Dynamics of some n-Alkanes Adsorbed in the Micropore of (±)-[Co(en)3]Cl3 as Studied by 2H NMR

Nagaoka, Naomi; Ueda, Takahiro; Nakamura, N.

doi:10.1515/zna-2002-6-726

Cited by 10 publications

(2 citation statements)

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“…48 Furthermore, we recently reported the ability of the anhydrous complex to adsorb linear aliphatic hydrocarbons; the dynamics of the adsorbed n-alkanes were investigated by 2 H NMR. 49 Thus, the previous studies indirectly imply the existence of a nanopore that can accommodate water and/or other molecules, but detailed information about the pore structure, especially from the microscopic point of view is unavailable.…”

Section: Introductionmentioning

confidence: 99%

High-Pressure ¹²⁹Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)₃]Cl₃

et al. 2002

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High-pressure 129 Xe NMR measurements were carried out on dehydrated (()-[Co(en) 3 ]Cl 3 to investigate the pore size as well as the local structure about the confined xenon atoms. At xenon gas pressures of 0.3 MPa, the xenon chemical shift was orientation dependent, exhibiting an axially symmetric powder pattern with δ 11 ) 280 ppm and δ 22 ) δ 33 ) 180 ppm. Proton to 129 Xe cross-polarization (CP) experiments selectively enhanced the portion of the powder pattern corresponding to δ 22 ) δ 33 ) δ ⊥ , confirming that the unique component of the chemical shift tensor, δ 11 ) δ | , lies along the pore axis. The isotropic chemical shift δ iso at the zero pressure limit was found to be 212 ppm, and suggested a pore diameter of approximately 0.47 nm. This agrees well with the diameter of 0.44 nm estimated from the crystal structure. On increasing the pressure to 6.5 MPa, δ ⊥ increased from 180 to 220 ppm, whereas δ | was found to be almost independent of pressure. The increase in δ ⊥ with pressure is attributed to Xe-Xe interactions. The paramagnetic shift in the xenon chemical tensor component perpendicular to the nanochannels with increasing pressure is in accord with the recent theoretical predictions of Jameson and de Dios (J.

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Section: Introductionmentioning

confidence: 99%

High-Pressure ¹²⁹Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)₃]Cl₃

et al. 2002

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“…The sorption and desorption processes of the hydration water are characterized macroscopically by the capillary condensation and so the water is thought to have a “zeolitic” property . Very recently, we found that the water accommodated in the pore of this substance can be substituted for some organic chain molecules such as n -alkanes, n -alcohols, n -alkylamines, and acetonitrile with no destruction of the crystal lattice . We also carried out 129 Xe NMR measurements on this compound to examine the pore structure.…”

Section: Introductionmentioning

confidence: 99%

H MAS NMR Study of Local Structure and Dynamics of Water Molecule in (±)-[Co(en)₃]Cl₃·nD₂O

Ueda

Nakamura

2003

J. Phys. Chem. B

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Dependence of the local structure and dynamic behavior of hydration water in (±)-[Co(en)3]Cl3·nD2O crystal (0 ≤ n ≤ 4) on the dehydration process was studied by means of 1H magic-angle sample spinning (MAS) NMR technique. The line shape in the 1H MAS NMR spectrum depends strongly on the water content (n). For n < 1.5, the spectrum consists mainly of two peaks whose relative intensities change with n, suggesting that the hydration water forms two different types of domainlike structures at room temperature. In addition, the full width at half-maximum of each component of the doublet was less than 1 ppm at room temperature, implying that the water moves rapidly enough to reduce the intermolecular 1H−1H dipole interaction. On cooling, the resonance line broadens and its line width exceeds 10 ppm below 200 K where the components of the doublets cannot be discerned. This aspect suggests that the water molecule undergoes slower motion than the MAS rate (5.0−7.0 kHz). The temperature dependence of the line width was analyzed by assuming the Davidson−Cole's spectral density. The activation energy (E a) for the molecular motion of the water depends drastically on the water content: E a assumes the constant value of 24 kJ mol-1 for n ≤ 2.1, but it decreases continuously for n > 2.1 and reaches 18 kJ mol-1 at n = 4. This finding suggests that the molecular motion of hydration water in the pore, which averages out the dipolar interaction between a trace amount of HDO and the protons on the pore wall, changes from whole molecular translational jump to proton migration through hydrogen bond accompanied by molecular reorientation.

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Gas‐Conforming Transformability of an Ionic Single‐Crystal Host Consisting of Discrete Charged Components

2008

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Tris(ethylenediamine)cobalt(III) chloride, [Co III (en) 3 ]Cl 3 (en = ethylenediamine), is one of the most fundamental compounds of coordination chemistry. Although the wellknown ethylenediamine complexes may be regarded as well studied, research that considers their gas-adsorbent ability has not been reported. The racemic hydrated crystal of (AE )-[Co(en) 3 ]Cl 3 (1) includes H 2 O molecules within the onedimensional channels (see Figure 1).[1] Although the "zeolitic" behavior of 1 as a hydrate and dehydrate was reported in 1959,[2] the gas-adsorption ability of dried crystals of 1 was recently euphemistically indicated in 2002 and 2003 by a solidstate NMR spectroscopic study of n-alkanes under saturated vapor as well as of loaded Xe gas at high pressure.[3] Currently, porous materials based on metal complexes are very attractive research targets owing to their designable structure, unusual flexibilities, and projected tunable functions. [4] Dynamic porosity has been given much attention for the function of dynamic guest inclusion, [4][5][6] which can control guest reactivity and stability. [7] In the context of host dimensionality and binding forces for the component skeletons, currently the most actively investigated materials generally consist of polymeric skeletons with the assistance of van der Waals interpolymer interactions. Such structures should be well restricted in their transformability regarding the direction and range of motion by how the 3D architecture is constructed. Thus, an ionic crystal consisting of charged spherical components can be considered to possess extremely unrestricted transformability, which is regulated mostly by the minimization of the ionic-crystal energy under the various gas-adsorbing states. In this case, the Coulombic potential is rather "loose" in terms of binding interaction, which is generated in isotropic radial directions over a long distance proportional to r À1 (r = intermolecular distance), whereas that of van der Waals interactions is proportional to r À6 . Thus, there is a possibility that the ionic crystal can transform its crystal structure to sensitively adapt to the various adsorbedguest properties even by weak physisorption. Because crystal 1 seems to satisfy these requirements for the target-flexible ionic porosity, we focus on the gas adsorbency of ionic crystal 1. The purely van der Waals molecular crystal host is known for the cyclotriphosphazene inclusion compound. [8] Well-formed hydrated single crystals of 1 ([Co III (en) 3 ]Cl 3 ·4 H 2 O) were obtained as hexagonal rods by recrystallization from water. The structure has 1D channels running along the rod axis perpendicular to the hexagonal (001) plane, forming a channel crystal with 1D penetration pores (Figure 2). Single-crystal X-ray diffraction analysis demonstrated the 1D channel structure of 1 including a 1D water chain with the infinite connectivity of a trigonalbipyramidal periodic unit (Figure 3 a). After vacuum drying at 60 8C, single-crystal X-ray diffraction analysis can be perform...

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Dynamics of some n-Alkanes Adsorbed in the Micropore of (±)-[Co(en)₃]Cl₃ as Studied by ²H NMR

Cited by 10 publications

References 7 publications

High-Pressure ¹²⁹Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)₃]Cl₃

High-Pressure ¹²⁹Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)₃]Cl₃

H MAS NMR Study of Local Structure and Dynamics of Water Molecule in (±)-[Co(en)₃]Cl₃·nD₂O

Gas‐Conforming Transformability of an Ionic Single‐Crystal Host Consisting of Discrete Charged Components

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Dynamics of some n-Alkanes Adsorbed in the Micropore of (±)-[Co(en)3]Cl3 as Studied by 2H NMR

Cited by 10 publications

References 7 publications

High-Pressure 129Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)3]Cl3

High-Pressure 129Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)3]Cl3

H MAS NMR Study of Local Structure and Dynamics of Water Molecule in (±)-[Co(en)3]Cl3·nD2O

Gas‐Conforming Transformability of an Ionic Single‐Crystal Host Consisting of Discrete Charged Components

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Dynamics of some n-Alkanes Adsorbed in the Micropore of (±)-[Co(en)₃]Cl₃ as Studied by ²H NMR

High-Pressure ¹²⁹Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)₃]Cl₃

High-Pressure ¹²⁹Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)₃]Cl₃

H MAS NMR Study of Local Structure and Dynamics of Water Molecule in (±)-[Co(en)₃]Cl₃·nD₂O