Arnaud Tron’s research while affiliated with University of Bordeaux and other places

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Publications (1)


UV‐Vis absorption spectra of trans‐chalcone 1 (30 μM) in the presence of increasing concentrations of CB7 in water (pH≈6.3). Inset: Absorbance at 370 nm on adding increasing amounts of CB7.
¹H NMR spectra of 1 (0.5 mM) in the presence of increasing concentrations of CB7 in D2O. Upon addition of CB7, the ¹H NMR signals of 1 show considerable broadening likely due to intermediate exchange between free and complexed species with different co‐conformations and stoichiometries.
(a) UV‐Vis absorption spectra of flavylium 2 (15 μM) in the presence of increasing concentrations of CB7 in water at pH=1. Inset: Absorbance at 462 nm on increasing amount of CB7; (b) Emission spectra of flavylium 2 (0.5 μM) in the presence of increasing concentrations of CB7 in water at pH=1 (λex=430 nm, excitation slits=9 nm, emission slits=4.5 nm). Inset: observed fluorescence quantum yield on increasing amount of CB7. Traced blue line is the fitting to a 1 : 1 model (K1:1=1.5×10⁸ M⁻¹) and the red line to a sequential 2 : 1 model.
¹H NMR spectra of 2 (1.5 mM) in the presence of increasing concentrations of CB7 in D2O at pD=1 ([DCl]=0.1 M). Contrary to 1, in this case the slow exchange between free and complexed species with defined stoichiometry and co‐conformation leads to the observation of sharper signals in the ¹H NMR spectra. * denotes a minor impurity.
UV‐Vis absorption spectra of equilibrated solutions of 1 (18 μM) in the presence of 1 equivalent of CB7 in 10 mM of aqueous citrate buffer at different pH values. Inset: Absorbance at 456 nm as a function of pH.

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Light‐ and pH‐regulated Water‐soluble Pseudorotaxanes Comprising a Cucurbit[7]uril and a Flavylium‐based Axle
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October 2021

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126 Reads

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7 Citations

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Shilin Yu

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Arnaud Tron

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[...]

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A linear double pyridinium‐terminated thread comprising a central chalcone moiety is shown to provide two independent binding sites with similar affinity for cucurbit[7]uril (CB7) macrocycles in water as judged from NMR, UV‐Visible and fluorescence spectroscopies. Association results in [2] and [3]pseudorotaxanes, which are both pH and photosensitive. Switching from the neutral chalcone to the cationic flavylium form upon irradiation at 365 nm under acidic conditions provided an enhanced CB7 association (K1:1 increases from 1.2×10⁵ M⁻¹ to 1.5×10⁸ M⁻¹), limiting spontaneous on‐thread cucurbituril shuttling. This co‐conformational change in the [2]pseudorotaxane is reversible in the dark with kobs=4.1×10⁻⁴ s⁻¹. Threading the flavylium moiety into CB7 leads to a dramatic increase in the fluorescence quantum yield, from 0.29 in the free axle to 0.97 in the [2]pseudorotaxane and 1.0 in the [3]pseudorotaxane.

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Citations (1)


... The acidity change of guest compounds upon encapsulation was used to construct pH-triggered self-sorting system [18]. The shuttling motion and the relative position of the constituents were regulated with pH in pseudorotaxanes based on cucurbit [7]uril (CB7) [19][20][21]. ...

Reference:

Kinetics of base-promoted transformation of berberrubine-cucurbit[7]uril inclusion complex: Active role of alkali cations
Light‐ and pH‐regulated Water‐soluble Pseudorotaxanes Comprising a Cucurbit[7]uril and a Flavylium‐based Axle