A periodic system of polycyclic aromatic hydrocarbons for predictive molecular growth processes
4 affiliations
- 1National Synchrotron Radiation Laboratory, University of Science and Technology of China Hefei Anhui 230029 China
- 2School of New Energy Engineering, Hefei Institute of Technology Hefei Anhui 238076 China
- 3Department of Chemistry, University of Hawaii at Manoa Honolulu HI 96822 USA
- 4School of Nuclear Science and Technology, University of Science and Technology of China Hefei Anhui 230027 China
Abstract
Radical–radical reactions of resonantly stabilized species such as propargyl (C3H3˙) and benzyl (C7H7˙) efficiently generate polycyclic aromatic hydrocarbons (PAHs). Key mechanisms—propargyl addition–benzannulation (PABA), methyl addition–ring expansion (MARE), and cyclopentadienyl addition–naphthylization (CPAN)—govern early-stage aromatic growth, but transforming these mechanisms to larger PAHs is computationally challenging due to combinatorial intermediates and reactions on excited state triplet surfaces. Here, we introduce a “periodic system” of PAHs that organizes aromatic growth according to transferable radical–radical motifs, enabling prediction of molecular evolution across the size regime. Using (2-naphthyl)-methyl (2-C11H9˙) and benzyl (C7H7˙) radicals as benchmarks, we experimentally demonstrate the predicted gas-phase formation of four- and five-ring PAHs, including (1) C18H12 isomers: tetracene, benz[a]anthracene, and [4]helicene; (2) C22H14 isomers: benzo[a]tetracene, benzo[a]tetraphene, and [5]helicene. Secondary hydrogen-loss and successive reactions produce even larger 2D and 3D aromatics, such as nanobowls and fullerenes, and their building blocks (corannulene and coronene). This framework provides a unifying and predictive description of PAH growth across combustion and circumstellar environments such as carbon-rich envelopes of late-type Asymptotic Giant Branch (AGB) stars and planetary nebulae.
Related
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- Extensive TD-DFT investigation of the absorption wavelength in single and multilayer polycyclic aromatic hydrocarbons/graphene quantum carbon dots
- Mechanochemical Birch Reductive Alkylation of Polycyclic Aromatic Hydrocarbons
- Cyclization of a 1,8‐Diphenylanthracene by Scholl Reactions to Form Five‐ and Seven‐Membered Ring Embedded Polycyclic Aromatic Hydrocarbons
- Synthesis of silylated polycyclic aromatic hydrocarbons by lithium-mediated mechanochemical Birch reductive silylation† † Dedicated to the memory of Dr Kazuhiko Sato at the National Institute of Advanced Industrial Science and Technology (AIST), Japan, in recognition of his outstanding contributions to silicon chemistry and catalysis, and in mourning of his untimely passing.
BibTeX
@article{li2026periodic,
title = {{A periodic system of polycyclic aromatic hydrocarbons for predictive molecular growth processes}},
author = {Wang Li and Hu Ju and Ming-Gao Xu and Shane J. Goettl and Jiu-Zhong Yang and Long Zhao and Ralf I. Kaiser},
journal = {Chemical Science},
year = {2026},
month = sep,
doi = {10.1039/d6sc05859k},
url = {https://doi.org/10.1039/d6sc05859k},
note = {CC BY-NC 3.0},
}
RIS
TY - JOUR
TI - A periodic system of polycyclic aromatic hydrocarbons for predictive molecular growth processes
AU - Wang Li
AU - Hu Ju
AU - Ming-Gao Xu
AU - Shane J. Goettl
AU - Jiu-Zhong Yang
AU - Long Zhao
AU - Ralf I. Kaiser
PY - 2026
DA - 2026/09/07
JO - Chemical Science
DO - 10.1039/d6sc05859k
UR - https://doi.org/10.1039/d6sc05859k
AB - Radical–radical reactions of resonantly stabilized species such as propargyl (C3H3˙) and benzyl (C7H7˙) efficiently generate polycyclic aromatic hydrocarbons (PAHs). Key mechanisms—propargyl addition–benzannulation (PABA), methyl addition–ring expansion (MARE), and cyclopentadienyl addition–naphthylization (CPAN)—govern early-stage aromatic growth, but transforming these mechanisms to larger PAHs is computationally challenging due to combinatorial intermediates and reactions on excited state triplet surfaces. Here, we introduce a “periodic system” of PAHs that organizes aromatic growth according to transferable radical–radical motifs, enabling prediction of molecular evolution across the size regime. Using (2-naphthyl)-methyl (2-C11H9˙) and benzyl (C7H7˙) radicals as benchmarks, we experimentally demonstrate the predicted gas-phase formation of four- and five-ring PAHs, including (1) C18H12 isomers: tetracene, benz[a]anthracene, and [4]helicene; (2) C22H14 isomers: benzo[a]tetracene, benzo[a]tetraphene, and [5]helicene. Secondary hydrogen-loss and successive reactions produce even larger 2D and 3D aromatics, such as nanobowls and fullerenes, and their building blocks (corannulene and coronene). This framework provides a unifying and predictive description of PAH growth across combustion and circumstellar environments such as carbon-rich envelopes of late-type Asymptotic Giant Branch (AGB) stars and planetary nebulae.
SN - 2041-6520
SN - 2041-6539
ER -