Deslipping of Rotaxanes with Axle Center Pieces of Different Lengths

Linnartz, Petra; Schalley, Christoph A.

doi:10.1080/1061027042000204010

Cited by 16 publications

(8 citation statements)

References 15 publications

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“…Early studies on the deslipping of Hunter–Vögtle rotaxanes having a tetraanilide-based macrocycle revealed that a proper size complementarity of the macrocyclic cavity and the stoppers is required for guaranteeing their structural integrity and avoiding the dethreading of the axis from the molecule. , In addition, Schalley et al also deepened into similar interlocked systems, showing that small structural changes in the thread (including variations on its length, flexibility, or connectivity of their stoppers) have a significant impact on the deslippage process. − Although the macrocyclic hollow of the benzylic amide ring of the Leigh-type rotaxanes is notably lesser than the aforementioned, a study of the size complementarity has been never accomplished with these compounds.…”

Section: Resultsmentioning

confidence: 99%

Dethreading of Tetraalkylsuccinamide-Based [2]Rotaxanes for Preparing Benzylic Amide Macrocycles

et al. 2015

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The dethreading of a series of succinamide-based [2]rotaxanes bearing benzylic amide macrocycles is reported herein. These transformations proceeded quantitatively either under flash vacuum pyrolysis, conventional heating, or microwave irradiation. Studying the size complementarity of the stoppers at the ends of the thread and the cavity of the macrocycle allowed us to set up the best substituents for implementing the extrusion of the thread from the interlocked precursors. A variety of (1)H NMR kinetic experiments were carried out in order to evaluate the rate constants of the dethreading process, the half-life times of the rotaxanes, and the influence of temperature and solvents on these processes. The use of dibutylamino groups as stoppers yielded the rotaxane precursor in a reasonable yield and allowed the quantitative deslipping of the rotaxane. The overall process, including the rotaxane formation and its further dethreading, has been exploited for preparing benzylic amide macrocycles enhancing, in most cases, the results of the classical (2 + 2) condensation and other reported stepwise syntheses. The kinetics of the dethreading process is fairly sensitive to the electronic effects of the substituents on the isophthalamide unit or to the electronic nature of the pyridine rings through a conformational equilibrium expanding or contracting the cavity of the interlocked precursor.

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Section: Resultsmentioning

confidence: 99%

Dethreading of Tetraalkylsuccinamide-Based [2]Rotaxanes for Preparing Benzylic Amide Macrocycles

et al. 2015

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“…11 and 6, are favored over the open-chain analogue 2, which likely exists in an extended conformation. The latter seems unfit for the assumed formation of the likely hydrogen bonds between the analyte and the macrocycles 11 and 6 [14]. The catenane 10, whose cavities are mutually blocked by the other wheel, shows practically no sensitivity to acrylamide.…”

Section: Resultsmentioning

confidence: 99%

Quartz Microbalance Sensor for the Detection of Acrylamide

Kleefisch

Kreutz

Bargon

et al. 2004

Sensors

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Several macrocycles of the Hunter-Vögtle type have been identified as superior host compounds for the detection of small amounts of acrylamide. When coated onto the surface of a quartz microbalance, these compounds serve as highly sensitive and selective sensor-active layers for their use in electronic noses. In this study, differently substituted macrocycles were investigated including an open-chain analogue and a catenane. Their structure and functional groups are correlated with their observed affinities to acrylamide and related acids and amides. The much smaller response of the open-chain compound and the almost absent sensor response of the catenane suggest that binding occurs within the cavity of the macrocycle. Theoretical calculations agree well with the experimental data even though they do not yet take into account the arrangement of the macrocycles in the sensor-active layer. The lower detection limit of acrylamide is 10 parts per billion (ppb), which is impressively low for this type of sensor. Other related compounds such as acrylic acid, propionamide, or propionic acid show no or significantly lower affinities to the macrocycles in these concentration ranges.

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“…Consequently, ether rotaxanes are well suited for a study of their deslipping behavior and the effects of small structural changes on it. As a first step, rotaxanes with alkyl chains of different lengths in the axle center piece were studied with respect to their deslipping kinetics [254]. These experiments intended to test the validity of the simple model that a rotaxane is just a thin filament threaded through the cavity of a macrocycle equipped with two bulky stopper groups that prevent deslipping.…”

Section: Deslippage As a Precision Tool For The Measurement Of Stericmentioning

confidence: 99%