Stabilizing the Naphthalenediimide Radical within a Tetracationic Cyclophane

Tianyu Jiao, Kang Cai, Jordan N. Nelson, Yang Jiao, Yunyan Qiu, Guangcheng Wu, Jiawang Zhou, Chuyang Cheng, Dengke Shen, Yuanning Feng, Zhichang Liu, Michael R. Wasielewski*, J. Fraser Stoddart, Hao Li

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Organic radicals are of importance in developing smart materials that have paramagnetic and/or near-infrared optical properties. Their practical applications, however, are limited by the labile nature of the radicals. Here, we demonstrate that by using a tetracationic cyclophane, namely, cyclobis(4,4′-(1,4-phenylene)bispyridine-p-phenylene) (ExBox4+), to encapsulate a naphthalenediimide (NDI) guest, the redox properties of NDI can be modulated. In organic solvents such as MeCN or DMF, ExBox4+ is able to provide the surrounding Coulombic attraction to the NDI•- radical anion and therefore enhance its stability toward oxidation. In water, NDI•- is prone to dimerization, forming its (NDI•-)2 dimer. Under UV-light irradiation, the (NDI•-)2 dimer is observed to disproportionate and yield the dianionic NDI2-. ExBox4+ is able to encapsulate the NDI•- radical anion and prevent its dimerization, and as a consequence, the radical anion is protected from further reduction in a noncovalent manner. We believe that our strategy of modulating the redox properties of NDI by either host-guest recognition or mechanical interlocking can aid and abet the development of radical-based materials, which could be employed in pursuit of applications in many areas, such as transporting spin and charges.

Original languageEnglish (US)
Pages (from-to)16915-16922
Number of pages8
JournalJournal of the American Chemical Society
Issue number42
StatePublished - Oct 23 2019

ASJC Scopus subject areas

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


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