A study of Dianin's inclusion compound NMR and energy calculations

Zaborowski, Eduardo; Vega, Shimon

doi:10.1080/00268979300100471

Cited by 10 publications

(9 citation statements)

References 28 publications

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“…13 C CP-MAS NMR showed the in¯uence of the cage distortions on the isotropic chemical shifts of the host carbons. These distortions are strongest for the methyl groups that dominate the shape of the potential of the cage [10], as predicted by our MM simulations. These e ects are temperature dependent, and are in accordance with the temperature dependent librations and average positions of the p-xylene guests as seen by deuteron NMR.…”

mentioning

confidence: 61%

“…observed [10] by 2 H-NMR of powder samples that, at temperatures as low as 120 K, p-xylene molecules in Dianin's compound undergo 180 ë¯i ps about their long molecular axis, and that there exists further motional averaging of the deuteron quadrupolar tensors at ambient temperatures and above. They calculated the potential energy function which is probed by various guest molecules, including p-xylene, in the cages of their Dianin's inclusion compounds.…”

Section: Introductionmentioning

confidence: 90%

“…Two hexamers with a guest molecule trapped in between have 498 atoms, and a cube with 3´3´3 cages would have almost 7000 atoms! Our previous calculations [10] were made considering the smallest possible unit of the Dianin's inclusion compound, i.e., one cage. This includes one guest molecule (in the case of p-xylene) and the six closest host molecules, three of them belonging to an upper hexamer and three to a lower one (as a guide, see ® gure 2).…”

Section: Molecular Mechanics Simulationsmentioning

confidence: 99%

“…Two types of three symmetry related (C 3 ) sites were found. Type I sites ® tted exactly the time-average equilibrium orientations proposed in [10], while type II sites were in total contradiction with the potential of a rigid cage. The dynamics of the type I and type II guests were found to be essentially the same: 180 ë jumps and, in addition, uniaxial librations about the long axes with amplitudes increasing with temperature and reaching a libration angle of 20 ë at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Solid state NMR and molecular modelling of the p-xylene adduct of Dianin's compound

Zaborowski¹,

Vega²,

Speier

et al. 1997

Molecular Physics

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The p-xylene adduct of Dianin's compound was studied by solid state NMR and molecular modelling. Molecular potential calculations were performed considering a p-xylene guest molecule in a single host cage. These calculations confirmed the existence of six different possible orientations of the guest molecules in the cage. The orientations correspond to two types of guests, which are not related by any symmetry, each consisting of three C3 symmetry related sites. The two types induce significant distortions to the local structure of the host crystal cage, and these are most pronounced at the bottle-neck of the cage. In the calculations no diffusion paths were found that transferred guest molecules of one type to the other. X-Ray studies confirmed that the dimensions of the p-xylene/Dianin's cages are essentially equal to those reported previously. In our case, the R3 space groups failed to describe the X-ray diffraction data accurately. Single crystal 2H-NMR of the p-xylene/Dianin's compound, specifically deuterated in the hydroxyl groups of the cage, provided detailed information on the distortions of the hexagons of hydroxyl groups interconnecting two cages. The hexagon distortions were correlated to the orientation of the guest molecules. 13C CP-MAS NMR confirmed that the methyl groups of the host, in the middle of the cage, are influenced strongly by the inclusion of the p-xylene molecules. Based on the experimental observations, a model describing the distortions in the crystal is proposed

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mentioning

confidence: 61%

Section: Introductionmentioning

confidence: 90%

Section: Molecular Mechanics Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solid state NMR and molecular modelling of the p-xylene adduct of Dianin's compound

Zaborowski¹,

Vega²,

Speier

et al. 1997

Molecular Physics

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“…have recently studied the potential energy function which is sensed by various guest molecules including p-xylene in the cavities of Dianin's compound [2], henceforth referred to as I. From these calculations they derived, among other things, the time-average orientations which the p-xylene guests should take in the cages of Dianin's compound.…”

Section: Introductionmentioning

confidence: 99%

The sites and dynamics of p-xylene guest molecules in Dianin’s inclusion compound; a deuteron NMR study

et al. 1995

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Abstraet. Single crystals of Dianin's inclusion eompound with methyl and ¡ deuterated p-xylene guest molecules were grown and studied by FT deuteron NMR. The spectra from the deuterated methyl groups reveal that these groups reo¡ rapidly down to 12 K; thereat~er they enter hato the tunneling regime. The rings of the p-xylene guests become motionless when T reaches 110 K. By measu¡ the orientation dependence of the quadrupole splittings, determining from these data the quadrupole eoupling tensors of the ring deuterons and relating these tensors to the C-D bond directions we infer the sites of the p-xylene guests in the cages of Dianin's inclusion compound. We final two sets of independent sites. Each contains three C 3 related individual sites. In each set the population of one of the sites is strongly depleted. The only large-angle molecular motions are 180 ~ rotational jumps about the long molecular axes. From measurements of T~ we conclude that these jumps are thermally activated, ro = 5.10 -~4 s, AE = 20 kJ/mol. Additional motions are rapid librations, also about the iong molecular axes. Their amplitude increases with increasing temperature, at 300 K it reaches 20 o. With 2D-exchange speetra we demonstrate that a p-xylene guest cannot change its site on a timescale of 100 ras anda tempe¡ expe¡ suggests that this is true on a timescale of several days even at T = 371 K.

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Synthesis and Structure of the Inclusion Compound COF300‐ALA

et al. 2023

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Comprehensive SummaryFinding a new multimolecular lattice inclusion host is still challenging. We report the synthesis and the crystal structure of the first example of an inclusion compound COF300‐ALA by using three‐dimensional covalent organic frameworks (3D‐COFs) as the multimolecular host lattice. The guest‐host dynamics upon inclusion and exclusion of the gust molecule are uncovered in a 3D covalent organic framework.This article is protected by copyright. All rights reserved.

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A study of Dianin's inclusion compound NMR and energy calculations

Cited by 10 publications

References 28 publications

Solid state NMR and molecular modelling of the p-xylene adduct of Dianin's compound

Solid state NMR and molecular modelling of the p-xylene adduct of Dianin's compound

The sites and dynamics of p-xylene guest molecules in Dianin’s inclusion compound; a deuteron NMR study

Synthesis and Structure of the Inclusion Compound COF300‐ALA

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