A dithienylethene-tethered β-cyclodextrin dimer as a photoswitchable host

Mulder, Alart; Juković, Amela; Lucas, Linda N.; Esch, Jan H. van; Feringa, Ben L.; Huskens, Jurriaan; Reinhoudt, David N.

doi:10.1039/b208692a

Cited by 50 publications

(23 citation statements)

References 18 publications

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“…Photochemical reactions were monitored by UV/Vis and 1 H NMR spectroscopy. The absorption spectrum of dimer 9 ( Figure 1) is very similar to that of dimer 4 [14] and is typical for the type of dithienylethene moiety used for the spacing of the dimers. [15] Aqueous solutions of the open forms of both dimers showed strong absorption in the UV region, with absorption maxima at 267 and 254 nm for dimers 4 a and 9 a, respectively.…”

Section: Resultsmentioning

confidence: 63%

“…[14] We have prepared two dithienylethene-tethered b-cyclodextrin dimers (4 and 9) with different connectivities between the cyclodextrins and the photochromic units (Scheme 1). In dimer 4, the dithienylethene moiety is attached directly at the secondary sides of the b-cyclodextrin cavities, which leads to a relatively rigid dimer with most of its rotational freedom in the dithienylethene spacer.…”

Section: Introductionmentioning

confidence: 99%

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Photocontrolled Release and Uptake of a Porphyrin Guest by Dithienylethene‐Tethered β‐Cyclodextrin Host Dimers

Mulder

Juković

Leeuwen

et al. 2004

Chemistry A European J

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Two photoswitchable dithienylethene‐tethered β‐cyclodextrin dimers were synthesized to function as host molecules with an externally controllable binding affinity. The cyclodextrin cavities of these dimers are linked through their secondary sides by a photochromic dithienylethene unit that is connected to the secondary rim either directly (4) or through propyl spacers (9). Irradiation with light switches these dimers between a relatively flexible (open) and a rigid (closed) form. The binding properties of the dimers depend on the configuration of the dithienylethene spacer, as is shown by microcalorimetry performed with tetrakis‐sulfonatophenyl porphyrin (TSPP) as a guest molecule. The differences in binding properties are most pronounced for the more rigid dimer 4, which binds TSPP 35 times more strongly in the open form (4 a) than in the closed form (4 b). The values found for the enthalpy of binding (ΔH°) indicate that this difference in binding is due to the loss of cooperativity between the two β‐cyclodextrin cavities in the closed form. Molecular modeling shows that 4 b is not able to bind TSPP effectively in both cyclodextrin cavities. The open and closed forms of the more flexible dimer 9 show no substantial difference in their binding of TSPP. Thermodynamic values indicative of strong binding of TSPP by two β‐cyclodextrin cavities were measured for both forms of the dimer, and molecular modeling confirms that both are flexible enough to tightly bind TSPP. The binding differences between the forms of dimer 4 allow the photocontrolled release and uptake of TSPP, which renders control of the ratio of complexed to free TSPP in solution possible.

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Section: Resultsmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Photocontrolled Release and Uptake of a Porphyrin Guest by Dithienylethene‐Tethered β‐Cyclodextrin Host Dimers

Mulder

Juković

Leeuwen

et al. 2004

Chemistry A European J

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“…In addition, some chromophores have a very specific absorption band, which makes their photoexcitation very selective and allows for precise control of the system. Several light-responsive processes have been used to trigger molecular or supramolecular events, such as the cis-trans isomerization of azobenzene, [9][10][11][12][13][14][15][16][17] alkenes, [18][19][20] or overcrowded alkenes, [21][22][23] the closing/opening of diarylethenes, [24][25][26][27][28] the cleavage of coordination bonds, [29][30][31][32][33][34] or the linkage isomerization of transitionmetal complexes. [35][36][37] Over the years, light-responsive supramolecular interactions, such as that between trans-azobenzene and cyclodextrin, have led to a particularly large number of applications in nanotechnologies, chemical biology, and drug delivery.…”

mentioning

confidence: 99%

Ruthenium Polypyridyl Complexes Hopping at Anionic Lipid Bilayers through a Supramolecular Bond Sensitive to Visible Light

Bahreman¹,

Limburg²,

Siegler³

et al. 2012

Chemistry A European J

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The new ruthenium complex [Ru(terpy)(dcbpy)(Hmte)](PF(6))(2) ([2](PF(6))(2); dcbpy=6,6'-dichloro-2,2'-bipyridine, terpy=2,2';6',2"-terpyridine, Hmte=2-(methylthio)ethanol) was synthesized. In the crystal structure, this complex is highly distorted, revealing steric congestion between dcbpy and Hmte. In water, [2](2+) forms spontaneously by reacting Hmte and the aqua complex [Ru(terpy)(dcbpy)(OH(2))](2+) ([1](2+)), with a second-order rate constant of 0.025 s(-1) M(-1) at 25 °C. In the dark, the Ru-S bond of [2](2+) is thermally unstable and partially hydrolyzes; in fact, [1](2+) and [2](2+) are in an equilibrium characterized by an equilibrium constant K of 151 M(-1). When exposed to visible light, the Ru-S bond is selectively broken to release [1](2+), that is, the equilibrium is shifted by visible-light irradiation. The light-induced equilibrium shifts were repeated four times without major signs of degradation; the Ru-S coordination bond in [2](2+) can be described as a robust, light-sensitive, supramolecular bond in water. To demonstrate the potential of this system in supramolecular chemistry, a new thioether-cholesterol conjugate (4), which inserts into lipid bilayers through its cholesterol moiety and coordinates to ruthenium through its sulfur atom, was synthesized. Thioether-functionalized, anionic, dimyristoylphosphatidylglycerol (DMPG), lipid vesicles, to which aqua complex [1](2+) efficiently coordinates, were prepared. Upon exposure of the Ru-decorated vesicles to visible light, the Ru-S bond is selectively broken, thus releasing [1](2+) that stays at the water-bilayer interface. When the light is switched off, the metal complex spontaneously coordinates back to the membrane-embedded thioether ligands without a need to heat the system. This process was repeated four times at 35 °C, thus achieving light-triggered hopping of the metal complex at the water-bilayer interface.

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“…This is desirable, for example, for targeted drug delivery with macrocycles. Traditionally, the cis-trans isomerisation of azobenzenes, 1 the ring opening/ closing of diarylethene switches, 2 or the reversible intramolecular [4+4] photocycloaddition of anthracenes 3,4 have been used to trigger a photochemical response of host macrocycles. In other case studies, it has been the photochromic guest itself which is complexed only in one isomeric form.…”

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confidence: 99%