Order and Disorder inp-Dialkylbenzene–Urea Inclusion Compounds

Mayo, Sheridan C; Welberry, T. R.; Bown, Mark; Tarr, Allan W.

doi:10.1006/jssc.1998.7971

Cited by 6 publications

(7 citation statements)

References 21 publications

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“…Therefore, cooling might induce a better fit between a xenon atom and a sorption site and higher degree of guest ordering in the nanochannels. Phase transitions of this kind have been observed and studied in other inclusion compounds and may be induced by either temperature [64][65][66][67][68][69] or guest loading. 70,71 In a case of AI, the increase in entropy and decrease in q st might be a result of a stepwise increase in the channel diameter that takes place at a certain level of loading.…”

Section: Resultsmentioning

confidence: 97%

A New Approach to Characterizing Sorption in Materials with Flexible Micropores

et al. 2008

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Microporous dipeptides, also known as organic zeolites or biozeolites, as examples of small-pore peptide\ud nanotubes provide a convenient set of materials for developing a systematic approach based on 129Xe\ud NMR spectroscopy for the derivation of thermodynamic and molecular scale information on temperature\ud dependent pore filling. The sorption of xenon in the isolated 1D chiral nanochannels of eight microporous\ud dipeptides Ala-Val (AV), Val-Ala (VA), Leu-Ser (LS), Ala-Ile (AI), Val-Val (VV), Ile-Ala (IA), Ile-Val\ud (IV), Val-Ile (VI) (all LL isomers) was monitored in situ with continuous-flow 129Xe NMR spectroscopy\ud over a temperature range of 173-343 K. The materials all showed strongly anisotropic signals, with\ud isotropic chemical shift changing from 95 to 281 ppm depending on the dipeptide used and/or temperature.\ud The isosteric heats of sorption (qst) and entropy factors were determined from two independent models.\ud The sorption process was complicated by reversible phase transformations of some dipeptides and\ud irreversible changes due to aging of samples, both of which may be of considerable importance in\ud applications of soft materials. The interpretation of the line shapes and chemical shift anisotropy as a\ud function of temperature provided information on the structure of the xenon-cavity complex and made it\ud possible taking into account the helicity and flexibility of the nanochannels and the dynamics of xenon.\ud The approach illustrates a powerful way of analyzing pore space in soft microporous materials, yielding\ud a quantitative thermodynamic description of sorption and the characteristics of the pore space and sorption\ud events that occur on molecular-scale level during pore filling

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Section: Resultsmentioning

confidence: 97%

A New Approach to Characterizing Sorption in Materials with Flexible Micropores

et al. 2008

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“…In Figs. 1(a), (b) and (c), we show regions of the diffraction patterns of the aluminosilicate ceramic mullite (see Welberry & Withers, 1990;Butler & Welberry, 1994), a cubic stabilized zirconia (see Welberry et al, 1993Welberry et al, , 1995 and the inclusion compound didecylbenzene/urea (see Mayo et al, 1998), which all show such features. In Fig.…”

Section: Introductionmentioning

confidence: 85%

“…Urea acts as the host for a large number of different longchain molecular guests, not least of which are the n-alkanes, which have been studied over a period of many years. In a recent study, we surveyed a system in which a series of dialkylbenzene molecules were used as guests in order to investigate the ability of urea to accommodate the bulky benzene group, which is rather too large for the urea channels (see Mayo et al, 1998). Of these compounds, didecylbenzene (see Fig.…”

Section: Diffuse Circles In Didecylbenzene/urea Inclusion Compound 4mentioning

confidence: 99%

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Diffuse X-ray scattering and strain effects in disordered crystals

Welberry

2001

Acta Cryst Sect A

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It is shown in this paper that a feature that has been observed in the diffuse scattering patterns of a wide variety of different materials - a diffuse 'ring' or 'doughnut'-shaped region of scattering - can be understood in terms of a simple model that has been borrowed from the field of sol-gel science. In this, it is supposed that there is a balance between the local attractive forces that are trying to make a particular structure and a rather longer range repulsive force. In the present context, it is believed that this latter force has its origin in the strain that builds as the preferred local structure tries to fit into the average crystal lattice. Simple Monte Carlo (MC) computer simulations are described that demonstrate this principle for three example materials: cubic stabilized zirconia, the p-didecylbenzene/urea inclusion compound and the pure molecular compound 1,3-dibromo-2,5-diethyl-4,6-dimethylbenzene, C12H16Br2 (BEMB2).

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“…Urea inclusion compounds (UICs) with rod-shaped guests have been extensively studied and characterized. − These compounds typically have crystal structures that are hexagonal linear tunnels filled with guest species, incommensurate host and guest repeat distances, and orientationally disordered guest molecules, but with a standard urea repeat distance of 11 Å. , The incommensurate nature and orientational disorder have led to difficulty in characterization of numerous UICs resulting in a very small number of solved crystal structures (currently fewer than 50). The subset of reported UICs that exhibit commensurate structures − have guests with particular end groups: acetyl, amino, hydroxyl, and halo . Attempts to control morphology with a systematic method of crystal engineering have been successful in creating commensurate UICs but require molecules with well-defined properties and careful consideration of intermolecular interactions .…”

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confidence: 99%

Commensurate Urea Inclusion Crystals with the Guest (E,E)-1,4-Diiodo-1,3-Butadiene

Lashua

Smith

Hu³

et al. 2013

Crystal Growth & Design

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The urea inclusion compound (UIC) with (E,E)-1,4-diiodo-1,3-butadiene (DIBD) as a guest (DIB-D:UIC) has been prepared and crystallographically characterized at 90 and 298 K as a rare example of a commensurate, fully ordered UIC. The crystal shows nearly hexagonal channels in the monoclinic space group P2 1 /n. The DIBD guest molecules are arranged end-to-end with the nonbonding iodine atoms in van der Waals contact. The guest structure is compared with that for DIBD at 90 K and with computations for the periodic UIC and isolated DIBD molecule.

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Order and Disorder inp-Dialkylbenzene–Urea Inclusion Compounds

Cited by 6 publications

References 21 publications

A New Approach to Characterizing Sorption in Materials with Flexible Micropores

A New Approach to Characterizing Sorption in Materials with Flexible Micropores

Diffuse X-ray scattering and strain effects in disordered crystals

Commensurate Urea Inclusion Crystals with the Guest (E,E)-1,4-Diiodo-1,3-Butadiene

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