On-surface synthesis of π-conjugated ladder-type polymers comprising nonbenzenoid moieties

Urgel, José I.; Bock, Julian; Giovannantonio, Marco Di; Ruffieux, Pascal; Pignedoli, Carlo A.; Kivala, Milan; Fasel, Román

doi:10.1039/d1ra03253d

Cited by 6 publications

(8 citation statements)

References 46 publications

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“…8,21,[30][31][32][33][34][35] Most of them have utilized strategies based on oxidative ring closure, 8,36 bond rotation 37 or the use of molecular precursors with embedded 5-membered rings. 38,39 Therefore, it is highly desirable to provide new strategies that allow the controlled formation and detailed analysis of such non-benzenoid molecules.…”

Section: Introductionmentioning

confidence: 99%

On-surface synthesis of non-benzenoid conjugated polymers by selective atomic rearrangement of ethynylarenes

et al. 2023

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Section: Introductionmentioning

confidence: 99%

On-surface synthesis of non-benzenoid conjugated polymers by selective atomic rearrangement of ethynylarenes

et al. 2023

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“…On-surface synthesis under ultra-high-vacuum (UHV) conditions , has emerged as a powerful tool to construct one-dimensional π-conjugated oligomers on coinage metal supports, yielding coordination polymers, tailored GNRs with diverse topologies, and other forms of conjugated ladder polymers . This approach provides an alternative to the deposition of pre-synthesized oligomers on surfaces, − which are usually poorly soluble and too fragile for intact sublimation.…”

Section: Introductionmentioning

confidence: 99%

“…A wide variety of atomically precise GNRs and graphene nanoflakes have been synthesized on coinage metal surfaces, with the electronic structure defined by edge termination, topology, and width, ranging from metallic to semiconducting. ,− Incorporation of nonbenzenoid rings, well-known as defects in graphene, , provides further means to engineer GNR properties. Indeed, the on-surface synthesis of several atomically precise graphene nanostructures containing four- to eight-membered rings has been achieved through rational precursor design. ,− …”

Section: Introductionmentioning

confidence: 99%

“…On-surface synthesis under ultra-high-vacuum (UHV) conditions 1,2 has emerged as a powerful tool to construct onedimensional π-conjugated oligomers on coinage metal supports, yielding coordination polymers, 3 tailored GNRs with diverse topologies, 4 and other forms of conjugated ladder polymers. 5 This approach provides an alternative to the deposition of pre-synthesized oligomers on surfaces, 6−9 which are usually poorly soluble and too fragile for intact sublimation. Furthermore, metal surfaces introduce a two-dimensional confinement and catalytic activity to support polymerization and cyclodehydrogenation reactions and represent ideal platforms for atomic-scale characterization of the in situ synthesized nanostructures, e.g., by scanning probe microscopy.…”

Section: ■ Introductionmentioning

confidence: 99%

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On-Surface Synthesis of Rigid Benzenoid- and Nonbenzenoid-Coupled Porphyrin–Graphene Nanoribbon Hybrids

et al. 2022

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On-surface synthesis made the fabrication of extended, atomically precise π-conjugated nanostructures on solid supports possible, with graphene nanoribbons (GNRs) and porphyrin-derived oligomers standing out. To date, examples combining these two prominent material classes are scarce, even though the chemically versatile porphyrins and the atomistic details of the nanographene spacers promise an easy tunability of structural and functional properties of the resulting hybrid structures. Here, we report the on-surface synthesis of extended benzenoid- and nonbenzenoid-coupled porphyrin–graphene nanoribbon hybrids by sequential Ullmann-type and cyclodehydrogenation reactions of a tailored Zn(II) 5,15-bis(5-bromo-1-naphthyl)porphyrin (Por(BrNaph)2) precursor on Au(111) and Ag(111). Using bond-resolved noncontact atomic force microscopy (nc-AFM) and scanning tunneling microscopy (STM), we characterize the structures of reaction intermediates and products in detail and provide insight into the effects of the annealing protocol. We further demonstrate the stability and rigidity of the extended one-dimensional porphyrin–GNR oligomers by employing an STM-based manipulation procedure, which allows for spectroscopic measurement upon lifting.

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“…On-surface cyclodehydrogenation has been extensively used for the formation of six-membered rings ,− ,,,− and less frequently five-membered rings, − among others. ,,,− ,− However, we are particularly interested in performing a competitive study within the same molecular platform, that is, designing a nonplanar nanographene that combines fjord and cove regions and therefore could evolve by a cyclodehydrogenation reaction toward the formation of a new six- or a five-membered ring. For this purpose, we identified compound 1 as an ideal candidate for studying selective cyclization (Figure a).…”

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confidence: 99%

Sequential On-Surface Cyclodehydrogenation in a Nonplanar Nanographene

Zuzak,

Quiroga,

Engelund

et al. 2023

J. Phys. Chem. Lett.

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On-surface synthesis has emerged as an attractive method for the atomically precise synthesis of new molecular nanostructures, being complementary to the widespread approach based on solution chemistry. It has been particularly successful in the synthesis of graphene nanoribbons and nanographenes. In both cases, the target compound is often generated through cyclodehydrogenation reactions, leading to planarization and the formation of hexagonal rings. To improve the flexibility and tunability of molecular units, however, the incorporation of other, nonbenzenoid, subunits is highly desirable. In this letter, we thoroughly analyze sequential cyclodehydrogenation reactions with a customdesigned molecular precursor. We demonstrate the step-by-step formation of hexagonal and pentagonal rings from the nonplanar precursor within fjord and cove regions, respectively. Computer models comprehensively support the experimental observations, revealing that both reactions imply an initial hydrogen abstraction and a final [1,2] hydrogen shift, but the formation of a pentagonal ring proceeds through a radical mechanism.

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On-surface synthesis of π-conjugated ladder-type polymers comprising nonbenzenoid moieties

Abstract: On-surface synthesis provides a powerful approach toward the fabrication of π-conjugated ladder polymers (CLPs). The synthesis of nonbenzenoid CLPs is achieved following two activation steps, including the formation of an intermediate 1D polymer.

Cited by 6 publications

References 46 publications

On-surface synthesis of non-benzenoid conjugated polymers by selective atomic rearrangement of ethynylarenes

On-surface synthesis of non-benzenoid conjugated polymers by selective atomic rearrangement of ethynylarenes

On-Surface Synthesis of Rigid Benzenoid- and Nonbenzenoid-Coupled Porphyrin–Graphene Nanoribbon Hybrids

Sequential On-Surface Cyclodehydrogenation in a Nonplanar Nanographene

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