Separation of C<sub>70</sub> over C<sub>60</sub> and Selective Extraction and Resolution of Higher Fullerenes by Syndiotactic Helical Poly(methyl methacrylate)

Kawauchi, Takehiro; Kitaura, Atsushi; Kawauchi, Mariko; Takeichi, Tsutomu; Kumaki, Jiro; Iida, Hiroki; Yashima, Eiji

doi:10.1021/ja104969a

Cited by 57 publications

(71 citation statements)

References 31 publications

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“…[63] In this context, spectacular results have been reported by Sanders and co-workers with the morphological tuning of amino acid based self-assemblies. [64] The helical structures developed by this team, [65a,b] as well as by the groups of Toniolo [65c] and Kawauchi and Yashima, [66] are extremely promising materials both for the purification of higher fullerenes and for their chiral resolution. These results pave the way for developing efficient and structurally simple materials which will allow the purification of higher fullerenes on larger scales.…”

Section: Discussionmentioning

confidence: 99%

Wraparound Hosts for Fullerenes: Tailored Macrocycles and Cages

2011

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Custom-made macrocyclic receptors for fullerenes are proving a valuable alternative to achieve the affinity and selectivity required to meet challenges such as the selective extraction of higher fullerenes, their chiral resolution, or the self-assembly of functional molecular materials. In this Minireview, we highlight some of the important breakthroughs that this class of fullerene hosts has already produced.

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Section: Discussionmentioning

confidence: 99%

Wraparound Hosts for Fullerenes: Tailored Macrocycles and Cages

2011

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“…The remarkable nature of this system was demonstrated by the controlled construction of responsive and structurally different receptors for different fullerenes (C 60 and C 70 ) within the same reaction mixture. Although several examples of selective fullerene binding/separation have been reported, [10][11][12][13][14][15] the construction of morphologically different fullerene hosts with distinct binding properties by using the dynamic combinatorial approach has not previously been reported. The use of a third component, the proton, to switch between different dynamic combinatorial responses using the same exchange reaction is also new.…”

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confidence: 99%

Proton‐Driven Switching Between Receptors for C₆₀ and C₇₀

et al. 2011

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We describe herein the remarkable, protoninduced transformations of supramolecular "chameleons" based on naphthalenediimides (NDIs). We demonstrate rapid, reversible, and controllable morphological switching between receptors for different fullerenes (C 60 and C 70 ), thus allowing the selective binding of either guest in a mixture of both guests. This work is an extension of the dynamic combinatorial concept [1,2] into a new dimension: using hydrogen bonding as the exchange reaction, the response of the NDI building blocks to the presence of fullerene guests depends on the concentration of protons as a third component. The switching between the two receptors, a nanotube and a hexameric capsule (Figure 1), is under thermodynamic control (i.e., the most stable host-guest complex is dominant) and is triggered by the guest (template) present in solution.In aprotic solvents of medium polarity such as chloroform and dichloromethane, self-recognition through hydrogen bonding causes the amino acid derived NDIs (Scheme 1) to adopt different aggregate forms, depending on the presence or absence of guests. [3][4][5] The NDI nanotubes are held together by classical intermolecular COOH-HOOC hydrogen bonds supplemented by weak CH···O = C bonding (Figure 1 a, c).[3] The hexameric capsule is formed in the presence of C 70 at the expense of the nanotube and is held together by hydrogen bonds between the COOH groups (equator, Figure 1 b) and a rare, threefold hydrogen-bond pattern between the COOH group, an imide C=O group, and an acidic hydrogen atom of NDI at the pole (Figure 1 d). [5] Both of these supramolecular assemblies can therefore be destroyed by offering the NDI units alternative hydrogenbonding interactions. We originally showed that this goal could be achieved by use of a hydrogen-bond-disrupting solvent such as MeOH; this approach has the disadvantage of leading to the permanent destruction of the supramolecules. We now show that morphological switching between nanotube, hexameric receptor, and monomers is readily achieved by simple protonation-deprotonation reactions that result in the formation of dynamic, size-selective fullerene receptors, the structure and recognition properties of which depend on the position of the acid/base equilibrium (Figure 2). This work has also uncovered unexpected differences in the sensitivity to base-induced dissociation of the nanotubes derived from different amino acids. Scheme 1. Naphthalenediimides derived from amino acids used in the present work. Boc = tert-butyloxycarbonyl, Bzl = benzyl, Trt = trityl.

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“…When equal amounts of C 60 and C 70 were mixed in toluene with st-PMMA, st-PMMA preferentially encapsulated C 70 over C 60 with an almost perfect selectivity (99.8%) (Figure 7.9b) [66]. When equal amounts of C 60 and C 70 were mixed in toluene with st-PMMA, st-PMMA preferentially encapsulated C 70 over C 60 with an almost perfect selectivity (99.8%) (Figure 7.9b) [66].…”

Section: Macromolecular Helicity Memory In a Gel And A Solidmentioning

confidence: 99%

“…by a chiral amine (S)-or (R)-52) was found to enantiomer-selectively extract chiral fullerenes (Figure 7.9c) [66]. A series of optically active fullerenes (C 76 , C 84 , C 86 , C 88 , C 90 , C 92 , C 94 , and C 96 ) was extracted from carbon soot, and each higher fullerene was isolated by preparative HPLC.…”

Section: Macromolecular Helicity Memorymentioning

confidence: 99%

Synthesis and Application of Helical Polymers with Macromolecular Helicity Memory

Iida

Yashima

2011

Polymeric Chiral Catalyst Design and Chiral Polymer Synthesis

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Separation of C₇₀ over C₆₀ and Selective Extraction and Resolution of Higher Fullerenes by Syndiotactic Helical Poly(methyl methacrylate)

Cited by 57 publications

References 31 publications

Wraparound Hosts for Fullerenes: Tailored Macrocycles and Cages

Wraparound Hosts for Fullerenes: Tailored Macrocycles and Cages

Proton‐Driven Switching Between Receptors for C₆₀ and C₇₀

Synthesis and Application of Helical Polymers with Macromolecular Helicity Memory

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Separation of C70 over C60 and Selective Extraction and Resolution of Higher Fullerenes by Syndiotactic Helical Poly(methyl methacrylate)

Cited by 57 publications

References 31 publications

Wraparound Hosts for Fullerenes: Tailored Macrocycles and Cages

Wraparound Hosts for Fullerenes: Tailored Macrocycles and Cages

Proton‐Driven Switching Between Receptors for C60 and C70

Synthesis and Application of Helical Polymers with Macromolecular Helicity Memory

Contact Info

Product

Resources

About

Separation of C₇₀ over C₆₀ and Selective Extraction and Resolution of Higher Fullerenes by Syndiotactic Helical Poly(methyl methacrylate)

Proton‐Driven Switching Between Receptors for C₆₀ and C₇₀