Magic Ring Rotaxanes by Olefin Metathesis

Kilbinger, Andreas F. M.; Cantrill, Stuart; Waltman, Andrew W.; Day, Michael; Grubbs, Robert H.

doi:10.1002/anie.200351167

Cited by 133 publications

(43 citation statements)

References 35 publications

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“…4 In the glovebox, sodium hydride (95%, 288 mg, 12 mmol) was added to a 20 mL scintillation vial equipped with a stirbar. The vial was sealed with a pierceable Teflon-lined septum cap and brought out of the glovebox.…”

Section: Synthesis Of C 6 Eo 4 π Monomermentioning

confidence: 99%

Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes

et al. 2016

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We perform a joint experimental and computational study of ion transport properties in a systematic set of linear polyethers synthesized via acyclic diene metathesis (ADMET) polymerization. We measure ionic conductivity, σ, and glass transition temperature, T g, in mixtures of polymer and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. While T g is known to be an important factor in the ionic conductivity of polymer electrolytes, recent work indicates that the number and proximity of lithium ion solvation sites in the polymer also play an important role, but this effect has yet to be systematically investigated. Here, adding aliphatic linkers to a poly(ethylene oxide) (PEO) backbone lowers T g and dilutes the polar groups; both factors influence ionic conductivity. To isolate these effects, we introduce a two-step normalization scheme. In the first step, Vogel–Tammann–Fulcher (VTF) fits are used to calculate a temperature-dependent reduced conductivity, σr(T), which is defined as the conductivity of the electrolyte at a fixed value of T – T g. In the second step, we compute a nondimensional parameter f exp, defined as the ratio of the reduced molar conductivity of the electrolyte of interest to that of a reference polymer (PEO) at a fixed salt concentration. We find that f exp depends only on oxygen mole fraction, x 0, and is to a good approximation independent of temperature and salt concentration. Molecular dynamics simulations are performed on neat polymers to quantify the occurrences of motifs that are similar to those obtained in the vicinity of isolated lithium ions. We show that f exp is a linear function of the simulation-derived metric of connectivity between solvation sites. From the relationship between σr and f exp we derive a universal equation that can be used to predict the conductivity of ether-based polymer electrolytes at any salt concentration and temperature.

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Section: Synthesis Of C 6 Eo 4 π Monomermentioning

confidence: 99%

Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes

et al. 2016

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“…Macrocycles could also be reformed on breaking the hydrogenbonding network in the catenanes by incorporation of (CF 3 CO) 2 O in the presence of catalyst 1. A similar influence of noncovalent interactions in rotaxane [119] and catenane [120] formation was subsequently described by the Grubbs group. Weak perfluorophenyl-phenyl interactions were utilized by Collins and coworkers in the RCM synthesis of paracyclophanes ( Figure 16) [121] The perfluorinated ring present in 20b was proposed to "shield" one side of the cyclophane, orienting both allyl chains in close proximity [122], and enabling RCM in moderate yields (41%).…”

Section: Non-covalent Interactionsmentioning

confidence: 75%

Ring-Closing Metathesis Synthesis of Medium and Large Rings: Challenges and Implications for Sustainable Synthesis

Monfette

Fogg

2010

Green Metathesis Chemistry

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Synthesis of medium-sized and macrocyclic rings by ring closing metathesis (RCM) reactions of dienes involves challenges not found in synthesis of the more common five-and six-membered rings. This review discusses factors that determine the probability and efficiency of cyclization, and experimental methods that have been used to increase selectivity for RCM products, with specific reference to the concentrations at which RCM can be achieved. These issues have important implications for the environmental and economic sustainability of large-scale synthetic processes utilizing RCM for assembly of rings larger than six members.

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“…It has been shown that both structures III and IV can be utilized successfully in the self-assembly of dynamic [2]rotaxanes [164,178,185,200,[208][209]. The reversibly formed component can be located in either the dumbbell (III) or the ring (IV) components, thus allowing for threading-followed-by-stoppering and clipping approaches, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Another important investigation on some interlocked molecular compounds synthesized thermodynamically was recently reported by the Grubbs group [200]. In this work, the well established mutual recognition exhibited by secondary dialkylammonium (R 2 NH 2 + ) ions and suitably sized crown ethers is combined, in an elegant fashion, with the versatile reversible RCM reaction.…”

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confidence: 98%