Spacer Length‐Independent Shuttling of the Pillar[5]arene Ring in Neutral [2]Rotaxanes

Ogoshi, Tomoki; Kotera, Daisuke; Nishida, Shungo; Kakuta, Takahiro; Yamagishi, Toshio; Brouwer, Albert M.

doi:10.1002/chem.201800104

Cited by 19 publications

(12 citation statements)

References 38 publications

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“…When n -alkanes were used as the guest, complexation occurred in CDCl 3 23,24 . Thus, the negatively charged oxygen atoms in the PEO chain inhibited the complexation in this case 25 . Next, we investigated the host–guest complexation of PEO with crystals of P5 .…”

Section: Resultsmentioning

confidence: 84%

Molecular weight fractionation by confinement of polymer in one-dimensional pillar[5]arene channels

et al. 2019

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Confinement of polymers in nano-spaces can induce unique molecular dynamics and properties. Here we show molecular weight fractionation by the confinement of single polymer chains of poly(ethylene oxide) (PEO) in the one-dimensional (1D) channels of crystalline pillar[5]arene. Pillar[5]arene crystals are activated by heating under reduced pressure. The activated crystals are immersed in melted PEO, causing the crystals to selectively take up PEO with high mass fraction. The high mass fractionation is caused by the greater number of attractive CH/π interactions between PEO C-H groups and the π-electron-rich 1D channel of the pillar[5]arene with increasing PEO chain length. The molecular motion of the confined PEO (PEO chain thickness of ~3.7 Å) in the 1D channel of pillar[5]arenes (diameter of ~4.7 Å) is highly restricted compared with that of neat PEO.

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Section: Resultsmentioning

confidence: 84%

Molecular weight fractionation by confinement of polymer in one-dimensional pillar[5]arene channels

et al. 2019

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“…These results suggest that the passage of the ammonium group (more generally the substrate) through the PA cavity determines, at least to some extent, the binding interactions and, in consequence, the reactivity of hydrazones. In PA5‐COOH , this movement is greatly hampered, and the hydrazones are positioned much firmly.…”

Section: Resultsmentioning

confidence: 91%

Supramolecular Catalysis by Carboxylated Pillar[n]arenes

2020

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Pillar[n]arenes constitute the most recognizable macrocyclic compounds discovered recently. So far, research has been focused on their binding properties, while the catalytic properties were poorly explored. Herein we present the study of the binding as well as the catalytic properties of pillar[5]-and pillar [6]arenes functionalized with carboxylic groups in water. We show that electrostatic stabilization is not the main driving force during the binding, however, it is crucial for catalysis. The macrocycles promote the hydrolysis of a wide variety of hydrazones, and their catalytic activity, in essence, is determined by the barrier of the passage of the substrate through the macrocyclic cavity. This opens up new perspectives for these macrocycles that could make a strong competition to traditional supramolecular catalysts such as cyclodextrins or cucurbiturils.

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“…The association constant of complexation between protonated pyridine and MeP5A in CDCl 3 was determined to be 57.0 ± 1.3 m –1 at 25 °C using a nonlinear curve‐fitting analysis based on the 1 H NMR titration experiments (see SI, section 4 in detail). Considering the association constant was not high as expected, so we chose ethylene glycol chain rather than alkyl chain as a linker connected pyridine and pillar[5]arene . As shown in Scheme , by reacting monohydroxy pillar[5]arene 2 with ethylene glycol bridged pyridine 3 , pseudo[1]rotaxane 1 was synthesized successfully in 20 % yields in anhydrous DMF (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Pillar[5]arene Based Pseudo[1]rotaxane Operating as Acid/Base‐Controllable Two State Molecular Shuttle

et al. 2019

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A ethylene glycol bridged pyridine and pillar[5]arene based mechanically selflocked pseudo[1]rotaxane was constructed successfully. The structure and selflocked conformation of pseudo[1]rotaxane were confirmed by 1H, 2D NMR spectrum and HR‐ESI‐MS. It was found that in dilute solution the pseudo[1]rotaxane could be operated as an acid/base‐controllable two state molecular shuttle while In concentrated solution, the pseudo[1]rotaxane existed as a dimer and could be operated from shrinking state to extension state.

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Spacer Length‐Independent Shuttling of the Pillar[5]arene Ring in Neutral [2]Rotaxanes

Cited by 19 publications

References 38 publications

Molecular weight fractionation by confinement of polymer in one-dimensional pillar[5]arene channels

Molecular weight fractionation by confinement of polymer in one-dimensional pillar[5]arene channels

Supramolecular Catalysis by Carboxylated Pillar[n]arenes

Pillar[5]arene Based Pseudo[1]rotaxane Operating as Acid/Base‐Controllable Two State Molecular Shuttle

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