Efficient photogeneration of nonacene on nanostructured graphene

G., Ayani, Cosme; Pisarra, M.; Urgel, José I.; Navarro, José María Martínez; Dı́az, Cristina; Hayashi, Hironobu; Yamada, Hiroko; Calleja, F.; Miranda, Rodolfo; Fasel, Román; Martı́n, Fernando; Parga, Amadeo L. Vázquez de

doi:10.1039/d1nh00184a

Cited by 10 publications

(6 citation statements)

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“…For instance, the on-surface synthesis of graphene nanoribbons (GNRs) 36 , the discovery of novel chemical reactions 35 , 37 , or the synthesis of carbon-based nanographenes with intriguing electronic properties 38 – 42 have contributed significantly toward the development of the on-surface chemistry toolbox. Particular attention has recently been paid to the synthesis and characterization of higher acenes on surfaces 43 – 49 , with the largest synthesized members being decacene 50 , undecacene 46 , and dodecacene 51 . Herein, the use of α-diketone-, epoxy- and hydrogen-protected acene precursors, which provide them with the required solubility and stability, followed by thermal or light-induced activation once deposited on the metal substrate, have typically been the synthesis strategies employed for the successful formation of pristine higher acenes.…”

Section: Introductionmentioning

confidence: 99%

On-surface synthesis and characterization of nitrogen-substituted undecacenes

et al. 2022

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Heteroatom substitution in acenes allows tailoring of their remarkable electronic properties, expected to include spin-polarization and magnetism for larger members of the acene family. Here, we present a strategy for the on-surface synthesis of three undecacene analogs substituted with four nitrogen atoms on an Au(111) substrate, by employing specifically designed diethano-bridged precursors. A similarly designed precursor is used to synthesize the pristine undecacene molecule. By comparing experimental features of scanning probe microscopy with ab initio simulations, we demonstrate that the ground state of the synthesized tetraazaundecacene has considerable open-shell character on Au(111). Additionally, we demonstrate that the electronegative nitrogen atoms induce a considerable shift in energy level alignment compared to the pristine undecacene, and that the introduction of hydro-aza groups causes local anti-aromaticity in the synthesized compounds. Our work provides access to the precise fabrication of nitrogen-substituted acenes and their analogs, potential building-blocks of organic electronics and spintronics, and a rich playground to explore π-electron correlation.

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Section: Introductionmentioning

confidence: 99%

On-surface synthesis and characterization of nitrogen-substituted undecacenes

et al. 2022

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“…Under this scenario, during the last decade oxidative ring-closure and cyclodehydrogenation reactions catalyzed on metal surfaces under ultra-high vacuum (UHV) conditions have emerged as an alternative approach toward the synthesis of open-shell NGs, which could not be obtained via conventional solution synthesis. In recent years, significant progress has resulted in the synthesis and characterization, via advanced scanning probe techniques, of members of the n-acene [17][18][19][20][21][22][23][24][25] and triangulene [26][27][28][29] families among others. [30][31][32][33][34] However, only the shorter members of the n-PA family such as 2-PA (perylene), [35] 3-PA (bisanthene), [36][37][38][39] 4-PA [40] and 5-PA (peri-pentacene), [41,42] together with heter-oatom-doped [43] and dibenzoperihexacene [44] derivatives, as well as several 1D carbon-based nanostructures containing n-PAs as building block units, [45][46][47][48][49] have been synthesized and characterized on metallic surfaces (see Scheme 1).…”

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Synthesis and Characterization of peri‐Heptacene on a Metallic Surface

et al. 2022

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The synthesis of long n-peri-acenes (n-PAs) is challenging as a result of their inherent open-shell radical character, which arises from the presence of parallel zigzag edges beyond a certain n value. They are considered as π-electron model systems to study magnetism in graphene nanostructures; being potential candidates in the fabrication of optoelectronic and spintronic devices. Here, we report the on-surface formation of the largest pristine member of the n-PA family, i.e. periheptacene (n = 7, 7-PA), obtained on an Au(111) substrate under ultra-high vacuum conditions. Our highresolution scanning tunneling microscopy investigations, complemented by theoretical simulations, provide insight into the chemical structure of this previously elusive compound. In addition, scanning tunneling spectroscopy reveals the antiferromagnetic open-shell singlet ground state of 7-PA, exhibiting singlet-triplet spin-flip inelastic excitations with an effective exchange coupling (J eff ) of 49 meV.

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“…During the last decade, on‐surface synthesis has emerged as a powerful and successful strategy toward the synthesis of carbon‐based nanomaterials such as nanographenes (NGs) [ 1 , 2 , 3 ] or 1D [ 4 , 5 , 6 ] and 2D π ‐conjugated polymers [ 7 , 8 ] that are frequently challenging to obtain in solution chemistry due to their high reactivity and/or low solubility. For instance, the recent synthesis of several members of the acene family [ 9 , 10 , 11 , 12 , 13 ] or acene‐based 1D polymers [ 14 , 15 ] supported on metal substrates has supposed a great progress in this field in view of their unique electronic, magnetic, and optical properties, with potential applications in organic (opto)electronics and spintronics. [ 16 , 17 ] Among the existing strategies to tune their remarkable properties, heteroatom substitution allows to tailor the topology of the π ‐conjugation by replacing CH groups from the carbon skeleton by N, B, P, or S atoms.…”

Section: Introductionmentioning

confidence: 99%

Surface‐Assisted Synthesis of N‐Containing π‐Conjugated Polymers

et al. 2022

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On-surface synthesis has recently emerged as a powerful strategy to design conjugated polymers previously precluded in conventional solution chemistry. Here, an N-containing pentacene-based precursor (tetraazapentacene) is ex-professo synthesized endowed with terminal dibromomethylene (:CBr 2 ) groups to steer homocoupling via dehalogenation on metallic supports. Combined scanning probe microscopy investigations complemented by theoretical calculations reveal how the substrate selection drives different reaction mechanisms. On Ag(111) the dissociation of bromine atoms at room temperature triggers the homocoupling of tetraazapentacene units together with the binding of silver adatoms to the nitrogen atoms of the monomers giving rise to a N-containing conjugated coordination polymer (P1). Subsequently, P1 undergoes ladderization at 200 °C, affording a pyrrolopyrrole-bridged conjugated polymer (P2). On Au(111) the formation of the intermediate polymer P1 is not observed and, instead, after annealing at 100 °C, the conjugated ladder polymer P2 is obtained, revealing the crucial role of metal adatoms on Ag(111) as compared to Au(111). Finally, on Ag(100) the loss of :CBr2 groups affords the formation of tetraazapentacene monomers, which coexist with polymer P1. Our results contribute to introduce protocols for the synthesis of N-containing conjugated polymers, illustrating the selective role of the metallic support in the underlying reaction mechanisms.

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Efficient photogeneration of nonacene on nanostructured graphene

Abstract: The on-surface photogeneration of nonacenes from α-bisdiketone precursors deposited on nanostructured epitaxial graphene grown on Ru(0001) has been studied by means of low temperature scanning tunneling microscopy and spectroscopy. The...

Cited by 10 publications

References 56 publications

On-surface synthesis and characterization of nitrogen-substituted undecacenes

On-surface synthesis and characterization of nitrogen-substituted undecacenes

Synthesis and Characterization of peri‐Heptacene on a Metallic Surface

Surface‐Assisted Synthesis of N‐Containing π‐Conjugated Polymers

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