Highly constrained guests in complexes of p-tert-butylcalix[6]arene dianion: Pentane-1,5-diammonium and choline

Lazzarotto, Márcio; Ferreira, Creusa Iara; Castellano, Eduardo E.; Veglia, Alicia V.

doi:10.1016/j.molstruc.2014.03.004

Cited by 3 publications

(2 citation statements)

References 23 publications

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“…8 Equilibrium of the inclusion of tetramehyl ammonium; plot of absorbance at 310 nm with the molar ratio n TMAOH /n p-t-bucalix [6]arene in ethanol in the box [19], where the cation is deeply immersed in the cavity, as well for choline complex [20]. Competitive experiments of crystallization of dianion of 3 showed selectivity for tetramethylammonium salts in presence of alkaline cations.…”

Section: Para-tert-butylcalix[6]arene In Ethanolmentioning

confidence: 99%

Counter-ion and solvent effects on the acidity of calix[4]arene and para-tert-butylcalix[6]arene

Miñambres

Jaques

Veglia

et al. 2014

J Incl Phenom Macrocycl Chem

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Spectrophotometric titrations of calix[4]arene and p-tert-butylcalix[6]arene with LiOH, NaOH, KOH, tetramethylmmonium and tetrabutylammonium hydroxides as bases were carried in ethanol 95 % and acetonitrile. The dependence of pK a of the first deprotonation of calix[4]-arene with the nature of the cation was only modest in ethanol 95 %, spanning from 8.53 pK a unit for NaOH until 9.00 for LiOH, whereas in acetonitrile the proton transfer is quantitative. The first deprotonation of p-t-butylcalix[6]arene in both solvents is quantitative and the extension of the second deprotonation is very dependent of the nature of the cation in ethanol and acetonitrile. Tetramethylammonium hydroxide was the strongest base for both solvents, and both deprotonations proceed quantitatively and concomitantly in ethanol, followed by potassium hydroxide, and the weakest base was tetrabutylammonium hydroxide. This behavior indicates that the ability to form N ? -C-H-p and K ? -p interactions plays an important role to stabilize the mono and dianion calixarene. Lithium and sodium exhibit non-usual acid-base behavior in acetonitrile, attributed to aggregation of the species.

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Section: Para-tert-butylcalix[6]arene In Ethanolmentioning

confidence: 99%

Counter-ion and solvent effects on the acidity of calix[4]arene and para-tert-butylcalix[6]arene

Miñambres

Jaques

Veglia

et al. 2014

J Incl Phenom Macrocycl Chem

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“…1 The semi-rigid structures and the p-electron rich cavities provide a suitable platform for the study of host-guest complexation. 2 The cone and alternated architectures afford the design of receptors for molecules and ions which have been applied in molecular recognition, 3 sensors, 4 thin films, [5][6][7] and drug-delivery systems 8 and as templates for forming supramolecular aggregates. 9 In a previous study, 10 experimental and theoretical results showed that para-tert-butylcalix [6]arene may form dimeric structures, which accumulate as large aggregates at high pressures at the water/air interface.…”

Section: Introductionmentioning

confidence: 99%

An experimental and theoretical study of the aggregate structure of calix[6]arenes in Langmuir films at the water/air interface

Lara

Wrobel

Lazzarotto

et al. 2016

Phys. Chem. Chem. Phys.

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In this paper, the aggregate formation of para-tert-butylcalix[6]arene molecules (Calix6) in dimeric structures was investigated at the water/air interface using experimental and theoretical studies. A specific orientation for such Calix6 molecules was observed with an average area of 133 Å(2), which corresponds to a flat-on orientation with the OH groups parallel to the interface. By varying the pressure on the Calix6 monolayer, the molecules tend to organize at the water/air interface and subsequently, at higher pressures, aggregates were formed atop the monolayer as cluster structures. Morphological characterization by the Brewster Angle Microscopy technique showed the formation of larger domains at lower pressures. Based on such experimental evidence, molecular dynamics (MD) simulations were performed to investigate possible dimeric structures for aggregated Calix6 molecules, which are localized at the water/air interface, where one molecule remains in the water phase and the other remains in the air phase. By increasing surface pressure, experimental and theoretical results corroborate the intermolecular interactions among Calix6 molecules. These results are relevant because a dimeric structure has a molecular cavity, which is a candidate for host-guest chemistry, an ion receptor or a drug-delivery system.

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Influence of the para‐Substituent in Lanthanoid Complexes of Bis‐Tetrazole‐Substituted Calix[4]arenes

et al. 2019

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5,11,17,arene has been reported to form remarkable Ln19 and Ln12 elongated clusters, upon addition of aqueous ammonium carboxylates. The impact of the para substituent on lanthanoid cluster formation has been studied by synthesising two new bis-tetrazole calixarenes, with p-H, and p-allyl substituents. Solution phase dynamic light scattering measurements of the reaction mixtures indicated that clusters are not formed with the p-H and p-allyl derivatives, in contrast with the behaviour of the tert-butyl analogue. Lanthanoid com- [a]

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Highly constrained guests in complexes of p-tert-butylcalix[6]arene dianion: Pentane-1,5-diammonium and choline

Cited by 3 publications

References 23 publications

Counter-ion and solvent effects on the acidity of calix[4]arene and para-tert-butylcalix[6]arene

Counter-ion and solvent effects on the acidity of calix[4]arene and para-tert-butylcalix[6]arene

An experimental and theoretical study of the aggregate structure of calix[6]arenes in Langmuir films at the water/air interface

Influence of the para‐Substituent in Lanthanoid Complexes of Bis‐Tetrazole‐Substituted Calix[4]arenes

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