Clathrate hydrates with hydrogen-bonding guests

Buch, V.; Devlin, J. Paul; Monreal, I. Abrrey; Jagoda‐Cwiklik, Barbara; Uras-Aytemiz, Nevin; Ćwiklik, Łukasz

doi:10.1039/b911600c

Cited by 154 publications

(264 citation statements)

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“…Pure ammonia clathrate hydrate synthesis cannot be done by simply cooling aqueous ammonia solutions, as a variety of stoichiometric hydrates of ammonia are known to form preferentially (2,11,18,19). Other ways of forming clathrate hydrates include vapor deposition of water at low temperatures to yield amorphous ice, followed by exposure of the ice to a pressure of guest gas and annealing (29), or vapor codeposition of water and the potential guest material at low temperatures, again, followed by annealing (23,30,31). It has been shown that below approximately 140 K ice surfaces are relatively inert unless strong hydrogen-bond donors or acceptors are present.…”

Section: Resultsmentioning

confidence: 99%

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Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems

Shin

Kumar

Udachin

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

130

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There is interest in the role of ammonia on Saturn's moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons' atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods.ice | single crystal X-ray diffraction | hydrogen bonding | hydrate inhibitors | ethane A mmonia has long been seen as a key species in extraterrestrial space, both interstellar and on outer planets, moons, and comets and the interplay of ammonia, methane, and water has been the subject of a considerable number of studies and speculation (1-8). The main role assigned to ammonia has been that of an antifreeze for ice and clathrate hydrate formation, modifying the stability region of the solid ice and methane clathrate hydrate phases as a thermodynamic inhibitor (2, 5, 9). However, ammonia is a methane-sized molecule, thus based on size alone it has the potential for being a suitable guest for clathrate hydrate cages. Issues that may have prevented ammonia from being considered as a suitable clathrate guest molecule include the notion that guest species need to be hydrophobic in order to be incorporated into clathrates, and the observation of a number of stoichiometric nonclathrate phases of ammonia and water obtained upon cooling aqueous ammonia solutions (2). Previous experimental work on the water-ammonia and water-methaneammonia systems had not shown evidence for the enclathration of ammonia (5,(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Close inspection, however, shows that the low pressure ammonia dihydrate (18) and the high pressure phase II of ammonia monohydrate (19) have structural features in common with canonical clathrate and semiclathrate structures.Recent structural analysis and molecular simulations have shown that some guest molecules which form strong hydrogen bonds with the water framework of the clathrate hydrate lattice may nonetheless produce stable phases (20-23). It is therefore reasonable to consider that ammonia has potential as a clathrate guest molecule. Furthermore, previous experimental and computational studies hav...

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Section: Resultsmentioning

confidence: 99%

“…Recent structural analysis and molecular simulations have shown that some guest molecules which form strong hydrogen bonds with the water framework of the clathrate hydrate lattice may nonetheless produce stable phases (20)(21)(22)(23). It is therefore reasonable to consider that ammonia has potential as a clathrate guest molecule.…”

mentioning

confidence: 99%

Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems

Shin

Kumar

Udachin

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

130

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“…This implies that there is some hostguest interaction, and indeed, hydrogen-bonding is known to occur for a variety of guest molecules in clathrate hydrates, including small ethers. [31][32][33] To explore the possibility of strong radical-host interactions, we performed a DFT calculation on tetrahydrofuran-3-yl (the H isotopomer of 1) at the center of a single cage of 28 water molecules arranged to mimic the 5 12 .) The focus of the present paper is on the identification of guest radicals.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Free Radicals in Clathrate Hydrates of Furan, 2,3-Dihydrofuran, and 2,5-Dihydrofuran by Muon Spin Spectroscopy

et al. 2016

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In addition to their importance as abundant hydrocarbon deposits in nature, clathrate hydrates are being studied as potential media for hydrogen and carbon dioxide storage, and as "nano-reactors" for small molecules. However, little is known about the behaviour of reactive species in such materials. We have employed muon spin spectroscopy to characterize various organic free radicals which reside as isolated guests in structure II clathrates. The radicals are formed by reaction of atomic muonium (Mu) with the guest molecules: furan and two isomeric dihydrofurans. Muonium is essentially a light isotope of hydrogen, and adds to unsaturated molecules in the same manner as H. We have determined muon and proton hyperfine coupling constants for the muoniated radicals formed in the clathrates and also in neat liquids at the same temperature. DFT calculations were used to guide the spectral assignments and distinguish between competing radical products for Mu addition to furan and 2,3-dihydrofuran. Relative signal amplitudes provide yields and thus the relative reactivities of the C4 and C5 addition sites in these molecules. Spectral features, hyperfine constants and reactivities all indicate that the radicals do not tumble freely in the clathrate cages in the same way that they do in liquids.

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“…There have also been recent IR, Raman, and molecular dynamics ͑MD͒ studies of hydrates and evidence of hydrogen-bond formation with the guests has been observed. 16 Unlike ketone and ether guests studied previously, alcohols act as both hydrogen-donors and hydrogen-acceptors in hydrogen bonding with water and both types of bonds are considered and analyzed. The dynamics of the guest motions are studied and correlated with the effects of guest-water hydrogen bonding.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen-bonding alcohol-water interactions in binary ethanol, 1-propanol, and 2-propanol+methane structure II clathrate hydrates

Alavi

Takeya

Ohmura

et al. 2010

The Journal of Chemical Physics

113

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The small alcohols ethanol, 1-propanol, and 2-propanol are miscible in water, form strong hydrogen bonds with water molecules, and are usually known as inhibitors for clathrate hydrate formation. However, in the presence of methane or other help gases, clathrate hydrates of these substances have been synthesized. In this work, molecular dynamics simulations are used to characterize guest-host hydrogen bonding, microscopic structures, and guest dynamics of binary structure II clathrate hydrates of methane (small cages) with ethanol, 1-propanol, and 2-propanol in the temperature range of 100–250 K to gain insight into the stability of these materials. We observe that these alcohols form structures with dynamic long-lived (∼10 ps) guest-host hydrogen bonds in the hydrate phases while maintaining the general cage structure of the sII clathrate hydrate form. The hydroxyl groups of ethanol, 1-propanol, and 2-propanol act as both proton acceptors and proton donors and there is a considerable probability of simultaneous hydrogen bonding between O and H hydroxyl atoms with different cage water molecules. The presence of the nonpolar methane molecule and the hydrophobic moieties of the alcohols stabilize the hydrate phase, despite the strong and prevalent alcohol-water hydrogen bonding. The effect of the alcohol molecules on the structural properties of the hydrate and the effect of guest-host hydrogen bonding on the guest dynamics are studied.

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Clathrate hydrates with hydrogen-bonding guests

Cited by 154 publications

References 58 publications

Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems

Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems

Characterization of Free Radicals in Clathrate Hydrates of Furan, 2,3-Dihydrofuran, and 2,5-Dihydrofuran by Muon Spin Spectroscopy

Hydrogen-bonding alcohol-water interactions in binary ethanol, 1-propanol, and 2-propanol+methane structure II clathrate hydrates

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