TY - JOUR
T1 - Stabilizing the Naphthalenediimide Radical within a Tetracationic Cyclophane
AU - Jiao, Tianyu
AU - Cai, Kang
AU - Nelson, Jordan N.
AU - Jiao, Yang
AU - Qiu, Yunyan
AU - Wu, Guangcheng
AU - Zhou, Jiawang
AU - Cheng, Chuyang
AU - Shen, Dengke
AU - Feng, Yuanning
AU - Liu, Zhichang
AU - Wasielewski, Michael R.
AU - Stoddart, J. Fraser
AU - Li, Hao
N1 - Funding Information:
This work was supported by the National Natural Science Foundation of China (No. 21772173, 91856116, and 21922108), the Natural Science Foundation of Zhejiang Province (No. LR18B020001), and “the Fundamental Research Funds for the Central Universities” (No.2019FZA3007). H.L. and T.J. also thank Zhejiang University for financial support. Z.L. acknowledges the financial support from the National Natural Science Foundation of China under Award Number 21971211. J.F.S. expresses appreciation to King Abdulaziz City for Science and Technology (KACST) and Northwestern University (NU) for support of this work. This work was also supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-SC0019356 (M.R.W., EPR spectroscopy). We thank Prof. Xin Hong (Department of Chemistry, Zhejiang University) for his help with computational resources used in this investigation.
PY - 2019/10/23
Y1 - 2019/10/23
N2 - 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.
AB - 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.
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U2 - 10.1021/jacs.9b08926
DO - 10.1021/jacs.9b08926
M3 - Article
C2 - 31533428
AN - SCOPUS:85073763810
VL - 141
SP - 16915
EP - 16922
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 42
ER -