Kinetics Inside, Outside and Through Cucurbiturils

Masson, Éric; Raeisi, Mersad; Kotturi, Kondalarao

doi:10.1002/ijch.201700120

Cited by 36 publications

(37 citation statements)

References 143 publications

(379 reference statements)

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“…[43] As can be seen in the early stage of the titration (Figure 3), the threading of a non-symmetrical viologen-based axle through CB [7] also results in the splitting of the Hi protons, observed as two partially overlapped doublets (pseudo triplet at 5.80 ppm) in the spectrum of the inclusion complex. The effect of the viologen-based guests on the CB [7] hosts is further revealed on the spectrum recorded at low concentration of 1Zn 8+ (0.1 mM) in the presence of 8 equivalents of CB [7] (top spectrum in Figure 3 A similar investigation has been carried out with the less soluble CB [8] host, featuring a wider inner cavity but still capable of forming 1/1 inclusion complexes with viologens derivatives [34,44,45]. The stoichiometry and structure of the assembly is also deduced from the titration data depicted in Figure 4.…”

Section: Threading Of the Cb[7] Or Cb[8] Rings On 1m 8+mentioning

confidence: 90%

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Chowdhury

Nassar

Guy

et al. 2019

Electrochimica Acta

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The present paper reports on the formation and on the electrochemical/spectroscopic characterization of inclusion complexes formed in aqueous media between cucurbit[7 or 8]urils cavitands (CB[7], CB[8]) and a rigid four-pointed star-shaped viologen-appended porphyrin tecton. The formation of discrete 4:1 pseudo-rotaxane-like caviplexes, involving threading of CB[n] rings on the rigid viologen-based star's branches has been demonstrated by nuclear magnetic resonance and mass spectrometry measurements. Then, the photo-and redoxtriggered formation of 2D supramolecular assemblies involving CB[8]s and the four electron reduced tectons as key building elements, has been established on the ground of in-depth electrochemical and spectroscopic analyses supported by quantum calculations. The CB[8]promoted intermolecular -dimerization of the viologen cation radicals introduced at the meso positions of the porphyrin plateform has been brought to light through the diagnostic signatures of the 1:2 host-guest ternary caviplexes formed between viologen and CB[8] and by spectroscopic data collected after electrochemical, chemical or photochemical reduction of the viologen-based tectons. The CB[8] hosts not only proved useful to promote the redox-triggeredformation of supramolecular assemblies, it was also found to prevent the chemical reduction of the porphyrin ring in aqueous media and its subsequent conversion into phlorin products.

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Section: Threading Of the Cb[7] Or Cb[8] Rings On 1m 8+mentioning

confidence: 90%

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Chowdhury

Nassar

Guy

et al. 2019

Electrochimica Acta

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“…From a thermodynamic point of view, the exceptionally high affinity of CB[ n ]s for positively charged organic guests in water is attributed to a combination of factors including the desolvation of the guest, the ejection of ‘high energy’ water molecules trapped inside CB[ n ]s prior to encapsulation, and ion–dipole interactions between the carbonyl functions at the cavity portal and any positively charged parts of the guest. In most cases only one guest can be fitted within the cavity of the smallest CB[ n ] ( n = 5, 6, 7) while the larger cavity of CB[8] can potentially accommodate two or even three guests …”

Section: Soluble Supramolecular Assembliesmentioning

confidence: 99%

“…In most cases only one guest can be fitted within the cavity of the smallest CB[n] (n = 5, 6, 7) while the larger cavity of CB [8] can potentially accommodate two or even three guests. [30][31][32][33][34][35] Most efforts in the field of supramolecular chemistry have focused on CB [8], on account of its ability to accommodate two -conjugated guests tightly interacting inside the barrel-shaped cavity in the form of cofacial charge transfer complexes. 36 The opportunities are more limited for the smallest analogs CB [5], CB [6] and CB [7], whose inner cavities only allow hosting single guests.…”

Section: Soluble Supramolecular Assembliesmentioning

confidence: 99%

Dynamic supramolecular polymers built from cucurbit[n]urils and viologens

Correia

Chowdhury

Ramos

et al. 2018

Polymer International

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This review article focuses on supramolecular assemblies involving cucurbit[n]uril‐based containers and viologen guests as key building elements. Cucurbit[n]urils (CB[n], n = 5–8,10) are fascinating hosts forming a wide range of inclusion complexes (caviplexes) with 4,4′‐bipyridinium salts, known as viologens, either as discrete 1:1 inclusion compounds with CB[7] or as ternary inclusion compounds involving two hosts or two guests (2:1 with CB[7] and 1:2 or 1:1:1 with CB[8]). This property is currently being actively exploited to design and prepare self‐assembled dynamic stimuli‐responsive supramolecular polymers including gels, vesicles, films and organized arrays of polymeric microspheres or nanoparticles. This review highlights the main benefits of such polymers and gives an overview of the achievements and progress made in this field over the past decades. © 2018 Society of Chemical Industry

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“…As far as emissions are concerned, blueshifts, reduced Stokes shifts and fluorescence enhancements are frequently observed upon guest encapsulation by CB[ n ], as the polarity and polarizability of the macrocycles are low, and encapsulation limits nonradiative decay from the excited state through solvent relaxation . To the best of our knowledge, we report here for the first time the effect of CB[ n ] encapsulation on the phosphorescence of a chromophore.…”

Section: Resultsmentioning

confidence: 95%

Directional Self‐Sorting with Cucurbit[8]uril Controlled by Allosteric π–π and Metal–Metal Interactions

Kotturi

Masson

2018

Chemistry A European J

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To maximize Coulombic interactions, cucurbit[8]uril (CB[8]) typically forms ternary complexes that distribute the positive charges of the pair of guests (if any) over both carbonylated portals of the macrocycle. We present here the first exception to this recognition pattern. Platinum(II) acetylides flanked by 4'-substituted terpyridyl ligands (tpy) form 2:1 complexes with CB[8] in an exclusively stacked head-to-head orientation in a water/acetonitrile mixture. The host encapsulates the pair of tpy substituents, and both positive Pt centers sit on top of each other at the same CB[8] rim, leaving the other rim free of any interaction with the guests. This dramatic charge imbalance between the CB[8] rims would be electrostatically penalizing, were it not for allosteric π-π interactions between the stacked tpy ligands, and possible metal-metal interactions between both Pt centers. When both tpy and acetylides are substituted with aryl units, the metal-ligand complexes form 2:2 assemblies with CB[8] in aqueous medium, and the directionality of the assembly (head-to-head or head-to-tail) can be controlled, both kinetically and thermodynamically.

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Kinetics Inside, Outside and Through Cucurbiturils

Cited by 36 publications

References 143 publications

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Dynamic supramolecular polymers built from cucurbit[n]urils and viologens

Directional Self‐Sorting with Cucurbit[8]uril Controlled by Allosteric π–π and Metal–Metal Interactions

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