Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• motifs in rotaxane-based polymers has also provided interesting properties which can be employed in some specific implementations. α-Cyclodextin-based polyrotaxanes 2 having trithiocarbonate stopper groups with an adjacent phenyl group were employed for the construction of visible light-degradable

Multiple threading of a triple-calix[6]arene host

• Veronica Iuliano,
• Roberta Ciao,
• Emanuele Vignola,
• Carmen Talotta,
• Patrizia Iannece,
• Margherita De Rosa,
• Annunziata Soriente,
• Carmine Gaeta and
• Placido Neri

Beilstein J. Org. Chem. 2019, 15, 2092–2104, doi:10.3762/bjoc.15.207

• ]. Among the self-assembly processes, those that lead to the formation of interlocked and/or interpenetrated supramolecular structures have inspired many scientists [5][6][7][8]. The synthesis of interlocked molecules such as rotaxanes, catenanes, and high-order architectures (e.g., polyrotaxanes, suitanes

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

• , polyrotaxanes and polycatenanes. Experimental Materials. All solvents and reagents were used as supplied. Compounds 1 and 4 were synthesized according to previous reported procedures [5][17]. Measurements. The 1H NMR spectra were recorded at 500 MHz and 13C NMR spectra were recorded at 125 MHz with a JEOL

Crystal structure of the inclusion complex of cholesterol in β-cyclodextrin and molecular dynamics studies

• Elias Christoforides,
• Andreas Papaioannou and
• Kostas Bethanis

Beilstein J. Org. Chem. 2018, 14, 838–848, doi:10.3762/bjoc.14.69

• increased safety in NPC animal models [12]. Moreover, superstructures of cyclodextrins like mono-lactose-appended β-CD [13] and biocleavable pluronic/β-CD-based polyrotaxanes [14] as well as PEG-lipid micelles (DSPE-PEG) in combination with HP-β-CD [15] have shown enhanced therapeutic effects and exhibit a

Superstructures with cyclodextrins: Chemistry and applications IV

• Gerhard Wenz

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

• magnetic resonance imaging (MRI) [22]. Well-defined fluorescent polyrotaxanes with alternating, threaded cucurbit[6]uril and CD rings were assembled by Fraser Stoddart’s group via an alkyne–azide click reaction exploiting supramolecular catalysis [23][24]. The concurrent radical copolymerization of 1,3

• -dienes and bulky stoppers in the presence of CDs (so-called rotaxa-polymerization) was further applied for the syntheses of water-soluble polyisoprene polyrotaxanes [25]. Furthermore, ABA-type block-copolyrotaxanes could be synthesized using this polymerization technique controlled by RAFT chain transfer

• agents [26]. The exciting world of CD polyrotaxanes, including self-healing materials [27], was highlighted at a special session “Smart Polymers and Materials from Cyclodextrins: Novel Designs and Functions” at the 253rd ACS National Meeting in San Francisco in spring 2017. This Thematic Series in the

One-pot synthesis of block-copolyrotaxanes through controlled rotaxa-polymerization

• Jessica Hilschmann,
• Gerhard Wenz and
• Gergely Kali

Beilstein J. Org. Chem. 2017, 13, 1310–1315, doi:10.3762/bjoc.13.127

• further effects the CD content and the aqueous solubility of the polyrotaxane. Keywords: block copolymer; cyclodextrin; polyisoprene; polyrotaxane; RAFT polymerization; Introduction Polymer necklaces, i.e., polyrotaxanes and pseudopolyrotaxanes, are supramolecular assemblies comprising polymeric axes

• with macrocycles threaded on them [1][2][3][4]. In the case of polyrotaxanes, the dethreading of the macrocycles is prevented by bulky stopper groups placed along the chain or at the chain ends. The importance of these supramolecules lies in the possibility to modify the properties, or even cross-link

• ]. There are several CD-based polyrotaxanes known with homo- and block-copolymer axes, mostly based on poly(ethylene oxide), poly(propylene oxide) or their copolymers [15][16][17][18][19][20][21], since these polymers can form sufficiently stable complexes with CDs. The application potential of these

Versatile synthesis of end-reactive polyrotaxanes applicable to fabrication of supramolecular biomaterials

• Atsushi Tamura,
• Asato Tonegawa,
• Yoshinori Arisaka and
• Nobuhiko Yui

Beilstein J. Org. Chem. 2016, 12, 2883–2892, doi:10.3762/bjoc.12.287

• polyrotaxanes (PRXs) with reactive functional groups at the terminals of the axle polymers are attractive candidates for the design of supramolecular materials. Herein, we describe a novel and simple synthetic method for end-reactive PRXs using bis(2-amino-3-phenylpropyl) poly(ethylene glycol) (PEG-Ph-NH2) as

• an axle polymer and commercially available 4-substituted benzoic acids as capping reagents. The terminal 2-amino-3-phenylpropyl groups of PEG-Ph-NH2 block the dethreading of the α-CDs after capping with 4-substituted benzoic acids. By this method, two series of azide group-terminated polyrotaxanes

• functional PRXs and can be applied to the fabrication of PRX-based supramolecular biomaterials. Keywords: azide group; biomaterials; click chemistry; cyclodextrin; polyrotaxane; Introduction Polyrotaxanes (PRXs) are a class of interlocked polymers that consist of an inclusion complex of cyclodextrins (CDs

Superstructures with cyclodextrins: chemistry and applications III

• Gerhard Wenz and
• Eric Monflier

Beilstein J. Org. Chem. 2016, 12, 937–938, doi:10.3762/bjoc.12.91

• has been achieved in the synthesis of CD polyrotaxanes. The one-pot and one-step polyrotaxane synthesis of β-CDs was performed in aqueous solution by employing a click reaction [7] as well as by radical copolymerization [8]. Slide-ring gels, synthesized by the group of K. Ito through the crosslinking

• of the hydroxy groups of CD polyrotaxanes, showed peculiar material properties [9] such as extreme stretchability [10]. These mobile networks are potentially useful as self-healing coatings [11]. Finally, recent results have shown that CDs are precious molecular tools that can be used for the design

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

• backbones Since the report of host–guest complexation between α-CD and poly(ethylene glycol) (PEG) by Harada and Kamachi in 1990 [82], a variety of pseudo-polyrotaxanes and polyrotaxanes formed through host–guest complexation between cyclodextrins and linear polymers have been reported [83], some of which

• -polyrotaxanes crystallized to form interchain links within the hydrogel. Similar conclusions were reached from another X-ray powder diffraction study of frozen α-CD/PEG hydrogels formed with PEG of 8, 20 and 600 kDa molecular weights [87]. The accompanying rheological and differential scanning calorimetric

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

• University College London, Gower Street, London WC1E 6BT, UK Laboratoire de Physicochimie des Polymères et des Interfaces (EA 2528), Institut des Matériaux, Université de Cergy-Pontoise, F-95031 Cergy-Pontoise Cedex, France 10.3762/bjoc.11.288 Abstract Two alternating polyfluorene polyrotaxanes (3·TM-βCD

• polyrotaxane compounds exhibit a granular morphology with lower dispersity and smaller roughness exponent of the film surfaces in comparison with those of the neat copolymer 3. Keywords: energy band gaps; fluorescence lifetimes; permethylated cyclodextrins; polyfluorene; polyrotaxanes; Introduction Over the

• unique properties, and novel practical applications. The construction of polyrotaxane architectures has an impact on the polymer-chain behavior and subsequently generates smart functional polymeric materials [28][29][30][31]. Polyrotaxanes with conjugated polymers have attracted considerable attention

Self-assemblies of γ-CDs with pentablock copolymers PMA-PPO-PEO-PPO-PMA and endcapping via atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine

• Jing Lin,
• Tao Kong,
• Lin Ye,
• Ai-ying Zhang and
• Zeng-guo Feng

Beilstein J. Org. Chem. 2015, 11, 2267–2277, doi:10.3762/bjoc.11.247

• phosphorylcholine (MPC), these single-chain-stranded loose-fit PPRs were transformed into conformational identical polyrotaxanes (PRs). The structures of the PPRs and PRs were characterized by means of 1H NMR, GPC, 13C CP/MAS NMR, 2D 1H NOESY NMR, FTIR, WXRD, TGA and DSC analyses. Keywords: ATRP; γ-CD; double

• character and deformable cavity size allow for the self-assembly or inclusion of various polymer chains to generate poly(pseudorotaxanes) (PPRs) or polyrotaxanes (PRs) after endcapping with bulky stoppers. Since Harada et al. first reported the α-CD-based single-chain-stranded PPRs constructed from the

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• by a novel network formed using cyclodextrin-based polyrotaxanes. Covalent bond formation between the cyclic components of polyrotaxanes and the surface of silica nanoparticles (15 nm diameter) resulted in an infinite network structure without direct bonds between the main chain polymer and the

• through the cross-links and lead to several unique properties [11][12][13][14][15][16]. Polyrotaxanes were also applied for surface modification of substrates by attaching the cyclic components to the surface [17]. These results were based on the indirect connection among different polymers or between

• , formation of chemical bonds between the cyclic components of polyrotaxanes to the surface of a nanoparticle may result in a network structure where the nanoparticle acts as a cross-linker. As the first model system, we employed a silica nanoparticle and a CD-based polyrotaxane whose rings were chemically

Superstructures with cyclodextrins: Chemistry and applications II

• Gerhard Wenz

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

• polyrotaxanes [5][6][7]. The solubility and stability of CD complexes are controllable through the derivatization of CDs. Remarkable progress has been achieved over the past 10 years regarding the regioselective derivatization of cyclodextrins. Synthetic procedures for CD key derivatives such as mono-6-O-tosyl

Release of β-galactosidase from poloxamine/α-cyclodextrin hydrogels

• César A. Estévez,
• José Ramón Isasi,
• Eneko Larrañeta and
• Itziar Vélaz

Beilstein J. Org. Chem. 2014, 10, 3127–3135, doi:10.3762/bjoc.10.330

• copolymer. α-CD must surpass the outer PPO blocks to reach the PEO blocks and form stable structures known as (pseudo)polyrotaxanes. PEO chains and oligoethylenes of different molecular weights form inclusion complexes with α-CD. On the other hand, the wider PPO chains yield inclusion complexes with β and γ

Preparation and evaluation of cyclodextrin polypseudorotaxane with PEGylated liposome as a sustained release drug carrier

• Kayoko Hayashida,
• Taishi Higashi,
• Daichi Kono,
• Keiichi Motoyama,
• Koki Wada and
• Hidetoshi Arima

Beilstein J. Org. Chem. 2014, 10, 2756–2764, doi:10.3762/bjoc.10.292

• both ends of the polymer chains in PPRXs with bulky molecules results in the trapping of CDs, which in this case cannot be de-threaded from the assembly, hence giving rise to polyrotaxanes [12][13]. Recently, PPRXs and polyrotaxanes have been utilized as drug carriers for low-molecular weight drugs [14

Synthesis of graft polyrotaxane by simultaneous capping of backbone and grafting from rings of pseudo-polyrotaxane

• Kazuaki Kato,
• Katsunari Inoue,
• Masabumi Kudo and
• Kohzo Ito

Beilstein J. Org. Chem. 2014, 10, 2573–2579, doi:10.3762/bjoc.10.269

• , 277-0882, Japan 10.3762/bjoc.10.269 Abstract Graft polyrotaxanes, with poly(ε-caprolactone) (PCL) graft chains on the ring components were synthesized by the simultaneous ring-opening polymerization of ε-caprolactone from both ends of the backbone polymer, an end-functionalized polyethylene glycol

• backbone ends resulted in a star-shaped end group, which served as a bulky capping group to prevent dethreading. In contrast, PEG with only one hydroxy group at each end did not produce polyrotaxanes, indicating that single PCL chains were too thin to confine α-CDs to the complex. In addition, the grafting

• polymerization proceeded properly only when robust hydrogen bonds formed between α-CDs were dissociated using a basic catalyst. Since the dissociation also induced dethreading, kinetic control of the polymerization and dissociation were crucial for producing graft polyrotaxanes. Consequently, this three-step

Loose-fit polypseudorotaxanes constructed from γ-CDs and PHEMA-PPG-PEG-PPG-PHEMA

• Tao Kong,
• Lin Ye,
• Ai-ying Zhang and
• Zeng-guo Feng

Beilstein J. Org. Chem. 2014, 10, 2461–2469, doi:10.3762/bjoc.10.257

• to not only small guest molecules, but also to linear polymeric guest molecules. They can self-assemble into novel inclusion complexes (ICs), or polypseudorotaxanes (PPRs) and polyrotaxanes (PRs) end-capped by bulky stoppers. For example, α-CDs typically include PEG, but not PPG, β-CDs contain PPG

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

• polyrotaxanes (4a and 4b), which consist of electron-accepting 9,9-dicyanomethylenefluorene 1 as an inclusion complex in persilylated β- or γ-cyclodextrin (TMS-β-CD, TMS-γ-CD) (1a, 1b) and methyltriphenylamine as an electron-donating molecule. They are statistically distributed into the conjugated chains of 9,9

• -dioctylfluorene 3 and compared with those of the corresponding non-rotaxane 4 counterpart. Rotaxane formation results in improvements of the solubility, the thermal stability, and the photophysical properties. Polyrotaxanes 4a and 4b exhibited slightly red-shifted absorption bands with respect to the non-rotaxane

• 4 counterpart. The fluorescence lifetimes of polyrotaxanes follow a mono-exponential decay with a value of τ = 1.14 ns compared with the non-rotaxane, where a bi-exponential decay composed of a main component with a relative short time of τ1 = 0.88 (57.08%) and a minor component with a longer

The β-cyclodextrin/benzene complex and its hydrogen bonds – a theoretical study using molecular dynamics, quantum mechanics and COSMO-RS

• Jutta Erika Helga Köhler and
• Nicole Grczelschak-Mick

Beilstein J. Org. Chem. 2013, 9, 118–134, doi:10.3762/bjoc.9.15

• chains of proteins [6], to size control of the electrostatic self assembly of nanoparticles [7]. Also a pH-controlled release of many cyclodextrins in long stacks on polymers, such as polyrotaxanes, combined with mesoporous silica particles was observed [8]. Complex formation with solvent molecules can

Polysiloxane ionic liquids as good solvents for β-cyclodextrin-polydimethylsiloxane polyrotaxane structures

• Narcisa Marangoci,
• Rodinel Ardeleanu,
• Laura Ursu,
• Constanta Ibanescu,
• Maricel Danu,
• Mariana Pinteala and
• Bogdan C. Simionescu

Beilstein J. Org. Chem. 2012, 8, 1610–1618, doi:10.3762/bjoc.8.184

• interactions. The structure is stable in the 20 to 80 °C domain as proved by the oscillatory and rotational rheological tests. Keywords: cyclodextrins; imidazolium salt; ionic liquid; polyrotaxanes; polysiloxanes; Introduction Ionic liquids (ILs) are environmentally friendly solvents with great potential for

• number of works that showed their use as solvents or as solvents for synthesis and catalysis [4][5][6]. In this context ILs, which have polar and nonpolar regions, could play an important role in the field of supramolecular organization of different supramolecular structures (such as polyrotaxanes or

• macrocycle from slipping out [13][14][15][16][17][18][19][20][21][22]. Unfortunately, the properties and mechanisms of CD-polymer polyrotaxanes have been rarely evaluated due to a lack of good solvents. In general, the CD-polymer polyrotaxanes are soluble only in DMSO and aqueous sodium hydroxide solution

Supramolecular hydrogels formed from poly(viologen) cross-linked with cyclodextrin dimers and their physical properties

• Yoshinori Takashima,
• Yang Yuting,
• Miyuki Otsubo,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1594–1600, doi:10.3762/bjoc.8.182

• employs cyclodextrin (CD) as a host molecule, because CD effectively forms polyrotaxanes with polymers. Herein we report the formation of supramolecular hydrogels with an α-CD dimer (α,α-CD dimer) as a topological linker molecule, and a viologen polymer (VP) as the polymer chain. The supramolecular

• of functional soft materials has attracted much attention due to the numerous practical applications [1][2][3]. Typically, soft materials fall into one of two types of gels: physical gels and chemical gels [4][5][6][7][8][9]. Recently, topological cross-linked polyrotaxanes have been identified as

• tertiary gels, which should create a new paradigm in materials science [10]. Polyrotaxanes form topological gels, because the rotor molecules, which act as cross-linkers, slide on the axial polymer chain. In contrast, chemical gels do not exhibit cross-linker slippage. Previously, there have been some

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

• bulkier silylated groups, affecting the ability of the diborate groups from the DOF molecule to partially penetrate the PS-βCD cavity. Keywords: alternating fluorene-bithiophene copolymer; cyclodextrins; interlocked molecules; macrocycles; persilylated β-cyclodextrin; polyrotaxanes; Introduction Organic

• 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

• polymeric architectures. Moreover, the fabrication of mechanically interlocked molecules, such as polyrotaxanes, has been investigated as a method for the further improvement of thermal and electro-optical properties through the insulating backbones of conjugated polymers [20][21][22][23][24]. The studies