TY - JOUR
T1 - Radically Enhanced Dual Recognition
AU - Chen, Xiao Yang
AU - Mao, Haochuan
AU - Feng, Yuanning
AU - Cai, Kang
AU - Shen, Dengke
AU - Wu, Huang
AU - Zhang, Long
AU - Zhao, Xingang
AU - Chen, Hongliang
AU - Song, Bo
AU - Jiao, Yang
AU - Wu, Yong
AU - Stern, Charlotte L.
AU - Wasielewski, Michael R.
AU - Stoddart, J. Fraser
N1 - Funding Information:
Financial support from Northwestern University is gratefully acknowledged. This work was supported by the National Science Foundation under Award CHE‐1900422 (M.R.W.). The research made use of the IMSERC at Northwestern University, which has received support from the NIH (1S10OD012016‐01/ 1S10RR019071‐01A1), Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS‐1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN).
Funding Information:
Financial support from Northwestern University is gratefully acknowledged. This work was supported by the National Science Foundation under Award CHE-1900422 (M.R.W.). The research made use of the IMSERC at Northwestern University, which has received support from the NIH (1S10OD012016-01/ 1S10RR019071-01A1), Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN).
Publisher Copyright:
© 2021 Wiley-VCH GmbH
PY - 2021/11/22
Y1 - 2021/11/22
N2 - Complexation between a viologen radical cation (V.+) and cyclobis(paraquat-p-phenylene) diradical dication (CBPQT2(.+)) has been investigated and utilized extensively in the construction of mechanically interlocked molecules (MIMs) and artificial molecular machines (AMMs). The selective recognition of a pair of V.+ using radical-pairing interactions, however, remains a formidable challenge. Herein, we report the efficient encapsulation of two methyl viologen radical cations (MV.+) in a size-matched bisradical dicationic host — namely, cyclobis(paraquat-2,6-naphthalene)2(.+), i.e., CBPQN2(.+). Central to this dual recognition process was the choice of 2,6-bismethylenenaphthalene linkers for incorporation into the bisradical dicationic host. They provide the space between the two bipyridinium radical cations in CBPQN2(.+) suitable for binding two MV.+ with relatively short (3.05–3.25 Å) radical-pairing distances. The size-matched bisradical dicationic host was found to exhibit highly selective and cooperative association with the two MV.+ in MeCN at room temperature. The formation of the tetrakisradical tetracationic inclusion complex — namely, [(MV)2⊂CBPQN]4(.+) – in MeCN was confirmed by VT 1H NMR, as well as by EPR spectroscopy. The solid-state superstructure of [(MV)2⊂CBPQN]4(.+) reveals an uneven distribution of the binding distances (3.05, 3.24, 3.05 Å) between the three different V.+, suggesting that localization of the radical-pairing interactions has a strong influence on the packing of the two MV.+ inside the bisradical dicationic host. Our findings constitute a rare example of binding two radical guests with high affinity and cooperativity using host-guest radical-pairing interactions. Moreover, they open up possibilities of harnessing the tetrakisradical tetracationic inclusion complex as a new, orthogonal and redox-switchable recognition motif for the construction of MIMs and AMMs.
AB - Complexation between a viologen radical cation (V.+) and cyclobis(paraquat-p-phenylene) diradical dication (CBPQT2(.+)) has been investigated and utilized extensively in the construction of mechanically interlocked molecules (MIMs) and artificial molecular machines (AMMs). The selective recognition of a pair of V.+ using radical-pairing interactions, however, remains a formidable challenge. Herein, we report the efficient encapsulation of two methyl viologen radical cations (MV.+) in a size-matched bisradical dicationic host — namely, cyclobis(paraquat-2,6-naphthalene)2(.+), i.e., CBPQN2(.+). Central to this dual recognition process was the choice of 2,6-bismethylenenaphthalene linkers for incorporation into the bisradical dicationic host. They provide the space between the two bipyridinium radical cations in CBPQN2(.+) suitable for binding two MV.+ with relatively short (3.05–3.25 Å) radical-pairing distances. The size-matched bisradical dicationic host was found to exhibit highly selective and cooperative association with the two MV.+ in MeCN at room temperature. The formation of the tetrakisradical tetracationic inclusion complex — namely, [(MV)2⊂CBPQN]4(.+) – in MeCN was confirmed by VT 1H NMR, as well as by EPR spectroscopy. The solid-state superstructure of [(MV)2⊂CBPQN]4(.+) reveals an uneven distribution of the binding distances (3.05, 3.24, 3.05 Å) between the three different V.+, suggesting that localization of the radical-pairing interactions has a strong influence on the packing of the two MV.+ inside the bisradical dicationic host. Our findings constitute a rare example of binding two radical guests with high affinity and cooperativity using host-guest radical-pairing interactions. Moreover, they open up possibilities of harnessing the tetrakisradical tetracationic inclusion complex as a new, orthogonal and redox-switchable recognition motif for the construction of MIMs and AMMs.
KW - binding stoichiometry
KW - host-guest systems
KW - molecular recognition
KW - radical-pairing interactions
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U2 - 10.1002/anie.202109647
DO - 10.1002/anie.202109647
M3 - Article
C2 - 34342116
AN - SCOPUS:85114353167
VL - 60
SP - 25454
EP - 25462
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
SN - 1433-7851
IS - 48
ER -