Kinetically blocked stable heptazethrene and octazethrene

Closed-shell or open-shell in the ground state?

Yuan Li, Wee Kuan Heng, Byung Sun Lee, Naoki Aratani, José L. Zafra, Nina Bao, Richmond Lee, Young Mo Sung, Zhe Sun, Kuo Wei Huang, Richard D. Webster, Juan T. López Navarrete, Dongho Kim, Atsuhiro Osuka, Juan Casado, Jun Ding, Jishan Wu

Research output: Contribution to journalArticle

156 Citations (Scopus)

Abstract

Polycyclic aromatic hydrocarbons with an open-shell singlet biradical ground state are of fundamental interest and have potential applications in materials science. However, the inherent high reactivity makes their synthesis and characterization very challenging. In this work, a convenient synthetic route was developed to synthesize two kinetically blocked heptazethrene (HZ-TIPS) and octazethrene (OZ-TIPS) compounds with good stability. Their ground-state electronic structures were systematically investigated by a combination of different experimental methods, including steady-state and transient absorption spectroscopy, variable temperature NMR, electron spin resonance (ESR), superconducting quantum interfering device (SQUID), FT Raman, and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. All these demonstrated that the heptazethrene derivative HZ-TIPS has a closed-shell ground state while its octazethrene analogue OZ-TIPS with a smaller energy gap exists as an open-shell singlet biradical with a large measured biradical character (y = 0.56). Large two-photon absorption (TPA) cross sections (σ(2)) were determined for HZ-TIPS (σ(2)max = 920 GM at 1250 nm) and OZ-TIPS (σ(2)max = 1200 GM at 1250 nm). In addition, HZ-TIPS and OZ-TIPS show a closely stacked 1D polymer chain in single crystals.

Original languageEnglish
Pages (from-to)14913-14922
Number of pages10
JournalJournal of the American Chemical Society
Volume134
Issue number36
DOIs
Publication statusPublished - 2012 Sep 12

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Ground state
Polycyclic Aromatic Hydrocarbons
Electron Spin Resonance Spectroscopy
Jurisprudence
Photons
Spectrum Analysis
Polymers
X-Rays
Materials science
Polycyclic aromatic hydrocarbons
Absorption spectroscopy
Equipment and Supplies
Temperature
Electronic structure
Density functional theory
Paramagnetic resonance
Energy gap
Nuclear magnetic resonance
Single crystals
Derivatives

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Li, Yuan ; Heng, Wee Kuan ; Lee, Byung Sun ; Aratani, Naoki ; Zafra, José L. ; Bao, Nina ; Lee, Richmond ; Sung, Young Mo ; Sun, Zhe ; Huang, Kuo Wei ; Webster, Richard D. ; López Navarrete, Juan T. ; Kim, Dongho ; Osuka, Atsuhiro ; Casado, Juan ; Ding, Jun ; Wu, Jishan. / Kinetically blocked stable heptazethrene and octazethrene : Closed-shell or open-shell in the ground state?. In: Journal of the American Chemical Society. 2012 ; Vol. 134, No. 36. pp. 14913-14922.
@article{473e5a6e55d842e6adb43a66602e7c4e,
title = "Kinetically blocked stable heptazethrene and octazethrene: Closed-shell or open-shell in the ground state?",
abstract = "Polycyclic aromatic hydrocarbons with an open-shell singlet biradical ground state are of fundamental interest and have potential applications in materials science. However, the inherent high reactivity makes their synthesis and characterization very challenging. In this work, a convenient synthetic route was developed to synthesize two kinetically blocked heptazethrene (HZ-TIPS) and octazethrene (OZ-TIPS) compounds with good stability. Their ground-state electronic structures were systematically investigated by a combination of different experimental methods, including steady-state and transient absorption spectroscopy, variable temperature NMR, electron spin resonance (ESR), superconducting quantum interfering device (SQUID), FT Raman, and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. All these demonstrated that the heptazethrene derivative HZ-TIPS has a closed-shell ground state while its octazethrene analogue OZ-TIPS with a smaller energy gap exists as an open-shell singlet biradical with a large measured biradical character (y = 0.56). Large two-photon absorption (TPA) cross sections (σ(2)) were determined for HZ-TIPS (σ(2)max = 920 GM at 1250 nm) and OZ-TIPS (σ(2)max = 1200 GM at 1250 nm). In addition, HZ-TIPS and OZ-TIPS show a closely stacked 1D polymer chain in single crystals.",
author = "Yuan Li and Heng, {Wee Kuan} and Lee, {Byung Sun} and Naoki Aratani and Zafra, {Jos{\'e} L.} and Nina Bao and Richmond Lee and Sung, {Young Mo} and Zhe Sun and Huang, {Kuo Wei} and Webster, {Richard D.} and {L{\'o}pez Navarrete}, {Juan T.} and Dongho Kim and Atsuhiro Osuka and Juan Casado and Jun Ding and Jishan Wu",
year = "2012",
month = "9",
day = "12",
doi = "10.1021/ja304618v",
language = "English",
volume = "134",
pages = "14913--14922",
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Li, Y, Heng, WK, Lee, BS, Aratani, N, Zafra, JL, Bao, N, Lee, R, Sung, YM, Sun, Z, Huang, KW, Webster, RD, López Navarrete, JT, Kim, D, Osuka, A, Casado, J, Ding, J & Wu, J 2012, 'Kinetically blocked stable heptazethrene and octazethrene: Closed-shell or open-shell in the ground state?', Journal of the American Chemical Society, vol. 134, no. 36, pp. 14913-14922. https://doi.org/10.1021/ja304618v

Kinetically blocked stable heptazethrene and octazethrene : Closed-shell or open-shell in the ground state? / Li, Yuan; Heng, Wee Kuan; Lee, Byung Sun; Aratani, Naoki; Zafra, José L.; Bao, Nina; Lee, Richmond; Sung, Young Mo; Sun, Zhe; Huang, Kuo Wei; Webster, Richard D.; López Navarrete, Juan T.; Kim, Dongho; Osuka, Atsuhiro; Casado, Juan; Ding, Jun; Wu, Jishan.

In: Journal of the American Chemical Society, Vol. 134, No. 36, 12.09.2012, p. 14913-14922.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Kinetically blocked stable heptazethrene and octazethrene

T2 - Closed-shell or open-shell in the ground state?

AU - Li, Yuan

AU - Heng, Wee Kuan

AU - Lee, Byung Sun

AU - Aratani, Naoki

AU - Zafra, José L.

AU - Bao, Nina

AU - Lee, Richmond

AU - Sung, Young Mo

AU - Sun, Zhe

AU - Huang, Kuo Wei

AU - Webster, Richard D.

AU - López Navarrete, Juan T.

AU - Kim, Dongho

AU - Osuka, Atsuhiro

AU - Casado, Juan

AU - Ding, Jun

AU - Wu, Jishan

PY - 2012/9/12

Y1 - 2012/9/12

N2 - Polycyclic aromatic hydrocarbons with an open-shell singlet biradical ground state are of fundamental interest and have potential applications in materials science. However, the inherent high reactivity makes their synthesis and characterization very challenging. In this work, a convenient synthetic route was developed to synthesize two kinetically blocked heptazethrene (HZ-TIPS) and octazethrene (OZ-TIPS) compounds with good stability. Their ground-state electronic structures were systematically investigated by a combination of different experimental methods, including steady-state and transient absorption spectroscopy, variable temperature NMR, electron spin resonance (ESR), superconducting quantum interfering device (SQUID), FT Raman, and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. All these demonstrated that the heptazethrene derivative HZ-TIPS has a closed-shell ground state while its octazethrene analogue OZ-TIPS with a smaller energy gap exists as an open-shell singlet biradical with a large measured biradical character (y = 0.56). Large two-photon absorption (TPA) cross sections (σ(2)) were determined for HZ-TIPS (σ(2)max = 920 GM at 1250 nm) and OZ-TIPS (σ(2)max = 1200 GM at 1250 nm). In addition, HZ-TIPS and OZ-TIPS show a closely stacked 1D polymer chain in single crystals.

AB - Polycyclic aromatic hydrocarbons with an open-shell singlet biradical ground state are of fundamental interest and have potential applications in materials science. However, the inherent high reactivity makes their synthesis and characterization very challenging. In this work, a convenient synthetic route was developed to synthesize two kinetically blocked heptazethrene (HZ-TIPS) and octazethrene (OZ-TIPS) compounds with good stability. Their ground-state electronic structures were systematically investigated by a combination of different experimental methods, including steady-state and transient absorption spectroscopy, variable temperature NMR, electron spin resonance (ESR), superconducting quantum interfering device (SQUID), FT Raman, and X-ray crystallographic analysis, assisted by unrestricted symmetry-broken density functional theory (DFT) calculations. All these demonstrated that the heptazethrene derivative HZ-TIPS has a closed-shell ground state while its octazethrene analogue OZ-TIPS with a smaller energy gap exists as an open-shell singlet biradical with a large measured biradical character (y = 0.56). Large two-photon absorption (TPA) cross sections (σ(2)) were determined for HZ-TIPS (σ(2)max = 920 GM at 1250 nm) and OZ-TIPS (σ(2)max = 1200 GM at 1250 nm). In addition, HZ-TIPS and OZ-TIPS show a closely stacked 1D polymer chain in single crystals.

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