Skeletal Editing of Cycloparaphenylenes by Direct Oxygen Insertion
8 affiliations
- 1Department of Chemistry, Graduate School of Science
- 2Nagoya University
- 3RIKEN Pioneering Research Institute
- 4RIKEN Center for Sustainable Resource Science
- 5Graduate School of Engineering
- 6University of Tokyo
- 7Institute of Transformative Bio-Molecules (WPI-ITbM
- 8Institute for Advanced Research, Nagoya University
Abstract
Direct modification of the carbon framework of cycloparaphenylenes (CPPs) remains challenging despite the substantial strain stored in these carbon nanorings. Here, we report two complementary chemical methods for inserting an oxygen atom into a C–C bond of pristine [n]CPPs and the methylene-bridged [6]CPP ([6]MCPP) to give the corresponding oxylene derivatives. Treatment with m-chloroperbenzoic acid and copper(II) acetylacetonate affords mono-oxygenated products from [6]–[9]CPP in modest yields. Photocatalytically generated singlet oxygen is more efficient for smaller, more strained nanorings: [6]MCPP is converted to [6]MCPP-oxylene in 58% yield within 0.5 h, whereas the reactivity decreases sharply with increasing CPP size. Density functional theory calculations reveal that oxygen-insertion enthalpies become progressively less exothermic with increasing ring size and correlate linearly with 1/n, providing a thermodynamic context for the observed ring-size dependence. X-ray crystallography and strain analysis further reveal that oxygen insertion redistributes strain across the ring and lowers molecular symmetry. The resulting CPPoxylenes show markedly altered photophysical properties, with [9]CPP-oxylene reaching ΦF = 0.91. Prolonged photocatalysis of [6]MCPP enables a second, regioselective oxygen insertion at the most highly strained remaining C–C bond of the mono-oxylene framework. The resulting dioxylene adopts a more elongated structure and emits blue fluorescence at 414 nm with ΦF = 0.39; timeresolved measurements show that the higher fluorescence efficiency arises primarily from suppression of nonradiative decay. These results establish direct oxygen insertion as a route to skeletal editing of CPPs and connect sequential editing with changes in strain distribution, molecular geometry, and photophysical behavior.
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BibTeX
@misc{kato2026skeletal,
title = {{Skeletal Editing of Cycloparaphenylenes by Direct Oxygen Insertion}},
author = {Tomoki Kato and Siyuan Ye and Hideya Kono and Tsubasa Okumura and Hiroki Shudo and Atsushi Usami and Kazuma Amaike and Akiko Yagi and Kenichiro Itami},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010364/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010364/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Skeletal Editing of Cycloparaphenylenes by Direct Oxygen Insertion
AU - Tomoki Kato
AU - Siyuan Ye
AU - Hideya Kono
AU - Tsubasa Okumura
AU - Hiroki Shudo
AU - Atsushi Usami
AU - Kazuma Amaike
AU - Akiko Yagi
AU - Kenichiro Itami
PY - 2026
DA - 2026/10/13
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010364/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010364/v1
AB - Direct modification of the carbon framework of cycloparaphenylenes (CPPs) remains challenging despite the substantial strain stored in these carbon nanorings. Here, we report two complementary chemical methods for inserting an oxygen atom into a C–C bond of pristine [n]CPPs and the methylene-bridged [6]CPP ([6]MCPP) to give the corresponding oxylene derivatives. Treatment with m-chloroperbenzoic acid and copper(II) acetylacetonate affords mono-oxygenated products from [6]–[9]CPP in modest yields. Photocatalytically generated singlet oxygen is more efficient for smaller, more strained nanorings: [6]MCPP is converted to [6]MCPP-oxylene in 58% yield within 0.5 h, whereas the reactivity decreases sharply with increasing CPP size. Density functional theory calculations reveal that oxygen-insertion enthalpies become progressively less exothermic with increasing ring size and correlate linearly with 1/n, providing a thermodynamic context for the observed ring-size dependence. X-ray crystallography and strain analysis further reveal that oxygen insertion redistributes strain across the ring and lowers molecular symmetry. The resulting CPPoxylenes show markedly altered photophysical properties, with [9]CPP-oxylene reaching ΦF = 0.91. Prolonged photocatalysis of [6]MCPP enables a second, regioselective oxygen insertion at the most highly strained remaining C–C bond of the mono-oxylene framework. The resulting dioxylene adopts a more elongated structure and emits blue fluorescence at 414 nm with ΦF = 0.39; timeresolved measurements show that the higher fluorescence efficiency arises primarily from suppression of nonradiative decay. These results establish direct oxygen insertion as a route to skeletal editing of CPPs and connect sequential editing with changes in strain distribution, molecular geometry, and photophysical behavior.
ER -