially carbon-based ones, such as graphene nanoribbons (GNRs), kinds of organic (organometallic) chains and films, have been achieved via on-surface synthesis strategy, in which in-depth understanding of the reaction mechanism has also been explored. This review article will provide a general overview on the formation of one-dimensional carbon-based nanostructures via on-surface synthesis method. In this review, only a part of the on-surface chemical reactions (specifically, CÀ X (X=Cl, Br, I) and CÀ H activation reactions) under ultra-high vacuum conditions will be covered. CÀ X and CÀ H Activation of sp-CarbonOn-surface dehalogenative/dehydrogenative homocoupling reactions of precursors functionalized with alkynyl groups have manifested great potential for the fabrication of low-dimensional carbon-based nanostructures involving acetylenic scaffolds, such as carbyne, graphyne and graphdiyne. Sun [8] et al. reported the successful formation of one-dimensional wires with acetylenic scaffolding via on-surface CÀ Br activation of sphybridized carbon atoms. They designed and synthesized the precursor 4,4'-di(bromoethynyl)-1,1'-biphenyl (bBEBP), and then deposited it on Au(111) substrate at RT. After annealing tõ 320 K, one-dimensional chains were formed on the surface. These chains were composed of two kinds of alternating protrusions. Thus, an organometallic chain structure combined with CÀ AuÀ C was proposed (as shown in Figure 1a), with the DFT model being in good agreement with the STM image. Further annealing to~425 K leaded to Au atoms released from the organometallic chains, and consequently, CÀ C coupled molecular chains with acetylenic linkages were obtained (as shown in Figure 1b). The disappearance of dot protrusions between biphenyl groups can be observed from the STM images. Additionally, the feasibility to incorporate acetylenic scaffoldings into two-dimensional networks was also be demonstrated in this work. Liu et al. analogously synthesized graphdiyne zigzag chains and macrocycles. Statistical results showed that macrocycles were preferred to form in low coverage of organometallic intermediates. [9] These works act as a supplement to our understandings of on-surface dehalogenative homocoupling reactions, and moreover, make CÀ X activation of sp-hybridized carbon a suitable strategy to synthesize highquality nanostructures with acetylenic linkages.Glaser coupling, discovered by Glaser [10] in 1869, can also be applied to the preparation of chain structures...

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“…Still implying intermediate organometallic structures in multistep reactions, a surprising example has been reported in 2018 where the monomer, i.e., 2,5-diethynyl-1,4- bis (4-bromophenyl-ethynyl)benzene (2Br-DEBPB) could theoretically react according to the Ullmann and Glaser coupling mechanisms (see Figure 22A) [124].…”

Section: Coupling Modes Used For the Design Of 1d Macromolecular Omentioning

confidence: 99%

Recent Advances of Hierarchical and Sequential Growth of Macromolecular Organic Structures on Surface

Pigot

Dumur

2019

Materials

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The fabrication of macromolecular organic structures on surfaces is one major concern in materials science. Nanoribbons, linear polymers, and porous nanostructures have gained a lot of interest due to their possible applications ranging from nanotemplates, catalysis, optoelectronics, sensors, or data storage. During decades, supramolecular chemistry has constituted an unavoidable approach for the design of well-organized structures on surfaces displaying a long-range order. Following these initial works, an important milestone has been established with the formation of covalent bonds between molecules. Resulting from this unprecedented approach, various nanostructures of improved thermal and chemical stability compared to those obtained by supramolecular chemistry and displaying unique and unprecedented properties have been developed. However, a major challenge exists: the growth control is very delicate and a thorough understanding of the complex mechanisms governing the on-surface chemistry is still needed. Recently, a new approach consisting in elaborating macromolecular structures by combining consecutive steps has been identified as a promising strategy to elaborate organic structures on surface. By designing precursors with a preprogrammed sequence of reactivity, a hierarchical or a sequential growth of 1D and 2D structures can be realized. In this review, the different reaction combinations used for the design of 1D and 2D structures are reported. To date, eight different sequences of reactions have been examined since 2008, evidencing the intense research activity existing in this field.

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Bromine adatom promoted C–H bond activation in terminal alkynes at room temperature on Ag(111)

Cited by 40 publications

References 46 publications

On‐Surface Activation of Trimethylsilyl‐Terminated Alkynes on Coinage Metal Surfaces

On‐Surface Activation of Trimethylsilyl‐Terminated Alkynes on Coinage Metal Surfaces

On‐Surface Synthesis of One‐Dimensional Carbon‐Based Nanostructures via C−X and C−H Activation Reactions

Recent Advances of Hierarchical and Sequential Growth of Macromolecular Organic Structures on Surface

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