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Search for "[2]rotaxanes" in Full Text gives 11 result(s) in Beilstein Journal of Organic Chemistry.

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  • -complementary rotaxanes offer another option for controlling the structure of CD-based rotaxanes. Although only a few size-complementary rotaxanes have been reported, even for those comprising other ring molecules, some examples are introduced below. In 1998, Stoddart and co-workers reported pseudo[2]rotaxanes
  • the deslipping reaction of [2]rotaxanes exhibiting a deoxynucleotide on the axle-end structure (Figure 8B) [73]. They clarified that the deslipping proceeded faster from the bigger rim side of the CD cavity, as expected. However, the direct utilization of those frameworks in the polymer system is
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Published 19 Nov 2024

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

Graphical Abstract
  • beautiful structures and intriguing properties. We present herein a new synthetic strategy to access [2]rotaxanes, namely active-metal template clipping. We discuss the design of the target [2]rotaxanes, synthesis and characterization of the axle, macrocycle precursors and macrocycles as well as preparation
  • of the final [2]rotaxanes by active template copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) as key step of the synthesis. HRMS and NMR experiments have been performed to confirm the formation of the interlocked structures. Keywords: active-metal template; clipping; copper(I)-catalyzed alkyne
  • –azide cycloaddition; mechanically interlocked structures; [2]rotaxanes; Introduction Since its birth, in the late sixties [1][2][3], the field of mechanically interlocked molecules (MIMs), including rotaxanes, has gained significant attention culminating by recognition with a Nobel prize in Chemistry
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Published 20 Nov 2023

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

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  • 2004, Takata and co-workers synthesized thiazolium-based chiral [2]rotaxanes as catalysts for the asymmetric benzoin condensation [56][57]. For the synthesis of the rotaxane, ammonium salts 34a/b and the BINOL-based macrocycle (R)-12 were interlocked via tributylphosphine-catalyzed acylative end
  • catalysts (e.g., (S)-49), based on intermolecular interactions that are relevant especially at higher catalyst loadings [61]. Subsequently, our working group reported the synthesis and application of the BINOL-based [2]rotaxanes (S)-56 and (S)-57 [62]. For their synthesis, the phosphoric acid macrocycles (S
  • -workers, with a strong focus on using rotaxanes with halogen-bond (XB) donors that act as binding sites for anionic guest molecules [23]. In 2017, Beer and co-workers reported the synthesis of the BINOL-containing chiral [2]rotaxanes 64 and their application for enantioselective anion recognition [63
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Published 06 May 2022

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

  • Henrik Hupatz,
  • Marius Gaedke,
  • Hendrik V. Schröder,
  • Julia Beerhues,
  • Arto Valkonen,
  • Fabian Klautzsch,
  • Sebastian Müller,
  • Felix Witte,
  • Kari Rissanen,
  • Biprajit Sarkar and
  • Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

Graphical Abstract
  • differential pulse voltammetry (DPV) and compared to those of their corresponding pseudo[2]rotaxanes. Additionally, we report the synthesis of a novel NDI-[2]rotaxane and study the impact of the mechanical bond on the optoelectronic properties of the NDI unit by CV and spectroelectrochemical measurements
  • complexes. All possible pseudo[2]rotaxanes show strongly enthalpy-driven binding – with the notable exception of NDIC7 (Table 1). The unfunctionalized crown ethers BC7 and DBC8 are the strongest binders among the corresponding derivatives with ΔG0 of −34.6 kJ/mol and −34.8 kJ/mol, respectively (Table 1
  • binding entropies in pseudo[2]rotaxanes of A2·PF6 as compared to those formed from A1·PF6. Furthermore, the three crown-7 macrocycles BC7, exTTFC7, and TTFC7 bind A2·PF6 with a binding energy (entries 1, 2, and 4 in Table 1) slightly higher than the crown-8 analogs (entries 5, 6, and 8 in Table 1
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Published 20 Oct 2020

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

Graphical Abstract
  • groups due to the anion binding, including chloride and other oxoanion salts. They also proved that the anions binding strength falls in line with their basicity as seen in the series AcO− > H2PO4− > Cl− > SO42− >NO3−. 2.5. 1,2,3-Triazolium macrocycles and [2]rotaxanes Supramolecular interactions could
  • (chalcogen = Se, Te) motif as a novel ChB donor for anion binding. By exploiting the possibility of the chalcogen atoms to orient within the macrocycle cavity to chelate the copper(I) endotopically, the first examples of mechanically interlocked [2]rotaxanes containing ChB donor groups has been prepared via
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Published 12 Sep 2019

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

Graphical Abstract
  • minimum-energy structure of (4+)36 obtained by molecular mechanics calculations (Figure 8). As it is known [17][18], the threading of directional (or constitutionally asymmetric) alkylbenzylammonium axles with directional calixarene-wheels, could generate two diastereoisomeric pseudo[2]rotaxanes (Figure 9
  • a central 1,3,5-trimethylbenzene moiety. We have shown that 6 is able to give multiple-threading processes in the presence of dipentylammonium or dibenzylammonium axles. The formation of pseudo[2]rotaxanes, pseudo[3]rotaxanes, and pseudo[4]rotaxanes in CDCl3 solution was ascertained by 1D and 2D NMR
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Published 03 Sep 2019

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

Graphical Abstract
  • ] 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
  • conformations is an outward directed NH residue. Solution-state NMR data suggests that the surrounding tetralactam in these [2]rotaxanes undergoes rapid exchange between these different conformations, a dynamic process that has been called macrcocyle breathing, and that there is also simultaneous co
  • are omitted for clarity. Selected X-ray structures of [2]rotaxanes with tetralactam A as the surrounding macrocycle reported by groups led by Leigh, Smith, Cooke, and Berná [37][39][50][52][53][54][55][56]. (a) Chemical structures of squaraine, thiosquaraine, croconaine, and acene guests that can bind
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Published 09 May 2019

Mechanochemistry of supramolecules

  • Anima Bose and
  • Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

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  • synthesis of pillar[5]arene-containing [2]rotaxanes (Figure 8). Mixing a 2:1 ratio of pillar[5]arene (wheel) with dodecanedioyl dichloride (axle) in CHCl3 resulted in the formation of pseudorotaxane 16 which was further treated with different amines (stopper) in a stainless-steel jar with 4 steel balls
  • –acceptor [2]rotaxanes such as 19 through liquid-assisted mechanochemical milling (Figure 9). The donor–acceptor interaction between the electron-deficient naphthalene diimide moiety and the electron-rich naphthalene moieties embedded in the macrocyclic polyethers played the vital role for the construction
  • of unsymmetrically substituted azobenzene [58]. a) Schematic representation for the construction of a [2]rotaxane. b) Chiu’s ball-milling approach for the synthesis of [2]rotaxanes. Mechanochemical synthesis of the smallest [2]rotaxane. Solvent-free mechanochemical synthesis of pillar[5]arene
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Published 12 Apr 2019

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

Graphical Abstract
  • groups of Becher and Stoddart reported on a series of similar, but non-degenerate [2]rotaxanes [74][75]. After several structural optimizations, the bistable rotaxane 14 with a high switching efficiency was reported in 2003 (Figure 12) [76]. In the unswitched state, host 3 is located at the TTF binding
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Published 20 Aug 2018

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

Graphical Abstract
  • stereoisomeric directional pseudo[2]rotaxanes, rotaxanes, and catenanes. Also in this case [38], we were able to obtain a stereoselective threading of the cone calix[6]arene-wheel with alkylbenzylammonium axles (Figure 4b), in which the endo-alkyl pseudo[2]rotaxane stereoisomer was the favoured one [38]. The
  • [2]rotaxanes 2+1cone and 2+11,2,3-alt. 1H NMR spectra (600 MHz, CDCl3, 298 K) of, from bottom to top: hexahexyloxycalix[6]arene 1; a 1:1 mixture (0.003 M) of 1 and 2+·TFPB– immediately after mixing; after 10 h; after 18 h. DFT-optimized structures of the: (left) 2+1cone and (right) 2+11,2,3-alt
  • formation of the two atropoisomeric pseudo[2]rotaxanes 3+1cone and 3+11,2,3-alt. Synthesis of threads 2+ and 3+. Reagents and conditions: a) hexamethyldisilazane, LiClO4, 30 min, 60 °C; b) CH3OH, NaBH4, 2 h, 25 °C; c) TFPBNa, dry MeOH, 25 °C, 18 h. Supporting Information Supporting Information File 408: VT
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Published 14 Aug 2018

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

Graphical Abstract
  • derivatize, [2]rotaxanes are deemed easier to fine-tune from a structural perspective than [2]catenanes. Although we were able to create an optically sensitive [2]catenane molecular shuttle with the bis(pyridinium)ethane and benzylanilinium recognition motifs, we could not achieve the true ON/OFF, bistable
  • molecular switching previously observed for analogous [2]rotaxanes. Experimental General comments 4-Bromobenzyl bromide, 4-bromoaniline, 4-pyridylboronic acid, 1,3-dichlorobenzene, p-tolylmagnesium bromide, n-butyllithium and N-bromosuccinimide were purchased from Aldrich and used as received. Benzoyl
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Published 25 Jul 2018
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