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Chen X, Chen H, Fraser Stoddart J. The Story of the Little Blue Box: A Tribute to Siegfried Hünig. Angew Chem Int Ed Engl 2023; 62:e202211387. [PMID: 36131604 PMCID: PMC10099103 DOI: 10.1002/anie.202211387] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Indexed: 02/02/2023]
Abstract
The tetracationic cyclophane, cyclobis(paraquat-p-phenylene), also known as the little blue box, constitutes a modular receptor that has facilitated the discovery of many host-guest complexes and mechanically interlocked molecules during the past 35 years. Its versatility in binding small π-donors in its tetracationic state, as well as forming trisradical tricationic complexes with viologen radical cations in its doubly reduced bisradical dicationic state, renders it valuable for the construction of various stimuli-responsive materials. Since the first reports in 1988, the little blue box has been featured in over 500 publications in the literature. All this research activity would not have been possible without the seminal contributions carried out by Siegfried Hünig, who not only pioneered the syntheses of viologen-containing cyclophanes, but also revealed their rich redox chemistry in addition to their ability to undergo intramolecular π-dimerization. This Review describes how his pioneering research led to the design and synthesis of the little blue box, and how this redox-active host evolved into the key component of molecular shuttles, switches, and machines.
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Affiliation(s)
- Xiao‐Yang Chen
- Department of ChemistryNorthwestern University2145 Sheridan RoadEvanstonIllinois 60208USA
| | - Hongliang Chen
- Stoddart Institute of Molecular ScienceDepartment of ChemistryZhejiang UniversityHangzhou310027China
- ZJU-Hangzhou Global Scientific and Technological Innovation CenterHangzhou311215China
| | - J. Fraser Stoddart
- Department of ChemistryNorthwestern University2145 Sheridan RoadEvanstonIllinois 60208USA
- Stoddart Institute of Molecular ScienceDepartment of ChemistryZhejiang UniversityHangzhou310027China
- ZJU-Hangzhou Global Scientific and Technological Innovation CenterHangzhou311215China
- School of ChemistryUniversity of New South WalesSydneyNSW 2052Australia
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Chen X, Mao H, Feng Y, Cai K, Shen D, Wu H, Zhang L, Zhao X, Chen H, Song B, Jiao Y, Wu Y, Stern CL, Wasielewski MR, Stoddart JF. Radically Enhanced Dual Recognition. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiao‐Yang Chen
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Haochuan Mao
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- Institute for Sustainability and Energy at Northwestern Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Yuanning Feng
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Kang Cai
- Department of Chemistry Nankai University 94 Weijin Road, Nankai District Tianjin 300071 China
| | - Dengke Shen
- Institutes of Physical Science and Information Technology Anhui University Hefei 230601 China
| | - Huang Wu
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Long Zhang
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Xingang Zhao
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Hongliang Chen
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Bo Song
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Yang Jiao
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Yong Wu
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Charlotte L. Stern
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Michael R. Wasielewski
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- Institute for Sustainability and Energy at Northwestern Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - J. Fraser Stoddart
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
- Stoddart Institute of Molecular Science Department of Chemistry Zhejiang University Hangzhou 310027 China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center Hangzhou 311215 China
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Chen XY, Mao H, Feng Y, Cai K, Shen D, Wu H, Zhang L, Zhao X, Chen H, Song B, Jiao Y, Wu Y, Stern CL, Wasielewski MR, Stoddart JF. Radically Enhanced Dual Recognition. Angew Chem Int Ed Engl 2021; 60:25454-25462. [PMID: 34342116 DOI: 10.1002/anie.202109647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Indexed: 11/08/2022]
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 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 1 H 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.
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Affiliation(s)
- Xiao-Yang Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Haochuan Mao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.,Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Yuanning Feng
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Kang Cai
- Department of Chemistry, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, China
| | - Dengke Shen
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Huang Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Long Zhang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Xingang Zhao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Hongliang Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Bo Song
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Yang Jiao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Yong Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Charlotte L Stern
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.,Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - J Fraser Stoddart
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.,School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia.,Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, 311215, China
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Jiao T, Qu H, Tong L, Cao X, Li H. A Self-Assembled Homochiral Radical Cage with Paramagnetic Behaviors. Angew Chem Int Ed Engl 2021; 60:9852-9858. [PMID: 33651476 DOI: 10.1002/anie.202100655] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/14/2021] [Indexed: 12/24/2022]
Abstract
Condensation of an inherently C3 -symmetric polychlorotriphenylmethyl (PTM) radical trisaldehyde with tris(2-aminoethyl)amine (TREN) yields a [4+4] tetrahedral radical cage as a racemic pair of homochiral enantiomers in 75 % isolated yield. The structure was characterized by X-ray crystallography, confirming the homochirality of each cage framework. The homochirality results from intramolecular [CH⋅⋅⋅π] and hydrogen-bonding interactions within the cage framework. The four PTM radicals in a cage undergo weak through-space coupling. Magnetic measurements demonstrated that each cage bears 3.58 spins.
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Affiliation(s)
- Tianyu Jiao
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Hang Qu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Lu Tong
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Xiaoyu Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Hao Li
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, P. R. China
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