Exploration of Interfacial Porphine Coupling Schemes and Hybrid Systems by Bond‐Resolved Scanning Probe Microscopy

Bischoff, Felix; He, Yuanqin; Riss, Alexander; Seufert, Knud; Auwärter, Willi; Barth, Johannes V.

doi:10.1002/ange.201808640

Cited by 5 publications

(5 citation statements)

References 64 publications

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“…In the context of surface science, investigations on intramolecular conformations, intermolecular coupling and supramolecular interactions of porphyrinoids have been performed in the last few years considering the interest of scientists from different fields in the study of such compounds adsorbed on well-defined interfaces. − While great efforts have been devoted to the systematic study of intramolecular conformations and noncovalent interactions containing different metals in the macrocycle and several peripheral-functionalized substituents; the intermolecular carbon–carbon (C–C) coupling of such compounds has been mainly limited to the fabrication of on-surface polymers and oligomers via the well-known Ullmann-like coupling − or dehydrogenative coupling, − among others. − However, further on-surface investigations of alternative chemical reactions with relevant implications in organic synthesis have remained unexplored. Among the novel on-surface reactions reported recently, the surface-catalyzed [3 + 3] cycloaromatization of isopropyl and isopropenyl substituents on arenes is of particular interest providing a novel pathway toward the fabrication of polymers that cannot be synthetized via conventional solution chemistry …”

Section: Introductionmentioning

confidence: 99%

Interplay between π-Conjugation and Exchange Magnetism in One-Dimensional Porphyrinoid Polymers

et al. 2022

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The synthesis of novel polymeric materials with porphyrinoid compounds as key components of the repeating units attracts widespread interest from several scientific fields in view of their extraordinary variety of functional properties with potential applications in a wide range of highly significant technologies. The vast majority of such polymers present a closed-shell ground state, and, only recently, as the result of improved synthetic strategies, the engineering of open-shell porphyrinoid polymers with spin delocalization along the conjugation length has been achieved. Here, we present a combined strategy toward the fabrication of one-dimensional porphyrinoid-based polymers homocoupled via surface-catalyzed [3 + 3] cycloaromatization of isopropyl substituents on Au(111). Scanning tunneling microscopy and noncontact atomic force microscopy describe the thermal-activated intra- and intermolecular oxidative ring closure reactions as well as the controlled tip-induced hydrogen dissociation from the porphyrinoid units. In addition, scanning tunneling spectroscopy measurements, complemented by computational investigations, reveal the open-shell character, that is, the antiferromagnetic singlet ground state (S = 0) of the formed polymers, characterized by singlet–triplet inelastic excitations observed between spins of adjacent porphyrinoid units. Our approach sheds light on the crucial relevance of the π-conjugation in the correlations between spins, while expanding the on-surface synthesis toolbox and opening avenues toward the synthesis of innovative functional nanomaterials with prospects in carbon-based spintronics.

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Section: Introductionmentioning

confidence: 99%

Interplay between π-Conjugation and Exchange Magnetism in One-Dimensional Porphyrinoid Polymers

et al. 2022

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“…On‐surface synthesis is the method of choice in order to achieve π‐conjugated conductive nanomeshes with red‐shifted absorption characteristics at the interface [28–30] . Polymerization protocols applied to porphyrin units that yield π‐extended covalent nanostructures are interconnection of activated dehalogenated precursors, [24, 31–38] Glaser coupling, [39] dehydrogenative [40–47] as well as defluorinative [48] coupling schemes, McMurry‐type [49] and Schiff‐base condensation [50] reactions.…”

Section: Introductionmentioning

confidence: 99%

Conservation of Nickel Ion Single‐Active Site Character in a Bottom‐Up Constructed π‐Conjugated Molecular Network

et al. 2022

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On-surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building-blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On-surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π-extended two-dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single-active site character of their single-molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom-up constructed covalent nanomeshes.

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“…To date, the formation of covalent tetrapyrrole–graphene heterostructures on surfaces has been mostly limited to fusing molecular tectons to GNRs through peripheral groups , and to the covalent attachment of porphyrins to graphene/GNR edges by temperature-induced dehydrogenation. , These procedures, however, do not provide high yields and distinct control over the product. This limitation can be overcome by employing specifically designed precursor molecules.…”

Section: Introductionmentioning

confidence: 99%

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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Exploration of Interfacial Porphine Coupling Schemes and Hybrid Systems by Bond‐Resolved Scanning Probe Microscopy

Cited by 5 publications

References 64 publications

Interplay between π-Conjugation and Exchange Magnetism in One-Dimensional Porphyrinoid Polymers

Interplay between π-Conjugation and Exchange Magnetism in One-Dimensional Porphyrinoid Polymers

Conservation of Nickel Ion Single‐Active Site Character in a Bottom‐Up Constructed π‐Conjugated Molecular Network

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

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