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Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization

[Image: see text] Incipient soot early in the flame was studied by high-resolution atomic force microscopy and scanning tunneling microscopy to resolve the atomic structure and orbital densities of single soot molecules prepared on bilayer NaCl on Cu(111). We resolved extended catacondensed and pent...

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Autores principales: Lieske, Leonard-Alexander, Commodo, Mario, Martin, Jacob W., Kaiser, Katharina, Benekou, Vasiliki, Minutolo, Patrizia, D’Anna, Andrea, Gross, Leo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2023
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10373522/
https://www.ncbi.nlm.nih.gov/pubmed/37436943
http://dx.doi.org/10.1021/acsnano.3c02194
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author Lieske, Leonard-Alexander
Commodo, Mario
Martin, Jacob W.
Kaiser, Katharina
Benekou, Vasiliki
Minutolo, Patrizia
D’Anna, Andrea
Gross, Leo
author_facet Lieske, Leonard-Alexander
Commodo, Mario
Martin, Jacob W.
Kaiser, Katharina
Benekou, Vasiliki
Minutolo, Patrizia
D’Anna, Andrea
Gross, Leo
author_sort Lieske, Leonard-Alexander
collection PubMed
description [Image: see text] Incipient soot early in the flame was studied by high-resolution atomic force microscopy and scanning tunneling microscopy to resolve the atomic structure and orbital densities of single soot molecules prepared on bilayer NaCl on Cu(111). We resolved extended catacondensed and pentagonal-ring linked (pentalinked) species indicating how small aromatics cross-link and cyclodehydrogenate to form moderately sized aromatics. In addition, we resolved embedded pentagonal and heptagonal rings in flame aromatics. These nonhexagonal rings suggest simultaneous growth through aromatic cross-linking/cyclodehydrogenation and hydrogen abstraction acetylene addition. Moreover, we observed three classes of open-shell π-radical species. First, radicals with an unpaired π-electron delocalized along the molecule’s perimeter. Second, molecules with partially localized π-electrons at zigzag edges of a π-radical. Third, molecules with strong localization of a π-electron at pentagonal- and methylene-type sites. The third class consists of π-radicals localized enough to enable thermally stable bonds, as well as multiradical species such as diradicals in the open-shell triplet state. These π-diradicals can rapidly cluster through barrierless chain reactions enhanced by van der Waals interactions. These results improve our understanding of soot formation and the products formed by combustion and could provide insights for cleaner combustion and the production of hydrogen without CO(2) emissions.
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spelling pubmed-103735222023-07-28 Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization Lieske, Leonard-Alexander Commodo, Mario Martin, Jacob W. Kaiser, Katharina Benekou, Vasiliki Minutolo, Patrizia D’Anna, Andrea Gross, Leo ACS Nano [Image: see text] Incipient soot early in the flame was studied by high-resolution atomic force microscopy and scanning tunneling microscopy to resolve the atomic structure and orbital densities of single soot molecules prepared on bilayer NaCl on Cu(111). We resolved extended catacondensed and pentagonal-ring linked (pentalinked) species indicating how small aromatics cross-link and cyclodehydrogenate to form moderately sized aromatics. In addition, we resolved embedded pentagonal and heptagonal rings in flame aromatics. These nonhexagonal rings suggest simultaneous growth through aromatic cross-linking/cyclodehydrogenation and hydrogen abstraction acetylene addition. Moreover, we observed three classes of open-shell π-radical species. First, radicals with an unpaired π-electron delocalized along the molecule’s perimeter. Second, molecules with partially localized π-electrons at zigzag edges of a π-radical. Third, molecules with strong localization of a π-electron at pentagonal- and methylene-type sites. The third class consists of π-radicals localized enough to enable thermally stable bonds, as well as multiradical species such as diradicals in the open-shell triplet state. These π-diradicals can rapidly cluster through barrierless chain reactions enhanced by van der Waals interactions. These results improve our understanding of soot formation and the products formed by combustion and could provide insights for cleaner combustion and the production of hydrogen without CO(2) emissions. American Chemical Society 2023-07-12 /pmc/articles/PMC10373522/ /pubmed/37436943 http://dx.doi.org/10.1021/acsnano.3c02194 Text en © 2023 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by-nc-nd/4.0/Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Lieske, Leonard-Alexander
Commodo, Mario
Martin, Jacob W.
Kaiser, Katharina
Benekou, Vasiliki
Minutolo, Patrizia
D’Anna, Andrea
Gross, Leo
Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization
title Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization
title_full Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization
title_fullStr Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization
title_full_unstemmed Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization
title_short Portraits of Soot Molecules Reveal Pathways to Large Aromatics, Five-/Seven-Membered Rings, and Inception through π-Radical Localization
title_sort portraits of soot molecules reveal pathways to large aromatics, five-/seven-membered rings, and inception through π-radical localization
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10373522/
https://www.ncbi.nlm.nih.gov/pubmed/37436943
http://dx.doi.org/10.1021/acsnano.3c02194
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