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Supramolecular Shish Kebabs: Higher Order Dimeric Structures from Ring‐in‐Rings Complexes with Conformational Adaptivity

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  • Institute for High Energy Physics, Chinese Academy of Sciences
  • Science China Press
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Abstract and Figures

Use of abiotic chemical systems for understanding higher order superstructures is challenging. Here we report a ring‐in‐ring(s) system comprising a hydrogen‐bonded macrocycle and cyclobis(paraquat‐o‐phenylene) tetracation (o‐Box) or cyclobis(paraquat‐p‐phenylene) tetracation (CBPQT⁴⁺, p‐Box) that assembles to construct discrete higher order structures with adaptive conformation. As indicated by mass spectrometry, computational modeling, NMR spectroscopy, and single‐crystal X‐ray diffraction analysis, this ring‐in‐ring(s) system features the box‐directed aggregation of multiple macrocycles, leading to generation of several stable species such as H4G (1 a/o‐Box) and H5G (1 a/o‐Box). Remarkably, a dimeric shish‐kebab‐like ring‐in‐rings superstructure H7G2 (1 a/o‐Box) or H8G2 (1 a/p‐Box) is formed from the coaxial stacking of two ring‐in‐rings units. The formation of such unique dimeric superstructures is attributed to the large π‐surface of this 2D planar macrocycle and the conformational variation of both host and guest.
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Host-Guest Systems
Supramolecular Shish Kebabs: Higher Order Dimeric Structures from
Ring-in-Rings Complexes with Conformational Adaptivity
Zhenwen Wang+, Lei Mei+, Chenxing Guo, Song Huang, Wei-Qun Shi, Xiaowei Li,
Wen Feng, Xiaopeng Li,* Cheng Yang,* and Lihua Yuan*
Abstract: Use of abiotic chemical systems for understanding higher order superstructures is challenging. Here we report
a ring-in-ring(s) system comprising a hydrogen-bonded macrocycle and cyclobis(paraquat-o-phenylene) tetracation
(o-Box) or cyclobis(paraquat-p-phenylene) tetracation (CBPQT4+,p-Box) that assembles to construct discrete higher
order structures with adaptive conformation. As indicated by mass spectrometry, computational modeling, NMR
spectroscopy, and single-crystal X-ray diffraction analysis, this ring-in-ring(s) system features the box-directed
aggregation of multiple macrocycles, leading to generation of several stable species such as H4G (1 a/o-Box) and H5G
(1a/o-Box). Remarkably, a dimeric shish-kebab-like ring-in-rings superstructure H7G2 (1 a/o-Box) or H8G2 (1 a/p-Box)
is formed from the coaxial stacking of two ring-in-rings units. The formation of such unique dimeric superstructures is
attributed to the large π-surface of this 2D planar macrocycle and the conformational variation of both host and guest.
Introduction
Noncovalent bonding interactions[1,2] and the hierarchical
assembly of biological structures[3] dictate almost every
essential process of life evolution. For instance, protein
dimerization occurs in a wide range of biological systems,
such as enzymes, transcription factors, integral membrane
receptors, and amyloid fibrils, all of which involve coopera-
tive noncovalent interactions between subunits.[4] The past
decades have witnessed great efforts towards elucidating the
structural features of dimerization and further oligomeriza-
tion into more sophisticated assemblies in biotic and abiotic
systems since these structures play a vital role in executing
functions, e.g., improved stability, and for the manipulation
of the accessibility and specificity of active sites.[5–8] Disclos-
ing the mystery of higher order architecture and achieving
precise control over self-assembly still represent an ongoing
challenge in supramolecular chemistry. Despite the signifi-
cant gap in complexity between biomolecules and non-
natural systems,[9,10] this challenging issue might be ad-
dressed nowadays by tailoring existing chemical systems and
designing novel complex assemblies. Ring-in-ring systems
based on host–guest recognition are one of the options
owing to their intriguing topology and demonstrated power
in constructing a variety of supramolecular entities.[11–15]
With the advent of mechanically interlocked molecules
(MIMs), ring-in-ring systems have attracted much attention
in the past two decades.[11–15] Different from threaded ring-
in-ring molecules, e.g., catenanes,[16–19] non-intertwined ring-
in-ring motifs are essential precursors for assembling intrigu-
ing supramolecular structures, such as Russian doll-like
assemblies,[20–26] Borromean rings,[12,14, 27, 28] and neotype
rotaxanes.[29,30] Interestingly, a recent report revealed ring-
in-ring(s) complexes, or pseudo-rotaxanes consisting of an
extended tetracationic cyclophane and cucurbit[8]uril show-
ing tunable multicolor photoluminescence via host–guest
complexation.[31] It would be appealing to utilize non-
intertwined ring-in-ring assemblies as a versatile tool for
understanding higher order superstructures by virtue of their
three-dimensional (3D) nature and unique topology. More-
over, the construction of a ring-in-ring system relies mostly
on the use of 3D hosts such as cyclodextrin,[32–34]
calixarene,[21] cucurbituril,[20,23, 31, 35–37] carbon nanohoops,[15,38]
capsules[39] and cages.[13,40–45] The use of two-dimensional
(2D) shape-persistent macrocycles[46–52]—rings with a non-
collapsible molecular backbone—for building ring-in-ring
systems, in which one ring threads through more than two
rings[53] to form a non-intertwined ring-in-rings motif, may
shed new light on this area.
[*] Z. Wang,+S. Huang, Dr. X. Li, W. Feng, Prof. Dr. C. Yang,
Prof. L. Yuan
College of Chemistry, Key Laboratory of Radiation Physics and
Technology of Ministry of Education, Sichuan University
Chengdu, Sichuan 610064 (China)
(The first email address should be )
E-mail: lhyuan@scu.edu.cn
lhyuan@scu.edu.cn
yangchengyc@scu.edu.cn
Dr. L. Mei,+Prof. Dr. W.-Q. Shi
Laboratory of Nuclear Energy Chemistry
Institute of High Energy Physics, Chinese Academy of Sciences
Beijing 100049 (China)
Dr. C. Guo, Prof. X. Li
College of Chemistry and Environmental Engineering
Shenzhen University
Shenzhen, Guangdong 518071 (China)
E-mail: xiaopengli@szu.edu.cn
Prof. X. Li
University General Hospital, Shenzhen University Clinical Medical
Academy, Shenzhen University
Shenzhen, Guangdong 518055 (China)
[+] These authors contributed equally to this work.
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How to cite: Angew. Chem. Int. Ed. 2023, 62, e202216690
International Edition: doi.org/10.1002/anie.202216690
German Edition: doi.org/10.1002/ange.202216690
Angew. Chem. Int. Ed. 2023,62, e202216690 (1 of 11) © 2023 Wiley-VCH GmbH
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