Molecular Assembly Structure of CCl<sub>4</sub> in Graphitic Nanospaces

Iiyama, Taku; Nishikawa, Keiko; Suzuki, Toshio; Otowa, Toshiro; Hijiriyama, M.; Nojima, Yuki; Kaneko, Katsumi

doi:10.1021/jp962408h

Cited by 68 publications

(75 citation statements)

References 33 publications

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“…The temperature dependence of the ERDFs of water molecules in A25 micropores at φ = 0.85 are shown in Figure 7, which also shows the ERDFs of bulk water at 298 K. Details of the ERDF derivation were provided in our previous work. 16 The ERDF of bulk water shows three peaks at 0.30, 0.42, and 0.70 nm, corresponding to the first, second, and third nearest neighbours of water molecules, respectively. This indicates that water does not possess long-range order longer than 0.8 nm.…”

Section: Radial Distribution Function Of Confined Watermentioning

confidence: 99%

Negative thermal expansion of water in hydrophobic nanospaces

Futamura

Iiyama

Hamasaki

et al. 2012

Phys. Chem. Chem. Phys.

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The density and intermolecular structure of water in carbon micropores (w = 1.36 nm) are investigated by small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) measurements between 20 K and 298 K. The SAXS results suggest that the density of the water in the micropores increased with increasing temperature over a wide temperature range (20-277 K). The density changed by 10%, which is comparable to the density change of 7% between bulk ice (I c ) at 20 K and water at 277 K. The results of XRD at low temperatures (less than 200 K) show that the water forms the cubic ice (I c ) structure, although its peak shape and radial distribution functions changed continuously to those of a liquid-like structure with increasing temperature. The SAXS and XRD results both showed that the water in the hydrophobic nanospaces had no phase transition point. The continuous structural change from ice I c to liquid with increasing temperature suggests that water shows negative thermal expansion over a wide temperature range in hydrophobic nanospaces. The combination of XRD and SAXS measurements makes it possible to describe confined systems in nanospaces with intermolecular structure and density of adsorbed molecular assemblies.3

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Section: Radial Distribution Function Of Confined Watermentioning

confidence: 99%

Negative thermal expansion of water in hydrophobic nanospaces

Futamura

Iiyama

Hamasaki

et al. 2012

Phys. Chem. Chem. Phys.

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“…The XRD profiles were corrected by an appropriate method, and the scattering intensity from adsorbed CHCl 3 assembly was extracted from the XRD profiles corrected by subtraction the diffraction data of carbon itself. The experimental setup and extracting methods were already published in the previous article (Iiyama et al, 1997b).…”

Section: Methodsmentioning

confidence: 99%

“…micropore width in the range of 1 to 2 molecular diameters (Iiyama et al, 1997b;Suzuki et al, 1999). In the CHCl 3 -W10 system, the adsorbed molecules form ordered structure in which the dipole stands in vertical to the carbon surface and an anti-parallel side-by-side order.…”

mentioning

confidence: 99%

Structural Study of CHCl3 Molecular Assemblies in Micropores Using X-ray Techniques

Iiyama

Kobayashi

Matsumoto³

et al. 2005

Adsorption

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Abstract. The X-ray diffraction from CHCl 3 molecules adsorbed in slit-shaped micropores of activated carbon fibers were measured at 298 K. The pore effect on structure of molecular assemblies in the graphitic micropores was examined. The peak positions due to the first nearest neighbor CHCl 3 in the electron radial distribution function of adsorbed phase agreed with those of bulk liquid, although their peak intensities were different. In narrow pores (pore width w = 1.1 nm), the peak intensities due to the first nearest molecule are stronger than the bulk liquid, because a peak due to the correlation between carbon walls and CHCl 3 molecules was overlapped. In the wider pores of ACF W10 (w = 1.3 nm) having high CHCl 3 removal efficiency from tap water, the intensity of the peak of r = 0.4 nm is the strongest. It suggests that CHCl 3 molecules in the 1.3 nm micropores should be orientated for a Cl atom to meet with a carbon atom in wall surfaces. These results demonstrate that the structure of a polar molecule such as CHCl 3 will sensitively be subject to micropore effects. Keywords: CHCl 3 (chloroform), microporous carbon, XRD, radial distribution function, dipole IntroductionThe behavior of molecules confined in small space has attracted much attention. These molecules show the special phenomena such as unique phase transition and ordered structure formation (Iiyama et al., 1997a). One of origins of these phenomena is the fact that the adsorbed phase is constituted by small number of molecules. The analysis method for adsorbed phases in the micropore in molecular level is limited, because the micropore space is surrounded by the solid. Since X-ray can penetrate various materials, we can detect directly the structural information on adsorbed phase itself in micropore with the X-ray techniques. The information of intermolecular structure among adsorbed molecules can be obtained by in situ X-ray diffraction (XRD) measurement. In previous studies, we showed by using this method that water molecules form a solid-like structure in the carbon micropore even at room temperature (Iiyama et al., 1995). On the other hand, small angle X-ray scattering (SAXS) can provide the information about shape and size of adsorbed molecular assemblies (Iiyama et al., 2000). The density fluctuation of adsorption systems changes with adsorption which molecules fill empty pores. We reported that the density fluctuation and correlation length from SAXS can directly translate to the size of both

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“…20 Here a plastic crystal is defined as a special solid phase having long-range positional order for the center of the molecules, but only shortrange orientational order. GCMC simulation and in situ X-ray diffraction studies have shown that the plastic crystal phase is stable in slit-shaped pores of ACF whose width is smaller than 1 nm at 303 K. 21 This indicates the transition temperature of the plastic crystal in the micropores is shifted by 53 K at least. Thus, nanoconfinement induces a marked enhancement of the collective interaction between molecules, stabilizing the low-temperature phase.…”

Section: In-pore Phase Anomalymentioning

confidence: 99%

Collective Interactions of Molecules with an Interfacial Solid

2012

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Confinement of molecules in nanoscale pores of an interfacial solid such as single wall carbon nanotubes of which all component carbon atoms are exposed to the interface with gas phase induces collective phenomena; the confinement effect is interpreted by the interaction potential theory. The nanoconfinement effect gives rise to in-pore phase anomalies for NO, H 2 O, CCl 4 , superhigh-pressure effect, hydrophobic to hydrophilic transformation for carbon, and a marked quantum molecular sieving. The confinement of KI in the nanotube space below 0.1 MPa produces high-pressure-phase KI above 1.9 GPa. Water molecules gain hydrophilicity with cluster formation in order to accommodate in the hydrophobic carbon spaces. The subnanometer quantum fluctuation for H 2 and D 2 gives rise to a marked quantum molecular sieving effect in nanoscale pores. The Cubased porous coordination polymer crystals can detect the surrounding stimuli such as CO 2 pressure change to vary the crystal lattice, accompanying gate adsorption.

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Molecular Assembly Structure of CCl₄ in Graphitic Nanospaces

Cited by 68 publications

References 33 publications

Negative thermal expansion of water in hydrophobic nanospaces

Negative thermal expansion of water in hydrophobic nanospaces

Structural Study of CHCl3 Molecular Assemblies in Micropores Using X-ray Techniques

Collective Interactions of Molecules with an Interfacial Solid

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Molecular Assembly Structure of CCl4 in Graphitic Nanospaces

Cited by 68 publications

References 33 publications

Negative thermal expansion of water in hydrophobic nanospaces

Negative thermal expansion of water in hydrophobic nanospaces

Structural Study of CHCl3 Molecular Assemblies in Micropores Using X-ray Techniques

Collective Interactions of Molecules with an Interfacial Solid

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Molecular Assembly Structure of CCl₄ in Graphitic Nanospaces