Size Complementarity of Macrocyclic Cavities and Stoppers in Amide-Rotaxanes

Heim, Christiane; Affeld, Ansgar; Nieger, Martin; Vögtle, Fritz

doi:10.1002/(sici)1522-2675(19990505)82:5<746::aid-hlca746>3.0.co;2-c

Cited by 71 publications

(31 citation statements)

References 3 publications

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“…5-Tert-butyl isophthaloyl chloride was synthesized as previously reported [13] and sublimated before use. Solvents and other reactants were of reagent-grade quality, and used without further purification.…”

Section: Experimental Partmentioning

confidence: 99%

Soluble Polyamides and Polyimides Functionalized with Benzo‐15‐Crown‐5‐Pendant Groups

Maya

Lozano

Campa

et al. 2004

Macromol. Rapid Commun.

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Summary: A new diamine monomer containing a crown ether was made to react with commercial diacid chlorides and dianhydrides to yield new aromatic polyamides and polyimides. The crown ether moiety was introduced as a pendant group so that the polymers showed enhanced solubility in organic solvents, good thermal properties (high transition temperatures and high thermal stability), and good film‐forming ability.

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Section: Experimental Partmentioning

confidence: 99%

Soluble Polyamides and Polyimides Functionalized with Benzo‐15‐Crown‐5‐Pendant Groups

Maya

Lozano

Campa

et al. 2004

Macromol. Rapid Commun.

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“…Previous stilbene rotaxanes have been prepared by aromatic nucleophilic substitution 4 and by slipping macrocycles over pre-formed dumbbells. 5 Six new rotaxanes 1b-g have been prepared by reacting bulky water-soluble aryl iodides 2a and 2b with diboronic acids 3a-c 6 in the presence of cyclodextrins (a-CD and b-CD; ca. 5 eq.…”

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confidence: 99%

Synthesis of fluorescent stilbene and tolan rotaxanes by Suzuki coupling

et al. 2001

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Highly fluorescent stilbene and tolan cyclodextrin [2]rotaxanes have been synthesised in good yield using aqueous Suzuki coupling, and the crystal structure of one of these rotaxanes has been determined.A rotaxane is a supramolecular assembly of a dumbbell locked through the cavity of a macrocycle. 1 The formation of rotaxanes provides a means of stabilising dumbbell-shaped chromophores, by shielding them from the external environment. This type of encapsulation can also enhance the fluorescence efficiency. 2 Hydrophobic binding is a convenient way of directing rotaxane formation, provided the dumbbell can be synthesised in water. Recently we reported the synthesis of poly-p-phenylene rotaxanes and polyrotaxanes using aqueous Suzuki coupling, although in this case the [2]rotaxane (1a in Table 1) was only obtained in low yield (4%). 3 While exploring the scope of this route to rotaxanes, we discovered that the right combinations of aryl iodide stopper, diboronic acid core and macrocycle components give highly fluorescent cyclodextrin encapsulated stilbenes and tolans, such as 1g, in high yield. Previous stilbene rotaxanes have been prepared by aromatic nucleophilic substitution 4 and by slipping macrocycles over pre-formed dumbbells. 5 Six new rotaxanes 1b-g have been prepared by reacting bulky water-soluble aryl iodides 2a and 2b with diboronic acids 3a-c 6 in the presence of cyclodextrins (a-CD and b-CD; ca. 5 eq.), in aq. sodium carbonate containing palladium(II) acetate, as summarised in Scheme 1 and Table 1. † As expected, the 5-iodoisophthalic acid stopper 2b is too narrow to form rotaxanes with b-CD, and the biphenyl diboronic acid core 3a is too bulky to form rotaxanes with a-CD. Apart from these exceptions, all combinations of aryl iodides, diboronic acids and macrocycles yield rotaxanes. The lower yields obtained with the 1-iodonaphthalene-3,6-disulfonate stopper 2a can be attributed to an unfavourable interaction between the bound CD and the inwardly pointing H8 of the naphthalene. The tetracarboxylate Table 1 Yields for rotaxane synthesis, and fluorescence behaviour of rotaxanes and dumbbells a Scheme 1 This journal is

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“…For this study, we limit our attention to pseudorotaxane formation between aminecontaining axle molecules and macrocycles containing ether linkages. Pseudorotaxane amide systems has been investigated (36,37) and show that complementary hydrogen bonding between the amide macrocycle and the linear amide threading group is a requirement for high yield of the rotaxane and further established the pseudorotaxane as the intermediate of prime importance. Measurements of the effect of substitution at the phenyl ring of dibenzylamine on pseudorotaxane formation (38) revealed the inhibiting effect of electron-donating substituents, reducing the hydrogen bond donating ability of the threading groups.…”

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confidence: 99%

Factors affecting the threading of axle molecules through macrocycles: Binding constants for semirotaxane formation

Clifford

Abushamleh

Busch

2002

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

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The threading of more or less linear axle molecules through macrocyclic molecules, a fundamental process relating to the formation of interlocked molecular structures, has been investigated through the study in acetone of the equilibrium constants for the formation of pseudorotaxanes by NMR methods. The 30 new axle molecules have in common a secondary ammonium group, present as the thiocyanate salt, and an anthracen-9-ylmethyl group, but are rendered unique by the second amine substituent. All rotaxanes involve the well known polyether macrocycle, benzo[24]crown-8. The constants for the binding of axles having linear groups ranging from 2 to 18 carbon atoms show little variation in binding constant but are divided into two groups by their equilibration rates. Those with less than five methylene groups react rapidly on the NMR timescale, whereas those having more than five methylene groups are slow. Branching inhibits binding, but the effect decreases as the branch is moved away from the amine. Phenyl groups weaken binding when close to the amine but strengthen binding when more remote. Some functional groups decrease pseudorotaxane stability (alcohol functions), whereas others increase binding (carboxylic acid groups).

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Size Complementarity of Macrocyclic Cavities and Stoppers in Amide-Rotaxanes

Cited by 71 publications

References 3 publications

Soluble Polyamides and Polyimides Functionalized with Benzo‐15‐Crown‐5‐Pendant Groups

Soluble Polyamides and Polyimides Functionalized with Benzo‐15‐Crown‐5‐Pendant Groups

Synthesis of fluorescent stilbene and tolan rotaxanes by Suzuki coupling

Factors affecting the threading of axle molecules through macrocycles: Binding constants for semirotaxane formation

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