On-Surface Synthesis of Porous Carbon Nanoribbons from Polymer Chains
We demonstrate the on-surface synthesis of porous carbon nanoribbons on Ag(111) via a preprogrammed isomerization of conformationally flexible polymer chains followed by dehydrogenation reactions using thermal annealing. The carbon chains are fabricated by polymerization of prochiral 1,3,5-tris(3-b...
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Veröffentlicht in: | Journal of the American Chemical Society 2017-09, Vol.139 (37), p.12976-12984 |
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Hauptverfasser: | , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We demonstrate the on-surface synthesis of porous carbon nanoribbons on Ag(111) via a preprogrammed isomerization of conformationally flexible polymer chains followed by dehydrogenation reactions using thermal annealing. The carbon chains are fabricated by polymerization of prochiral 1,3,5-tris(3-bromophenyl)benzene (mTBPB) directly on the surface using an Ullmann-type reaction. At room temperature, mTBPB partially self-assembles in halogen-bonded 2D networks, which transform into organometallic chains and rings after debromination. The chain and ring formation is facilitated by conformational switching from a C 3h to Cs symmetry of mTBPB via rotation of m-phenylene units. The high conformational selectivity toward C s -conformers is templated by the twofold coordination to Ag adatoms. After thermally induced covalent-linking through aryl–aryl coupling, well-ordered nanoporous chains are created. Finally, the rotation of single phenylene units in combination with dehydrogenation cross-linking reactions within the polymer chains leads to the unexpected formation of porous carbon nanoribbons. We unveil the reaction mechanism in a low-temperature scanning tunneling microscopy study and demonstrate that the rotation of m-phenylene units is a powerful design tool to promote structural control in the synthesis of cyclic covalent organic nanostructures on metal surfaces. |
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ISSN: | 0002-7863 1520-5126 |
DOI: | 10.1021/jacs.7b04783 |