Template routes to interlocked molecular structures and orderly molecular entanglements

Hubin, Timothy J.; Busch, Daryle H.

doi:10.1016/s0010-8545(99)00242-8

Cited by 379 publications

(193 citation statements)

References 106 publications

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confidence: 99%

“…[1][2][3][4][5][6][7][8][9] A large number of main-chain polyrotaxanes have been synthesized to date, along with several side-chain ones (Scheme 1). [1][2][3][4][5][6][7][8][9][10][11][12] Meanwhile, there are few reports on polyrotaxanes with backbones consisting of mechanical bonds as well as poly [2]catenanes. [13][14][15][16][17][18][19][20] Several groups have recently reported attempts to synthesize poly- [2]rotaxanes (daisy chains), obtaining cyclic dimers or trimers instead of the polymers.…”

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First poly[3]rotaxane synthesized through the noncovalent step‐growth polymerization of a homoditopic dumbbell compound and a macrocycle with a reversible thiol–disulfide interchange reaction

Oku

Furusho

Takata

2002

J. Polym. Sci. A Polym. Chem.

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Recent advances in synthetic supramolecular chemistry have led to an outburst of reports on interlocked macromolecules, such as polyrotaxanes. [1][2][3][4][5][6][7][8][9] A large number of main-chain polyrotaxanes have been synthesized to date, along with several side-chain ones (Scheme 1). [1][2][3][4][5][6][7][8][9][10][11][12] Meanwhile, there are few reports on polyrotaxanes with backbones consisting of mechanical bonds as well as poly[2]catenanes. [13][14][15][16][17][18][19][20] Several groups have recently reported attempts to synthesize poly-[2]rotaxanes (daisy chains), obtaining cyclic dimers or trimers instead of the polymers. [21][22][23][24][25] Therefore, the synthesis of this type of polyrotaxane is not only challenging but also promising for creating new polymer materials with unique physical properties. Recently, we reported a new synthetic method for [2]rotaxane (6) and [3]rotaxane (5) under thermodynamic control, which uses the reversible cleavage-recombination process of the disulfide bond in the presence of a catalytic amount of thiol. 26 -30 The yields of the rotaxanes can be well controlled by the solvent, concentration, and temperature because the whole process is reversible. Important features of this method are the efficient thioldisulfide interchange reaction under mild conditions and the tolerance of disulfide for many functional groups. [31][32][33][34] Therefore, this method is promising for the synthesis of more complex molecules such as polyrotaxanes. We report here the first synthesis of poly-[3]rotaxane (3) by the application of this method to homoditopic molecules. 35 Biscrown ether (2) was synthesized from dibenzo-24-crown-8 ether in four steps, 36 whereas bisammonium salt, with a disulfide bond at the center (1), was prepared according to our method (Scheme 2). 26 A CDCl 3 / CD 3 CN mixed solvent system was chosen to study the polymerization of 1 and 2: CD 3 CN confers solubility on 1, whereas CDCl 3 ensures the high stability constants of the complexation and improves the solubility of 2. We carried out the polymerization by allowing a mixture of 1 (0.10 M), 2 (0.10 M), and a catalytic amount of benzenethiol (0.004 M) in CDCl 3 /CD 3 CN (7/3) to stand at 50°C for 7 weeks. The resulting mixture was cooled and kept at room temperature until the system reached equilibrium (2 weeks). The progress of the polymerization was monitored by 1 H NMR, from which the degree of polymerization (DP) was estimated to be 7 (calculated from the rotaxanated ratio of 86%) at the equilibrium state. 37 The evaporation of the solvent gave 3 as a colorless solid. A gel permeation chromatography (GPC) analysis of 3 (with CHCl 3 as a solvent) showed a bimodal distribution, as shown in Figure 1. The number-average molecular weight (M n ) of the mixture was estimated to be 1.6 kg mol Ϫ1 , which was much smaller than 6.8 kg mol Ϫ1 , the value expected from the 1 H NMR spectrum. The retention time of the lower molecular weight part (LMW) was a little shorter than that

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confidence: 99%

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confidence: 99%

First poly[3]rotaxane synthesized through the noncovalent step‐growth polymerization of a homoditopic dumbbell compound and a macrocycle with a reversible thiol–disulfide interchange reaction

Oku

Furusho

Takata

2002

J. Polym. Sci. A Polym. Chem.

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“…T he synthesis and study of interlocked or mechanically bonded supramolecular species, known as rotaxanes, catenanes, and knots, has become an area of increasing interest in the last decade (1)(2)(3)(4). This interest is largely because of the continuing emergence of effective template methods for their construction and the unique properties of the resulting ensembles-properties which, in many cases, are tied to the manipulation of the residual template effects used to construct them (5)(6)(7)(8)(9)(10).…”

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Anion recognition as a method for templating pseudorotaxane formation

Wisner

Beer

Berry

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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Two thread-shaped cations, pyridinium nicotinamide and imidazolium, as their chloride and hexafluorophosphate salts, were studied with regards to complexation with hydrogen-bonddonating acyclic and macrocyclic ligands. In the latter case, the cations form pseudorotaxanes templated by the chloride anion but not hexafluorophosphate. This formation is a function of the coupling of ion-pairing between the cation and chloride anion and subsequent recognition of the anion by the macrocyclic diamide, which provides the driving force for interpenetration. We propose that this anion template principle is a general method for the construction of pseudorotaxanes and could be applied to other cationic threads, anions, and macrocyclic species.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Most polyrotaxanes contain a cyclodextrine or crown ether as the wheel components. Crownether-based polyrotaxanes are easily identifiable by nuclear magnetic resonance (NMR) measurements and have a distinctive structure that provides a simple motif for the evaluation of characteristic properties of the mechanical linkage.…”

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confidence: 99%

Polymer architectures assisted by dynamic covalent bonds: synthesis and properties of boronate-functionalized polyrotaxane and graft polyrotaxane

Koyama

Suzuki

Asakawa

et al. 2011

Polym J

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Poly [2]rotaxane and graft polyrotaxane were synthesized from a mixture of poly(crown ether) (polyester-10 and polyisoxazole-13) as a trunk polymer, boronic-acid-terminated secondary ammonium salt 5 as an axle component, and diol as an end-capping group by pseudorotaxane formation and subsequent catalyst-free dehydrative bondage between the boronic acid and the diol moieties. Trunk polymers 10 and 13 were prepared by copolymerization of diol-or diyne-substituted dibenzo-24-crown-8-ether 9 or 11 and ditopic comonomers such as bifunctional acid dichloride and nitrile N-oxide. The use of the sufficiently bulky and stable homoditopic nitrile N-oxide 12 gave the high-molecular-weight isoxazole-containing poly(crown ether) 13 efficiently and without accidental penetration of the propagation end into the crown cavity, which would have caused gelation. The treatment of these poly(crown ether)s with boronic acid 5 in CH 2 Cl 2 gave the corresponding polypseudorotaxanes, and subsequent graftonto reaction with pinacol and a polymeric terminal diol gave poly[2]rotaxane and graft polyrotaxane. The chemical stability of these supramolecular architectures primarily depends on the bulkiness of the diol group as the end-capping moiety and the inherence originating from the dynamic covalent bond of boronate, as determined by detailed 1 H nuclear magnetic resonance study of model [2]rotaxanes 6-8 and the dissociation behavior of the polymers.

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Template routes to interlocked molecular structures and orderly molecular entanglements

Cited by 379 publications

References 106 publications

First poly[3]rotaxane synthesized through the noncovalent step‐growth polymerization of a homoditopic dumbbell compound and a macrocycle with a reversible thiol–disulfide interchange reaction

First poly[3]rotaxane synthesized through the noncovalent step‐growth polymerization of a homoditopic dumbbell compound and a macrocycle with a reversible thiol–disulfide interchange reaction

Anion recognition as a method for templating pseudorotaxane formation

Polymer architectures assisted by dynamic covalent bonds: synthesis and properties of boronate-functionalized polyrotaxane and graft polyrotaxane

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