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Abstract 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 ofV.+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 inCBPQN2(.+)suitable for binding twoMV.+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 twoMV.+in MeCN at room temperature. The formation of the tetrakisradical tetracationic inclusion complex — namely, [(MV)2⊂CBPQN]4(.+)– in MeCN was confirmed by VT1H 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 differentV.+, suggesting that localization of the radical‐pairing interactions has a strong influence on the packing of the twoMV.+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.
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This content will become publicly available on January 6, 2026
Electrifying P(V): Access to Polar and Radical Reactivity
Electrochemical, fully stereoselective P(V)‐radical hydrophosphorylation of olefins and carbonyl compounds using a P(V) reagent is disclosed. By strategically selecting the anode material, radical reactivity is accessible for alkene hydrophosphorylation whereas a polar pathway operates for ketone hydrophosphorylation. The mechanistic intricacies of these chemoselective transformations were explored in‐depth.
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- Award ID(s):
- 2002158
- PAR ID:
- 10565748
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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