Kinetically blocked stable heptazethrene and octazethrene: Closed-shell or open-shell in the ground state?

Yuan Li, WeeKuan Heng, Byungsun Lee, Naoki Aratani, José Luis Zafra, Nina Bao, Richmond Lee, Youngmo Sung, Zhe Sun, Kuo-Wei Huang, Richard D. Webster, Juan Teodomiro Lõpez Navarrete, Dongho Kim, Atsuhiro Osuka, Juan Casado, Jun Ding, Jishan Wu

Research output: Contribution to journalArticlepeer-review

236 Scopus citations

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. © 2012 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)14913-14922
Number of pages10
JournalJournal of the American Chemical Society
Volume134
Issue number36
DOIs
StatePublished - Aug 31 2012

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: J.W. acknowledges the financial support from the BMRC-NMRC grant (no. 10/1/21/19/642), MOE Tier 2 grant (MOE2011-T2-2-130), and A*STAR IMRE core funding (IMRE/10-1P0509). The work at Yonsei University was supported by WCU (World Class University) programs (R32-2010-10217-0) and an AFSOR/APARD grant (no. FA2386-09-1-4092). K.-W.H. acknowledges the financial support from KAUST. We thank Ji'En Wu and Yanhui Han for their kind assistance on the NMR analysis and Prof. Yuan-Chung Cheng for useful discussion.

ASJC Scopus subject areas

  • Biochemistry
  • Colloid and Surface Chemistry
  • General Chemistry
  • Catalysis

Fingerprint

Dive into the research topics of 'Kinetically blocked stable heptazethrene and octazethrene: Closed-shell or open-shell in the ground state?'. Together they form a unique fingerprint.
  • CCDC 875408: Experimental Crystal Structure Determination : [(1,9-dimethyl-1,3a,9,16c-tetrahydrodibenzo[de,op]pentacene-7,15-diyl)diethyne-2,1-diyl]bis[tri(propan-2-yl)silane]

    Li, Y. (Creator), Heng, W. (Creator), Lee, B. S. (Creator), Aratani, N. (Creator), Zafra, J. L. (Creator), Bao, N. (Creator), Lee, R. (Creator), Sung, Y. M. (Creator), Sun, Z. (Creator), Huang, K. (Creator), Webster, R. D. (Creator), Navarrete, J. T. L. (Creator), Kim, D. (Creator), Osuka, A. (Creator), Casado, J. (Creator), Ding, J. (Creator), Wu, J. (Creator), Li, Y. (Creator), Heng, W. (Creator), Lee, B. S. (Creator), Aratani, N. (Creator), Zafra, J. L. (Creator), Bao, N. (Creator), Lee, R. (Creator), Sung, Y. M. (Creator), Sun, Z. (Creator), Webster, R. D. (Creator), Navarrete, J. T. L. (Creator), Kim, D. (Creator), Osuka, A. (Creator), Casado, J. (Creator), Ding, J. (Creator), Wu, J. (Creator), Li, Y. (Creator), Heng, W. (Creator), Lee, B. S. (Creator), Aratani, N. (Creator), Zafra, J. L. (Creator), Bao, N. (Creator), Lee, R. (Creator), Sung, Y. M. (Creator), Sun, Z. (Creator), Webster, R. D. (Creator), Navarrete, J. T. L. (Creator), Kim, D. (Creator), Osuka, A. (Creator), Casado, J. (Creator), Ding, J. (Creator) & Wu, J. (Creator), Cambridge Crystallographic Data Centre, 2013

    Dataset

  • CCDC 875409: Experimental Crystal Structure Determination : (1,12-dihydrodibenzo[de,qr]hexacene-7,16-diyldiethyne-2,1-diyl)bis[tri(propan-2-yl)silane]

    Li, Y. (Creator), Heng, W. (Creator), Lee, B. S. (Creator), Aratani, N. (Creator), Zafra, J. L. (Creator), Bao, N. (Creator), Lee, R. (Creator), Sung, Y. M. (Creator), Sun, Z. (Creator), Huang, K. (Creator), Webster, R. D. (Creator), Navarrete, J. T. L. (Creator), Kim, D. (Creator), Osuka, A. (Creator), Casado, J. (Creator), Ding, J. (Creator), Wu, J. (Creator), Li, Y. (Creator), Heng, W. (Creator), Lee, B. S. (Creator), Aratani, N. (Creator), Zafra, J. L. (Creator), Bao, N. (Creator), Lee, R. (Creator), Sung, Y. M. (Creator), Sun, Z. (Creator), Webster, R. D. (Creator), Navarrete, J. T. L. (Creator), Kim, D. (Creator), Osuka, A. (Creator), Casado, J. (Creator), Ding, J. (Creator), Wu, J. (Creator), Li, Y. (Creator), Heng, W. (Creator), Lee, B. S. (Creator), Aratani, N. (Creator), Zafra, J. L. (Creator), Bao, N. (Creator), Lee, R. (Creator), Sung, Y. M. (Creator), Sun, Z. (Creator), Webster, R. D. (Creator), Navarrete, J. T. L. (Creator), Kim, D. (Creator), Osuka, A. (Creator), Casado, J. (Creator), Ding, J. (Creator) & Wu, J. (Creator), Cambridge Crystallographic Data Centre, 2013

    Dataset

Cite this