Superstructures with cyclodextrins: Chemistry and applications IV

• Gerhard Wenz

Beilstein J. Org. Chem. 2017, 13, 2157–2159, doi:10.3762/bjoc.13.215

• , belong to this category and have been known since the pioneering work of Friedrich Cramer in 1951 [4][5]. Superstructures can also be held together by repulsive forces, so-called mechanical bonds [6], as exemplified in catenanes, rotaxanes, and knots [7]. Because of their restricted mobility, rotaxanes

• insulin and lysozyme were also conjugated to the guest adamantane. The complexation of these conjugates by pegylated β-CD gives rise to superstructures which provide slow release and maintain full biological activity [21]. Significant progress was also achieved in the field of CD rotaxanes. A [3]-rotaxane

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• these studies led to the preparation of rotaxanes and catenanes, and to the elaboration of the principles of molecular machines, for which J. Fraser Stoddart [4][5][6], Jean-Pierre Sauvage [7][8] and Bernard L. Feringa [9][10] received the Nobel Prize in chemistry in 2016. In addition to Stoddart, the

Interactions between shape-persistent macromolecules as probed by AFM

• Johanna Blass,
• Jessica Brunke,
• Franziska Emmerich,
• Cédric Przybylski,
• Vasil M. Garamus,
• Artem Feoktystov,
• Roland Bennewitz,
• Gerhard Wenz and
• Marcel Albrecht

Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95

• ; shape persistent polymers; Introduction Shape-persistence is an important key feature in self-organisation strategies of supramolecular building blocks resulting in high structural perfection of the obtained molecular assemblies [1], such as shape persistent macrocycles, cage compounds or rotaxanes [2

Creating molecular macrocycles for anion recognition

• Amar H. Flood

Beilstein J. Org. Chem. 2016, 12, 611–627, doi:10.3762/bjoc.12.60

• can be programmed to move and change shape (rotaxanes and catenanes) had hooked my attention. Quite apart from his gift for creating new molecules that are also functional, the number of people who shared co-authorship with him intrigued me. Joining Professor Stoddart’s laboratory in 2002 as a

• cyanostar macrocycles is still being explored. The large binding pockets and the C5 symmetry provide a basis for a lot of new chemistry. This includes use of phosphodiesters as templates for the synthesis of [3]rotaxanes [7] (Figure 13). The other aspect of these macrocycles arising from their π surface is

Art, auto-mechanics, and supramolecular chemistry. A merging of hobbies and career

• Eric V. Anslyn

Beilstein J. Org. Chem. 2016, 12, 362–376, doi:10.3762/bjoc.12.40

• . Keywords: art; assembly; complexity; function; mechanical; supramolecular; Review Introduction The field of supramolecular chemistry abounds with beautiful and aesthetically pleasing molecules. From Stoddart’s rotaxanes [1][2], Sauvage’s knots [3][4], Rebek’s capsules [5], Fujita’s 3-D MOFs [6][7], to

Supramolecular structures based on regioisomers of cinnamyl-α-cyclodextrins – new media for capillary separation techniques

• Gabor Benkovics,
• Ondrej Hodek,
• Martina Havlikova,
• Zuzana Bosakova,
• Pavel Coufal,
• Milo Malanga,
• Eva Fenyvesi,
• Andras Darcsi,
• Szabolcs Beni and
• Jindrich Jindrich

Beilstein J. Org. Chem. 2016, 12, 97–109, doi:10.3762/bjoc.12.11

• will result in changed sieving effects, different selector–analyte interactions and in modulated separation selectivity. CDs have been used as the host component for the construction of various interesting supramolecular structures such as pseudorotaxanes, rotaxanes, supramolecular dimers, oligomers

Supramolecular polymer assembly in aqueous solution arising from cyclodextrin host–guest complexation

• Jie Wang,
• Zhiqiang Qiu,
• Yiming Wang,
• Li Li,
• Xuhong Guo,
• Duc-Truc Pham,
• Stephen F. Lincoln and
• Robert K. Prud’homme

Beilstein J. Org. Chem. 2016, 12, 50–72, doi:10.3762/bjoc.12.7

• blocks in supramolecular structures and functional materials. These are exemplified by catenanes [20][21], rotaxanes [21][22][23][24][25], polyrotaxanes [24][25][26][27][28][29], polymers and polymer networks [12][22][26][30][31][32][33][34]. The focus of this review is on recent developments in the

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• size of the γCD, which might favor both unthreading of the cores, or even accommodation of more than one core unit within the macrocycles cavities. Poor suppression of interchain interactions by γCD had already been observed in the case of diphenylenevinylene rotaxanes, and it is therefore not

Smart molecules for imaging, sensing and health (SMITH)

• Bradley D. Smith

Beilstein J. Org. Chem. 2015, 11, 2540–2548, doi:10.3762/bjoc.11.274

• imaging, ion-pair receptors, rotaxane synthesis, squaraine rotaxanes, and synthtavidin technology. The article concludes with a short perspective of likely future directions in biomedical supramolecular chemistry. Keywords: fluorescence; ion-pair receptors; membrane transport; molecular imaging; rotaxane

• was vital for efficient rotaxane formation. The interlocked molecule retained its salt binding ability and association of the ions modulated the rotaxane structural dynamics [33][34]. Squaraine rotaxanes The interests in molecular imaging and rotaxane structures merged in 2005 with the discovery and

• development of squaraine rotaxanes as a novel family of deep-red fluorescent dyes with extremely high brightness and stability [35][36]. A key finding was the importance of the interlocked rotaxane structure for protecting the encapsulated squaraine from chemical attack by water. Squaraine rotaxanes can be

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

• molecule to give rise to foldamer-derived dynamic rotaxanes [54]. Aromatic hydrazide foldamers: Aromatic hydrazides have a high propensity towards co-planarity [55][56]. Nowick introduced this unit into peptide backbones to increase the stability of artificial β-sheets [55]. Junli hoped to extend the

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

• demonstrate the extensive use of RCM in the synthesis of different metallophanes involving ferrocenophane (e.g., 206) [160] and other metallophanes [161][162][163][164]. The synthesis of mechanically interlocked molecules such as catenanes and rotaxanes which are used to assemble molecular machines, sensors

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• complex alkylating agents can be successfully used in place of methyl iodide. For example, functionalised ethylene glycol oligomers have been used in the preparation of rotaxanes and pseudorotaxanes [28][41][42][45]. Although CsOH·H2O is most commonly used, other bases are also known to remove the

• building blocks in our work on rotaxanes and psuedorotaxanes [45][50]. When the preparation of the same product using each of the two bases is compared, it can be seen that the use of DBU rather than CsOH·H2O usually results in at least a modest increase in yield. We have prepared 4i several times with

• thioether-functionalised MPTTFs to be prepared, including the addition of large ethylene glycol-based substituents utilised in the preparation of rotaxanes and pseudorotaxanes. N-Arylation of MPTTFs is an area of increasing interest and can be achieved using a copper-mediated reaction. We have applied this

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• the β2-adrenergic receptor [24] and rhodopsin [25]. On the field of supramolecular model systems DFS revealed the mechanical stability of coordination bonds [26][27][28], host–guest systems [29][30][31][32], and rotaxanes [33]. In 2008 Guzman et al. analyzed hydrogen bonds of 4H, 6H and 8H chains in

First principle investigation of the linker length effects on the thermodynamics of divalent pseudorotaxanes

• Andreas J. Achazi,
• Doreen Mollenhauer and
• Beate Paulus

Beilstein J. Org. Chem. 2015, 11, 687–692, doi:10.3762/bjoc.11.78

• multivalency [1] and is mainly observed in biochemical systems [2][3][4][5][6][7][8][9]. But the concept of multivalency can be transferred to supramolecular assemblies with suitable building blocks [10][11][12] including (pseudo)rotaxanes [13][14][15] as well. One common building block for pseudorotaxanes is

Superstructures with cyclodextrins: Chemistry and applications II

• Gerhard Wenz

Beilstein J. Org. Chem. 2015, 11, 271–272, doi:10.3762/bjoc.11.30

• soluble in water and able to solubilize hydrophobic active ingredients, they are broadly used in biomedical applications [4]. CDs are also well known to complex suitable monomeric and polymeric guest molecules, leading to supramolecular structures and topological compounds, such as rotaxanes and

Synthesis of an organic-soluble π-conjugated [3]rotaxane via rotation of glucopyranose units in permethylated β-cyclodextrin

• Jun Terao,
• Yohei Konoshima,
• Akitoshi Matono,
• Hiroshi Masai,
• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2014, 10, 2800–2808, doi:10.3762/bjoc.10.297

• cyclodextrin by alteration of the relative orientation of the D-glucopyranoside rings via a flipping (tumbling) mechanism as shown in Figure 2 [19][20][21][22]. From the results of our study on the synthesis of organic-soluble π-conjugated rotaxanes, we report herein the synthesis of insulated oligo(para

• [3]rotaxanes 21 and 22 were also formed quantitatively in an aqueous 50% methanol solution via double self-inclusion through flipping of 17 and 20, respectively (Scheme 5). The formation of these inclusion complexes were also confirmed by 1H NMR spectroscopy in different solvents (Figure 4 and Figure

•  5, Supporting Information File 1, Figure S2). These linked [3]rotaxanes can be key monomers for synthesizing organic soluble IMWs bearing polythiophene or poly(para-phenylene) as backbone units. We next fixed the pseudo rotaxane structure by complexation instead of cross-coupling reaction (Scheme 6

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• used to synthesize copolymers with smaller electrochemical and optical band gaps, so that materials with improved electronic and optical properties can be obtained [17]. The construction of mechanically interlocked molecules such as rotaxanes and polyrotaxanes with native cyclodextrins (CDs) as

Substitution effect and effect of axle’s flexibility at (pseudo-)rotaxanes

• Friedrich Malberg,
• Jan Gerit Brandenburg,
• Werner Reckien,
• Oldamur Hollóczki,
• Stefan Grimme and
• Barbara Kirchner

Beilstein J. Org. Chem. 2014, 10, 1299–1307, doi:10.3762/bjoc.10.131

• substitution with different functional groups and of molecular flexibility by changing within the axle from a single C–C bond to a double C=C bond. Therefore, we present static quantum chemical calculations at the dispersion-corrected density functional level (DFT-D3) for several Leigh-type rotaxanes. The

• . The hydrogen bond geometry between the isophtalic unit and the carbonyl oxygen atoms of the axle exhibited distances in the range of 2.1 to 2.4 Å for six contact points, which shows that not solely but to a large amount the circumstances in the investigated rotaxanes are governed by hydrogen bonding

• binding is weakened by approximately 10 kcal/mol, and hydrogen bonds are slightly shortened (by up to 0.2 Å). Keywords: dispersion interaction; hydrogen bond; supramolecular chemistry; template; theoretical chemistry; Introduction Rotaxanes are prototypes for molecular machines and molecular switches [1

Synthesis and characterization of low-molecular-weight π-conjugated polymers covered by persilylated β-cyclodextrin

• Aurica Farcas,
• Ana-Maria Resmerita,
• Andreea Stefanache,
• Mihaela Balan and
• Valeria Harabagiu

Beilstein J. Org. Chem. 2012, 8, 1505–1514, doi:10.3762/bjoc.8.170

• materials for use in molecular devices, the construction of mechanically interlocked molecules, such as rotaxanes and polyrotaxanes, has attracted considerable attention [19][20][21][22][23]. A rotaxane assembly comprises a macrocyclic component (host) encircling an axle (guest) through noncovalent

• several known host molecules, e.g., crown ethers [32], cyclodextrins (CDs) have been employed for the synthesis of polyrotaxanes with π-conjugated polymers. As a result, many CD-based rotaxanes and polyrotaxanes have been reported until now [5][11][12][19][20][21][22][23][24][25][26][27][28][29][30][31

Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

• Stefanie Potratz,
• Amaresh Mishra and
• Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

• popular and reached high significance in materials synthesis, because high yields and easy to purify products are typically obtained [13][14]. The click chemistry approach was successfully employed to synthesize various oligomers [15][16][17], catenanes and rotaxanes [18], dendrimers [11][19][20], and

Synthesis of multivalent host and guest molecules for the construction of multithreaded diamide pseudorotaxanes

• Nora L. Löw,
• Egor V. Dzyuba,
• Boris Brusilowskij,
• Lena Kaufmann,
• Elisa Franzmann,
• Wolfgang Maison,
• Emily Brandt,
• Daniel Aicher,
• Arno Wiehe and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2012, 8, 234–245, doi:10.3762/bjoc.8.24

• this case to acids and bases, which induce motion of the wheel and axle components relative to each other. Tetralactam macrocycles (TLMs) [65][66] have widely been used in the synthesis of amide catenanes and rotaxanes [85][86][87][88][89][90][91][92] and represent excellent hosts for dicarbonyl

• multivalent host and guest molecules becomes available with this synthetic strategy. In the future, the pseudorotaxanes designed here should be easily converted into rotaxanes after cleavage of the Boc protective group at the axle ends and attachment of stopper groups to the terminal amines. Results and

• complexation-induced signal shifts are even stronger than similar shifts observed for other rotaxanes with a diamide moiety [101]. The fact that proton “3” also shifts significantly indicates that binding may also involve the carbonyl group of the Boc protective group. A reversible shuttling between both the

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• substance classes that have been mostly used in organic ammonium ion recognition: crown ethers, calixarenes [54], cyclodextrins [55][56][57], cucurbiturils, porphyrins, phosphonate based receptors, tripodal receptors, tweezer ligands, clefts, cyclopeptides and metal complexes. We have not included rotaxanes