Effect of a photoswitchable rotaxane on membrane permeabilization across lipid compositions

• Udyogi N. K. Conthagamage,
• Lilia Lopez,
• Zuliah A. Abdulsalam and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2498–2512, doi:10.3762/bjoc.21.192

• , including rotaxane 1-E, rotaxane 1-Z, rotaxane 2, and axle 3. Rotaxane 2 and axle 3 were used as controls to understand the effect of subcomponents of rotaxane 1 on membrane permeabilization and dye release (Table 1, Figure 4a, and Supporting Information File 1, S2.2). In LUVs composed solely of EYPC, both

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• reported the first [3]rotaxane with three azobenzene units in the axle and two α-cyclodextrins as the macrocycle. The rotaxane was obtained as a single stereoisomer, where the two narrow rings of the cyclodextrin point to each other. Although no photoswitching studies were conducted, 1H NMR results showed

• . Although no shuttling or energy transfer process was observed, both rotaxanes presented good photoisomerization behavior. Remarkably, the use of cucurbit[6]uril macrocycles enhanced the photoisomerization. Later, Liu and co-workers designed a symmetric [3]rotaxane where the pH-responsive shuttling motion

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• end-capping reaction. As a pseudorotaxane structure could be decomposed during measurements (e.g., a solution-based NMR measurement), a more stable rotaxane structure is preferred for the analysis. Therefore, we developed a facile [3]rotaxane synthesis method based on a urea end-capping method to

• produce simple structured rotaxane species (Scheme 3) [46][47][48]. In this method, dodecanediamine and α-CD are mixed in water to form a pseudo[3]rotaxane (1), and the subsequent one-pot end-capping reaction driven by the amino group on the axle ends and substituted phenyl isocyanate produced [3]rotaxane

• other synthetic methods: (1) the reaction can proceed on a 100 g scale in a 1 L flask and a 500 mL solution of water, sufficiently indicating the possibility of large-scale material applications; (2) the product contains only head-to-head structured [3]rotaxane, as confirmed by the X-ray crystal

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

• to slightly better stereodiscrimation of the guest molecules (see Figure 17). Subsequently, Beer and co-workers reported the first example of a chiral halogen-bonding [3]rotaxane for the recognition and sensing of dicarboxylate anions [64]. The [3]rotaxane (S)-68 was prepared in a two-fold clipping

• macrocycle (S)-61-Me22+. Only the first association constant (K11) is given. aIn acetone-d6/D2O 98:2. bIn acetone-d6/D2O 99:1. Synthesis of Beer´s [3]rotaxane (S)-68. Association constants of different anions (used as the Bu4N+-salts) to the [2]rotaxane (S)-68 and axle (S)-65. Only the first association

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

• dialkylammonium axles. The formation of pseudo[2]rotaxane, pseudo[3]rotaxane, and pseudo[4]rotaxane by threading one, two, and three, respectively, calix-wheels of 6 has been studied by 1D and 2D NMR, DOSY, and ESI-FT-ICR MS/MS experiments. The use of a directional alkylbenzylammonium axle led to the

• ]arene derivative 1 with bisammonium axles (e.g., 22+). In addition, we have also shown that the bis-calix[6]arene 1 was able to form pseudo[3]rotaxane architectures (e.g., 52+ in Figure 2) by double-threading with dialkylammonium axles [28]. With the aim to increase the complexity of our system we have

• at 5.13 ppm and 4.96 ppm, two new broad singlets in a 1:2 ratio emerged at 5.08 and 5.06 ppm attributable to the benzylic methylene groups of the central benzene core of 6 in the double-threaded (7+)26 pseudo[3]rotaxane (Scheme 2). These data suggested that in a 1:2 mixture of 6 and 7+·TFPB− in CDCl3

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

• [32][33][34][35][36]. By adopting a stepwise stoppering approach, Anderson and co-workers have synthesized a [3]rotaxane consisting of two different axles, derived from a stilbene and a cyanine, threaded through one γ-CD [33]. Inouye has also reported a [3]rotaxane with two pyrene-derived axles

• by LC–MS. Contrary to most reports on the inclusion of simple aromatic or poly(ethylene glycol) in γ-CD where a 2:1 binding stoichiometry was observed, LC–MS analysis of the reaction mixture containing a 2:1 molar ratio of 1/γ-CD stoppered by 2 showed only the [3]rotaxane 3R (93%, m/z = 798.0, 4

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

• written data could be read out even after waiting for 12 h. Besides data storage, a substantial challenge of AMMs is the transfer of molecular motion into a useful macroscopic output. An example of rotaxanes on a solid support which could achieve this is shown in Figure 19 [96]. The [3]rotaxane 21

• switching state of a system as a whole need to be considered for the design and operation of an AMM. In addition to the variety of TTF-based rotaxane shuttles, we recently reported a [3]rotaxane in which the pirouetting motion of wheels can be controlled by electrochemical switching [98]. Figure 21 shows

• the [3]rotaxane 23 which bears two cofacially oriented TTF crown ethers on a divalent ammonium axle. The distance between the wheels is convenient for TTF-dimer interactions. In the non-switched neutral state of both TTFs, the wheels adopt a syn co-conformation caused by weak non-covalent interactions

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

• -flat wheels, such as calixarenes or cyclodextrins, are threaded along an axle to give a pseudo[3]rotaxane architecture V–VII (Figure 2), where three sequential stereoisomers can arise. We showed that this stereoisomerism can be effectively controlled when two calix[6]arene wheels are threaded along a

• bis(benzylalkylammonium) axle [19], where the stereoselective formation of the pseudo[3]rotaxane with endo-alkyl orientation VIII was observed [19]. Calixarene macrocycles [22] have found numerous applications in several areas of supramolecular chemistry, such as (bio)molecular recognition [23] and

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

• decided to first assemble a pseudo[3]rotaxane CB[6] complex with either the azide or alkyne building block, before introducing the other building block to the reaction mixture. By heating a solution of DN-N3 in the presence of two equivalents of CB[6] in 0.2 M aq HCl for 2 hours, a clear solution was

• mixture contained the [3]catenane Cat-1 as the major product with >85% yield (Scheme 2). Using DN-CC to first form the pseudo[3]rotaxane CB[6] complex did not affect the efficiency of CBAAC and Cat-1 was obtained in a similar yield. These results show that the initial formation of the pseudorotaxane

Superstructures with cyclodextrins: Chemistry and applications IV

• Gerhard Wenz

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

• 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

Creating molecular macrocycles for anion recognition

• Amar H. Flood

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

• plot of anion affinities (40:60 methanol/dichloromethane). (a) Representation and (b) crystal structure of cyanostar-based [3]rotaxane. Crystal structures of cyanostar sandwich around (a) perchlorate and (b) diglyme (molecules shown with stick models and representative electron-density contours). Part

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

• -phenylene) and oligothiophene with a pseudo-linked [3]rotaxane structure by full rotation of glucopyranose units via a flipping (tumbling) mechanism in the π-conjugated guest having two permethylated β-cyclodextrin units at both ends. We also succeeded in the synthesis of an organic-soluble fixed [3

• ]rotaxane by a cross-coupling or complexation reaction of thus formed pseudo linked [3]rotaxane. Oligo(para-phenylene), oligothiophene, and porphyrin derivatives were used as π-conjugated guests with stopper groups. Keywords: cross-coupling reaction; insulated π-conjugated molecule; oligothiophene

• ; permethylated cyclodextrin; [3]rotaxane; Introduction Insulated molecular wires (IMWs) [1][2], which feature π-conjugated polymer chains covered by protective sheaths, have attracted considerable attention as next-generation mono-molecular electronic devices because of their potential conductivity and

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

• low-barrier molecular rotary motors with rotaxane architecture [24]. The co-conformational selectivity of two dibenzo-24-crown-8 macrocycles to ammonia binding sites in a [3]rotaxane [25], and the hydrogen bonding strength in polymeric urethane rotaxanes in a mean-field model [26] were investigated by

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