A series of zigzag-edged polycyclic aromatic hydrocarbons (PAHs) (Z1-Z3) were synthesized from 2,12-dibromo-7,14-diphenyl-benzo[m]tetraphene (9) as a versatile building block. Their structures were unambiguously confirmed by laser desorption/ionization time-of-flight mass spectrometry, H NMR, Raman, and Fourier-transformed infrared (FTIR) spectroscopies as well as scanning tunneling microscopy. The fingerprint vibrational modes were elucidated with theoretical support. The edge- and size-dependent optical properties were characterized by UV-Vis absorption and fluorescence spectroscopy and DFT calculations. Moreover, ultrafast transient absorption spectroscopy revealed distinct modulation of the photophysical properties upon π-extension from Z1 to Z2, the latter having a gulf edge.
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http://dx.doi.org/10.1002/chem.202203981 | DOI Listing |
Chemistry
December 2024
Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan, 44919, Republic of Korea.
Nanographenes and polycyclic aromatic hydrocarbons, both finite forms of graphene, are promising organic semiconducting materials because their optoelectronic and magnetic properties can be modulated through precise control of their molecular peripheries. Several atomically precise edge structures have been prepared by bottom-up synthesis; however, no systematic elucidation of these edge topologies at the molecular level has been reported. Herein, we describe rationally designed modular syntheses of isomeric dibenzoixenes with diverse molecular peripheries, including cove, zigzag, bay, fjord, and gulf structured.
View Article and Find Full Text PDFChemistry
January 2025
Département de Chimie and Centre de Recherche sur les Matériaux Avancés (CERMA), Université Laval, Pavillon A.-Vachon, 1045 Ave de la Médecine, Québec, G1 V 0 A6, Canada E-mail.
Organic dyes are interesting building blocks for the preparation of organic semiconductors as they possess synthetic handles that can be used to functionalize them and, consequently, change their electronic properties. However, reactions to extend their π-conjugated framework through ring annulation have only been scarcely tested. Herein, we report the use of alkyne benzannulation on 2,8-dibromo-dibenzo[def,mno]chrysene (vat orange 3) and 2,9-dibromo-dibenzo[b,def]chrysene (vat orange 1) to extend the conjugation and reduce their bandgap.
View Article and Find Full Text PDFA series of zigzag-edged polycyclic aromatic hydrocarbons (PAHs) (Z1-Z3) were synthesized from 2,12-dibromo-7,14-diphenyl-benzo[m]tetraphene (9) as a versatile building block. Their structures were unambiguously confirmed by laser desorption/ionization time-of-flight mass spectrometry, H NMR, Raman, and Fourier-transformed infrared (FTIR) spectroscopies as well as scanning tunneling microscopy. The fingerprint vibrational modes were elucidated with theoretical support.
View Article and Find Full Text PDFChem Rev
July 2022
Department of Chemical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur 741246, India.
Phenalenyl, a zigzag-edged odd alternant hydrocarbon unit can be found in the graphene nanosheet. Hückel molecular orbital calculations indicate the presence of a nonbonding molecular orbital (NBMO), which originates from the linear combination of atomic orbitals (LCAO) arising from 13 carbon atoms of the phenalenyl molecule. Three redox states (cationic, neutral radical, and anionic) of the phenalenyl-based molecules were attributed to the presence of this NBMO.
View Article and Find Full Text PDFOrg Lett
November 2021
School of Chemistry and Chemical Engineering, Inner Mongolia University, 235 West University Street, Hohhot 010021, China.
Ovalene's nitrogenated derivative with all zigzag edges and nitrogen atom doping at the periphery has been developed via one-step nitrogenation of formylbisanthene. Because of nitrogen incorporation, these molecules show greatly decreased highest occupied molecular orbital levels, enhanced intermolecular interactions, and a reversible acid response. Aza-ovalene also exhibits a diatropic ring current along the periphery.
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