Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• [12], and drug delivery [13]. In spite of the important advancements in this field, the synthesis and characterization of these fascinating, complex molecules remains an important challenge and often requires intricate synthetic approaches. After the first templated synthesis of a [2]catenane

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• chemosensing or in asymmetric catalysis. The selection of suitable stereogenic elements is of great importance [26][27][28]. The most straightforward way to create a chiral rotaxane or catenane is the introduction of classical chiral elements, such molecular parts with axial chirality, point chirality, or

• ][36][37][38], anion templates [39][40], ammonium crown ether templates [41], and templates based on π–π interactions [42]. In 2004, Sauvage and co-workers have used a Cu(I)-based passive metal template approach to synthesize a [2]catenane containing an optically pure BINOL unit in each macrocycle [43

• the formation of the desired chiral homocircuit [2]catenane (S,S)-5 in 21% yield. By treating (S,S)-5 with a large excess of aqueous KCN, demetalation occurred to give the corresponding [2]catenane (S,S)-6. Interestingly, the Cu-containing catenane (S,S)-5 shows a strong CD signal at wavelengths

Five-component, one-pot synthesis of an electroactive rotaxane comprising a bisferrocene macrocycle

• Natalie Lagesse,
• Luca Pisciottani,
• Maxime Douarre,
• Pascale Godard,
• Brice Kauffmann,
• Vicente Martí-Centelles and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2020, 16, 1564–1571, doi:10.3762/bjoc.16.128

• to perform several functions as artificial molecular switches [1]. The template-directed synthesis of such sophisticated catenane and rotaxane molecular architectures allowed the expansion of chemical diversity and properties. Among these architectures, electroactive rotaxanes have been described to

• material. In contrast, in the absence of the template both reactive groups were not positioned in a geometry favouring macrocycle formation, which may prove conducive to oligomerization or catenane formation (Figure 3a). The 1H NMR spectrum of the rotaxane 1a in CDCl3 (Figure 4) showed a characteristic

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• receptors for molecular recognition of anionic species, pH sensors, mechanically interlocked molecules, molecular machines, and molecular reactors. Keywords: anion recognition; catenane; chalcogen bonding; click reaction; molecular reactor; hydrogen bonding; pH sensor; rotaxane; supramolecular; 1,2,3

• analogous experiment was done with benzoate, due to the precipitation of an insoluble ferrocenium complex [40]. 2.4. Mechanically interlocked catenanes containing 1,2,3-triazolium macrocycles Mechanically interlocked molecules like rotaxane and catenane have attracted much attention in the field of

• as components of functional molecular devices, such as switches [42][43], unidirectional motors [44], electronic displays [45] as well as in anion recognition [46]. Interestingly, Beer et al. have attempted the synthesis of tetratriazolium hetero-catenane, but the purification and isolation was felt

Synthesis of a [6]rotaxane with singly threaded γ-cyclodextrins as a single stereoisomer

• Jason Yin Hei Man and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2019, 15, 1829–1837, doi:10.3762/bjoc.15.177

• -conjugated polymers [29][30][31]. On the other hand, γ-CD is relatively less employed in the synthesis of mechanically interlocked molecules despite of its ability to form interesting 1:2 inclusion complexes, and there are only few examples of rotaxane and catenane featuring γ-CD as an interlocked macrocycle

• complex, multicomponent rotaxane, catenane and other mechanically interlocked architectures and the potential applications thereof. LC–MS analysis of the reaction mixture of the [n]rotaxane synthesis in the presence of (a) 0.5; (b) 5; (c) 10; (d) 20; and (e) 50 equiv of γ-CD. Partial 1H NMR spectra (500

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• supramolecular assemblies like molecular rotors (pseudorotaxane, rotaxane, catenane), molecular switches, molecular shuttles, etc. [32][33][34][35][36][37][38][39][40][41][42][43]. Furthermore, macrocycles have been applied in the area of ion–ion pair recognition and heterometallic complex formation [44][45][46

Molecular recognition using tetralactam macrocycles with parallel aromatic sidewalls

• Dong-Hao Li and
• Bradley D. Smith

Beilstein J. Org. Chem. 2019, 15, 1086–1095, doi:10.3762/bjoc.15.105

• following sections, we divide the guest structures into two large categories; those that associate with a tetralactam host in a reversible solution-state equilibrium and those that are permanently trapped inside a tetralactam macrocycle as an interlocked rotaxane or catenane. It is important to emphasize

• ] macrocycle and a larger amount of the corresponding [2]catenane. Subsequent work found that conducting the reaction in the presence of a dumbbell-shaped template was a general way to make a wide range of [2]rotaxanes [28]. Listed in Scheme 2 are the yields of [2]rotaxane produced using various biscarbonyl

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• clutch, a common technical device used in motor vehicles. Furthermore, rotaxane 23 can be used as novel supramolecular gearing system for the transmission of rotational motion at the molecular level. 5. Rotacatenanes In 2011, the group of Stoddart described the fusion of a rotaxane and a catenane, a so

• arrangement. Starting from the pre-assembled catenane, the axle molecule is threaded through the wheel and end-capped by a copper-catalyzed click reaction. A variety of different spectroscopic and electrochemical methods was applied to reveal the switching behavior of 24 and its stable co-conformations in

• rotaxanes in which the wheel is only held on the axle component by steric hindrance of stopper groups, a catenane is a truly topologically interlocked species bearing a mechanical bond. However, the construction, chemical behavior, and operation of structurally related rotaxanes and catenanes are often very

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

• Carmine Gaeta,
• Carmen Talotta and
• Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

• their ability to adopt novel forms of isomerism. More in detail, (pseudo)rotaxane or catenane architectures can show novel stereoisomeric forms as a result of the "social" [14] relationship between their components. Recently, Goldup’s group assembled a mechanically planar chiral rotaxane [15][16] (I and

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• ][5][6][7]. During the past years, a large number of different MIMs has been constructed, such as handcuff catenane [8], molecular elevators [9][10], molecular muscles [11][12], trefoil necklace [13][14][15], molecular walkers [16][17][18] and molecular pumps [19][20]. Combining the stimuli-responsive

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• alkyl chain rings, and formed a self-inclusion structure in aqueous media, which was assigned as a pseudo[1]catenane structure. The hydrophobic chain ring was hidden inside the pillar[5]arene cavity in the pseudo[1]catenane structure, thus the bicyclic compound was soluble in water at 20 °C with a

• clouding point at 24 °C. The pseudo[1]catenane was converted to the de-threaded structure upon addition of the neutral guest 1,4-dicyanobutane, which displaced the alkyl chain ring from the inside to the outside of the cavity. The hydrophobic alkyl chain ring was now exposed to the aqueous media, causing

• aggregation of the hydrophobic alkyl chain rings, which induced insolubilization of the bicyclic compound in aqueous media at 20 °C and a decrease in its clouding point. Keywords: amphiphilic molecules; host–guest complexes; lower critical solution temperature; pillar[n]arenes; pseudo[1]catenane

A pyridinium/anilinium [2]catenane that operates as an acid–base driven optical switch

• Sarah J. Vella and
• Stephen J. Loeb

Beilstein J. Org. Chem. 2018, 14, 1908–1916, doi:10.3762/bjoc.14.165

• Sarah J. Vella Stephen J. Loeb Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada 10.3762/bjoc.14.165 Abstract A two-station [2]catenane containing a large macrocycle with two different recognition sites, one bis(pyridinium)ethane and one

• bis(pyridinium)ethane site, while addition of acid forms a charged benzylanilinium site. The DB24C8 then shuttles between the two charged recognition sites with occupancy favoring the bis(pyridinium)ethane site by a ratio of 4:1. The unprotonated [2]catenane has a deep yellow/orange color when the

• DB24C8 ring resides solely at the bis(pyridinium)ethane site and changes to colorless when the crown ether is shuttling (i.e., circumrotating) back and forth between the two recognition sites thus optically signalling the onset of the shuttling dynamics. Keywords: catenane; mechanically interlocked

Efficient catenane synthesis by cucurbit[6]uril-mediated azide–alkyne cycloaddition

• Antony Wing Hung Ng,
• Chi-Chung Yee,
• Kai Wang and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2018, 14, 1846–1853, doi:10.3762/bjoc.14.158

• other recognition units render them promising building blocks for the construction of other high-order interlocked structures. Keywords: azide–alkyne cycloaddition; catenane; click chemistry; cucurbit[6]uril; mechanical bond; Introduction Catenanes are topologically non-trivial molecules possessing

• ring-closing reactions to form the interlocked macrocycles have been developed, but the majority of the reported catenanes is limited to the Hopf link (i.e., the simplest [2]catenane with two crossings) [9]. Synthesis of other high-order catenanes with more interlocked macrocycles and/or more crossing

• points remain challenging and more general synthetic strategies to catenanes are yet to be realized [10][11][12]. A major challenge in [n]catenane synthesis is the precise spatiotemporal control of the covalent formation of the macrocycles and their mechanical interlocking. Otherwise, various topological

Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

• Anne L. Schöffler,
• Ata Makarem,
• Frank Rominger and
• Bernd F. Straub

Beilstein J. Org. Chem. 2016, 12, 1566–1572, doi:10.3762/bjoc.12.151

• bioactive surfaces [8][14], imaging of biochemical processes [15], localization of bioactive compounds inside living cells [16], syntheses of small-molecule screening libraries [17], catenane and rotaxane syntheses [18], in reactions under continuous flow processing [19], polymer and surface science [20][21

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• , supramolecular catenane [42][43]. Carol Lamberson synthesized macrocyclic diacridine 23 with spermine and diamide linker chains long enough to allow binding according to the nearest neighbor exclusion principle (e.g., a complex such as 22). All the data collected showed that this “topologically constrained

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• ]catenane 6c with the tetracationic cyclophane holding one of the peripheral benzene rings [14]. The TTF unit in 6a and 6b adopted a stable cis or trans configuration, although typically the two configurations easily isomerize into each other in solution. Macrocycle 3 is a brown solid due to the existence

• of the TTF unit. Catenanes 6a and 6b are blue as a result of the charge-transfer complex between the TTF and bipyridinium units, whereas catenane 6c is orange, which is attributed to the charge-transfer complex between the dioxybenzene and bipyridinium units. Impressively, the three catenanes could

• –C60 stacking [35], while compound 17 strongly complexed 18 in the chloroform–acetonitrile binary medium [36] (Scheme 8). Because 18 could further form a threaded complex with 24-crown-8 19 driven by multiple O···H–N hydrogen bonds, the three components self-assembled into a unique dynamic [2]catenane

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• and nanomaterials is a challenging task. Huang and co-workers [165] have reported a taco complex template method to synthesize a cryptand/paraquat [2]rotaxane and [2]catenane (e.g., 207) by using RCM as a key step. Structural features and interesting bioactivity of the hirsutellones have grabbed the

Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests

• Yoann Cotelle,
• Marie Hardouin-Lerouge,
• Stéphanie Legoupy,
• Olivier Alévêque,
• Eric Levillain and
• Piétrick Hudhomme

Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115

• ]catenane [53], cucubit[8]uril [54] or self-assembled cages [55] which facilitate the formation of TTF dimers. Studying the glycoluril-based molecular clip 15 presenting also TTF sidewalls [56][57], Chiu et al. have observed the mixed-valence and radical cation dimer states at high concentration (10−3 M

Molecular assembly of amino acid interlinked, topologically symmetric, π-complementary donor–acceptor–donor triads

• M. B. Avinash,
• K. V. Sandeepa and
• T. Govindaraju

Beilstein J. Org. Chem. 2013, 9, 1565–1571, doi:10.3762/bjoc.9.178

• [18], catenane [19], rotaxane [20], self-healable supramolecular polymer [21], aromatic stacking within a coordination cage [22], superamphiphile [23] and thermochromic [24] materials. Notably, Wilson et al. have reported preferential π-stacking of pyrene and NDI amongst a pool of π-electron D-A