Pushing Extended p-Quinodimethanes to the Limit: Stable Tetracyano-oligo(N-annulated perylene)quinodimethanes with Tunable Ground States

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• 作者：Zebing Zeng ; Masatoshi Ishida ; Jos茅 L. Zafra ; Xiaojian Zhu ; Young Mo Sung ; Nina Bao ; Richard D. Webster ; Byung Sun Lee ; Run-Wei Li ; Wangdong Zeng ; Yuan Li ; Chunyan Chi ; Juan T. L贸pez Navarrete ; Jun Ding ; Juan Casado ; Dongho Kim ; Jishan Wu
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：April 24, 2013
• 年：2013
• 卷：135
• 期：16
• 页码：6363-6371
• 全文大小：600K
• 年卷期：v.135,no.16(April 24, 2013)
• ISSN：1520-5126

文摘

p-Quinodimethane (p-QDM) is a fundamental building block for the design of 蟺-conjugated systems with low band gap and open-shell biradical character. However, synthesis of extended p-QDMs has usually suffered from their intrinsic high reactivity and poor solubility. In this work, benzannulation together with terminal cyano-substitution was demonstrated to be an efficient approach for the synthesis of a series of soluble and stable tetracyano-oligo(N-annulated perylene)quinodimethanes nPer-CN (n = 1鈥?), with the longest molecule having 12 para-linked benzenoid rings! The geometry and electronic structures of these oligomers were investigated by steady-state and transient absorption spectroscopy, nuclear magnetic resonance, electron spin resonance, superconducting quantum interference device, and FT Raman spectroscopy assisted by density functional theory calculations. They showed tunable ground states, varying from a closed-shell quinoidal structure for monomer, to a singlet biradical for dimer, trimer, and tetramer, and to a triplet biradical for pentamer and hexamer. Large two-photon absorption cross-section values were observed in the near-infrared range, which also exhibited a clear chain-length dependence.