Aqueous solubilization of photochromic compounds by bile salt aggregates

Li, Rui; Santos, Cerize S.; Norsten, Tyler B.; Morimitsu, Kentaro; Bohne, Cornelia

doi:10.1039/b926351a

Cited by 29 publications

(42 citation statements)

References 23 publications

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“…Similar kinetics with biexponential “rise and decay” behavior have been observed for other spiropyran derivatives. 40,45 As the p K a -values of the SPH + and the MCH + forms of 1 were determined to 0.4 and 3.7, respectively, the concentrations of the protonated forms are negligible at pH 7 (see Table 1 for the p K a -values of derivatives 1 – 6 ). Hence, our kinetic model at this pH includes the species SP, MC, and HP.…”

Section: Resultsmentioning

confidence: 99%

Characterization of the Thermal and Photoinduced Reactions of Photochromic Spiropyrans in Aqueous Solution

et al. 2013

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Six water-soluble spiropyran derivatives have been characterized with respect to the thermal and photoinduced reactions over a broad pH-interval. A comprehensive kinetic model was formulated including the spiro- and the merocyanine isomers, the respective protonated forms, and the hydrolysis products. The experimental studies on the hydrolysis reaction mechanism were supplemented by calculations using quantum mechanical (QM) models employing density functional theory. The results show that (1) the substitution pattern dramatically influences the pKa-values of the protonated forms as well as the rates of the thermal isomerization reactions, (2) water is the nucleophile in the hydrolysis reaction around neutral pH, (3) the phenolate oxygen of the merocyanine form plays a key role in the hydrolysis reaction. Hence, the nonprotonated merocyanine isomer is susceptible to hydrolysis, whereas the corresponding protonated form is stable toward hydrolytic degradation.

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Section: Resultsmentioning

confidence: 99%

Characterization of the Thermal and Photoinduced Reactions of Photochromic Spiropyrans in Aqueous Solution

et al. 2013

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“…The complex aggregation behavior has been studied by several experimental and theoretical methods [2][3][4] which lead to the proposal of several models and among them the primary and the secondary aggregate models suggested by Small and colleagues are the widely accepted ones. Due to this unique aggregation behavior, bile salt has the ability to solubilize various biologically active organic guest molecules, which include many sparingly water soluble drug molecules, [6][7][8][9][10][11][12][13][14] and finally it helps to control various chemical reactions such as photoinduced, enzymatic and complexation reactions. Primary aggregates (with hydrophobic binding sites) are formed at lower concentrations of bile salts, consisting of 2-9 monomers and they are stabilized by the hydrophobic interaction between the convex sides of the monomers.…”

Section: Introductionmentioning

confidence: 99%

Modulation of the aggregation properties of sodium deoxycholate in presence of hydrophilic imidazolium based ionic liquid: water dynamics study to probe the structural alteration of the aggregates

Kundu

Banik

Roy

et al. 2015

Phys. Chem. Chem. Phys.

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In this article, we have investigated the effect of a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]-BF4), on the aggregation properties of a biological surfactant, sodium deoxycholate (NaDC), in water. In solution, unlike conventional surfactants it shows stepwise aggregation and the effect of the conventional ionic liquid on the aggregation properties is rather interesting. We have observed concentration dependent dual role of the ionic liquid; at their low concentration, the aggregated structure of NaDC reorganizes itself into an elongated rod like structure. However, the aggregated network is disintegrated into small aggregates upon further addition of ionic liquid. TEM (Transmission Electron Microscopy), SEM (Scanning Electron Microscopy) and FLIM (Fluorescence Lifetime Imaging Microscopy) images also confirmed the structural alteration of NaDC upon varying the concentration of the ionic liquid. The proton NMR data indicate that hydrophobic as well as electrostatic interaction is solely responsible for such structural adaptation of NaDC in the presence of an ionic liquid. The host-guest interaction inside the aggregates is monitored using Coumarin-153 (C-153) and the location of C-153 is probed by varying the excitation wavelength from 375 nm to 440 nm and the two binding sites of the aggregates are affected in a different fashion in the presence of ionic liquid. Excitation in the blue region selects the fluorophores which preferably bind to the buried region of the aggregates, whereas 440 nm excitation corresponds to the guest molecules which are exposed to the solvent molecules. The average solvation time of C-153 is increased in the presence of 1.68 wt% [bmim]-BF4 at λexc = 440 nm i.e. the probe molecules relocate themselves to a more restricted region. However, the average solvation time became 2.6 times faster in the presence of 11.2 wt% [bmim]-BF4, which corresponds to a more polar and exposed region. The time resolved anisotropy measurements and polarity determined by pyrene also supported our results in addition to solvation dynamics measurements. In summary, ionic liquids can modulate the host-guest interaction of bile salt aggregates, which can be used as nanocarriers for drug delivery.

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“…Based on these data it becomes clear that the described molecular design based on an anchor approach constitutes a viable strategy for extraordinary merocyanine stabilization. [32,64,71] This becomes even more evident when considering the highly desirable conservation of the photochromic properties as will be discussed in the following section.…”

Section: MCmentioning

confidence: 98%

“…Similar kinetics with a biexponential "rise and decay" behaviour have been reported for related spiropyrans. [63,64] In our case this fitting yielded a rise time constant of  1 = 6.5 h, corresponding to a rate constant of k 1 = 4.3 × 10 5 s…”

Section: Acido-and Photochromic Behavior Of Spiropyran 1 In Aqueous Smentioning

confidence: 99%

Switching Properties of a Spiropyran–Cucurbit[7]uril Supramolecular Assembly: Usefulness of the Anchor Approach

Nilsson

Carvalho

et al. 2012

ChemPhysChem

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A nitrospiropyran, which was modified with a cadaverine-derived anchor, was investigated with respect to its thermally-induced isomerizations, hydrolytic stability of the merocyanine form, and the photochromic ring closure. The host-guest complexation of the anchor by the cucurbit [7]uril macrocycle, evidenced by absorption titration, NMR spectroscopy, and electrospray ionization mass spectrometry, produced significant improvements of the switching properties of the photochrome: a) a ca. 70 times faster appearance of the merocyanine form, b) a practically unlimited hydrolytic stability of the merocyanine (two and a half days without any measureable decay), and c) a fast, clean, and fatigueresistant photoinduced ring-closure back to the spiro form. The importance of an adequate molecular design of the anchor was demonstrated by including control experiments with spiropyrans with a shorter linker or without such structural asset.

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Aqueous solubilization of photochromic compounds by bile salt aggregates

Cited by 29 publications

References 23 publications

Characterization of the Thermal and Photoinduced Reactions of Photochromic Spiropyrans in Aqueous Solution

Characterization of the Thermal and Photoinduced Reactions of Photochromic Spiropyrans in Aqueous Solution

Modulation of the aggregation properties of sodium deoxycholate in presence of hydrophilic imidazolium based ionic liquid: water dynamics study to probe the structural alteration of the aggregates

Switching Properties of a Spiropyran–Cucurbit[7]uril Supramolecular Assembly: Usefulness of the Anchor Approach

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