Observation of Electric-Field-Induced Liberation of Guest Molecules from Clathrate Hydrate

2021 ◽  
pp. 10410-10416
Author(s):  
Ziyue Li ◽  
Mengjie Lyu ◽  
Hannes Jónsson ◽  
Christoph Rose-Petruck
Keyword(s):  
Electric Field ◽  
Clathrate Hydrate ◽  
Guest Molecules

Clathrate and other solid phases in the tetrahydrofuran–water system: thermal conductivity and heat capacity under pressure

1982 ◽  
Vol 60 (7) ◽  
pp. 881-892 ◽  
Author(s):  
Russell G. Ross ◽  
Per Andersson
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Water System ◽  
Clathrate Hydrate ◽  
Transient Hot Wire ◽  
Guest Molecules ◽  
Hydrate Phase ◽  
Wire Method ◽  
Solid Phases ◽  
Thermal Conductivity Λ

Solid phases in the tetrahydrofuran–water (THF–H2O) system were investigated in the temperature range 100–260 K and at pressures up to 1.5 GPa. Thermal conductivity, λ, and heat capacity per unit volume, ρcp, were measured, using the transient hot-wire method. We made measurements on solid phases having nominal compositions THF•17H2O, THF•7•1H2O, and THF•4•6H2O, which we refer to as phases α, β, and γ, respectively. Phase α is known to be a structure II clathrate hydrate, and λ for this phase was found to be similar to other crystalline solids which are glass-like in relation to their thermal properties. Low-energy excitations are known to be relevant to the properties of glass-like solids, and, in the case of phase α, were probably rotational vibrations of the THF guest molecules. Phase β was similar, and we inferred that it was probably a structure I clathrate hydrate. Phase γ behaved nearly like a normal crystal phase at low temperatures, but λ became almost independent of temperature near melting. At 1.1 GPa and 130 K, we found evidence that phase α transformed, on pressurization, to a metastable modification which may be a new high-density form of clathrate hydrate. The astrophysical implications of our results were mentioned briefly.

Comments on the Infrared Spectra of SO2 Clathrate-hydrate Formed by Vapor Condensation

1971 ◽  
Vol 49 (24) ◽  
pp. 4114-4115 ◽  
Author(s):  
A. H. Hardin ◽  
K. B. Harvey
Keyword(s):  
Amorphous Phase ◽  
Infrared Spectra ◽  
Transformation Temperature ◽  
Vapor Condensation ◽  
Clathrate Hydrate ◽  
Hindered Rotation ◽  
Guest Molecules ◽  
Gaseous Mixtures

Gaseous mixtures having clathrate-hydrate stoichiometries were condensed at 83 °K into an amorphous phase. Infrared spectra were recorded at a series of temperatures up to 180 °K in order to determine the transformation temperature and the nature of the annealed phase. Bands associated with the H2O molecules began to shift position at 125 °K while those attributed to guest molecules decreased to null intensity. There was no evidence of a unique clathrate-hydrate H2O spectrum nor of free or hindered rotation of the guest molecules.

Stimulus-responsive adsorbent materials for CO2 capture and separation

2020 ◽  
Vol 8 (21) ◽  
pp. 10519-10533 ◽  
Author(s):  
Maohuai Wang ◽  
Sainan Zhou ◽  
Shoufu Cao ◽  
Zhaojie Wang ◽  
Siyuan Liu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Co2 Capture ◽  
Separation Performance ◽  
Guest Molecules ◽  
Stimulus Responsive ◽  
Adsorbent Materials

Stimulus-responsive adsorbent materials exhibit tunable CO2 capture and separation performance in response to pressure, temperature, light, electric field, magnetic field, guest molecules, pH, and redox.

scholarly journals Supramolecular Stark Effect in Host-Guest Complexes via Charge Density Analysis

2014 ◽  
Vol 70 (a1) ◽  
pp. C674-C674
Author(s):  
Sajesh Thomas ◽  
Rebecca Fuller ◽  
Alexandre Sobolev ◽  
Philip Schauer ◽  
Simon Grabowsky ◽  
...  
Keyword(s):  
Electric Field ◽  
Charge Density ◽  
Electric Fields ◽  
Active Sites ◽  
Stark Effect ◽  
Dipole Moments ◽  
Covalent Bonds ◽  
Guest Molecules ◽  
Density Mapping ◽  
Density Analysis

The effect of an electric field on the vibrational spectra, the Vibrational Stark Effect (VSE), has been utilized extensively to probe the local electric field in the active sites of enzymes [1, 2]. For this reason, the electric field and consequent polarization effects induced by a supramolecular host system upon its guest molecules attain special interest due to the implications for various biological processes. Although the host-guest chemistry of crown ether complexes and clathrates is of fundamental importance in supramolecular chemistry, many of these multicomponent systems have yet to be explored in detail using modern techniques [3]. In this direction, the electrostatic features associated with the host-guest interactions in the inclusion complexes of halogenated acetonitriles and formamide with 18-crown-6 host molecules have been analyzed in terms of their experimental charge density distribution. The charge density models provide estimates of the molecular dipole moment enhancements which correlate with the simulated values of dipole moments under electric field. The accurate electron density mapping using the multipole formalism also enable the estimation of the electric field experienced by the guest molecules. The electric field vectors thus obtained were utilized to estimate the vibrational stark effect in the nitrile (-C≡N) and carbonyl (C=O) stretching frequencies of the guest molecules via quantum chemical calculations in gas phase. The results of these calculations indicate remarkable elongation of C≡N and C=O bonds due to the electric fields. The electronic polarization in these covalent bonds induced by the field manifests as notable red shifts in their characteristic vibrational frequencies. These results derived from the charge densities are further supported by FT-IR experiments and thus establish the significance of a phenomenon that could be termed as the "supramolecular Stark effect" in crystal environment.

scholarly journals Does cage quantum delocalisation influence the translation–rotational bound states of molecular hydrogen in clathrate hydrate?

2018 ◽  
Vol 212 ◽  
pp. 533-546 ◽  
Author(s):  
David M. Benoit ◽  
David Lauvergnat ◽  
Yohann Scribano
Keyword(s):  
Molecular Hydrogen ◽  
Bound States ◽  
Clathrate Hydrate ◽  
Guest Molecules

In this study, we examine the effect of a flexible description of the clathrate hydrate framework on the translation–rotation (TR) eigenstates of guest molecules such as molecular hydrogen.

Structural Transition of Trimethylamine Hydrate by Methane or Hydrogen Inclusion

2020 ◽  
Author(s):  
Minjun Cha
Keyword(s):  
Structural Transition ◽  
Guest Molecule ◽  
Clathrate Hydrate ◽  
Hydrogen Gas ◽  
Time Dependent ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Inclusion Process ◽  
Diffraction Patterns

<p>Recently, several alkylamine hydrates have been studied in an effort to reveal the structural transitions from semi- to ‘canonical’ clathrate hydrate in the presence of secondary guest molecules. Trimethylamine (TMA) is known to form the semi-clathrate hydrate, and it has been reported that the structural transition of the TMA semi-clathrate hydrate may not occur in the presence of hydrogen gas as a secondary guest molecule. This paper reports the structural transition of trimethylamine(TMA) hydrate induced by the type of guest molecules. Powder X-ray diffraction patterns of (TMA + H<sub>2</sub>) hydrates show the formation of hexagoanl P6/mmm hydrate, but those of (TMA + CH<sub>4</sub>) hydrates indicate the formation of cubic Fd3m hydrate. Without gaseous guest molecule, the crystal structure of pure TMA hydrate is identified as hexagonal P6/mmm. Therefore, inclusion of gaseous methane in TMA hydrate can induce the structural transition from hexagonal to cubic hydrate or the formation of metastable cubic hydrate. To clearly reveal this possibility, we also check the time-dependent structural patterns of binary (TMA + CH<sub>4</sub>) hydrates from 1 to 14 days, and the results show that the structural transition of TMA hydrate from hexagonal P6/mmm to cubic Fd3m hydrate structure can occur during the methane inclusion process.</p>

Dynamic Behavior of Diatomic Guest Molecules in Clathrate Hydrate Structure II

1997 ◽  
Vol 101 (32) ◽  
pp. 6290-6292 ◽  
Author(s):  
Shinichiro Horikawa ◽  
Hidenosuke Itoh ◽  
Jiro Tabata ◽  
Katsuyuki Kawamura ◽  
Takeo Hondoh
Keyword(s):  
Dynamic Behavior ◽  
Clathrate Hydrate ◽  
Guest Molecules

The Rotational Oscillations of Tetrahydrofuran in Tetrahydrofuran Clathrate Hydrate

1973 ◽  
Vol 51 (24) ◽  
pp. 4062-4071 ◽  
Author(s):  
D. D. Klug ◽  
E. Whalley
Keyword(s):  
Gas Phase ◽  
Low Frequency ◽  
Clathrate Hydrate ◽  
Water Molecules ◽  
Dielectric Measurements ◽  
Effective Dipole Moment ◽  
Orientational Disorder ◽  
Guest Molecules ◽  
Rotational Oscillations ◽  
Good Agreement

The absorptivity of tetrahydrofuran clathrate hydrate in the range 70–7 cm−1 has been measured at several temperatures in the range 17–80 K. There are two broad bands with maxima at 25 and 38 cm−1 which are due to the rotational oscillations of tetrahydrofuran molecules in their cages. The integrated absorptivity yields an effective dipole moment for the oscillation of 1.63 D, which is close to the gas-phase value. The negative second moment of the absorptivity yields the contribution 0.105 ± ~0.007 to the low-frequency refractive index, in good agreement with a less accurate value from dielectric measurements. The orientational disorder of the water molecules causes a distribution of potentials hindering the rotational oscillations of the guest molecules, and a detailed analysis of the shapes of the bands yields directly the distribution of force constants for the oscillations.

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