Spectroscopic Signatures of Halogens in Clathrate Hydrate Cages. 1. Bromine

Kerenskaya, Galina; Goldschleger, Ilya U.; Apkarian, and V. Ara; Janda, Kenneth C.

doi:10.1021/jp064523q

Cited by 49 publications

(69 citation statements)

References 39 publications

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“…As discussed earlier for the case of bromine, 7 it is not surprising that halogen molecules interact more strongly with liquid water molecules than with water molecules in the clathrate cage walls. In the clathrate structure, all water molecules are fully hydrogen bonded, so the lone electron pairs on oxygen atoms are not available for interaction with the guest molecule.…”

Section: Uv-vis Spectroscopy As Illustrated Inmentioning

confidence: 66%

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Spectroscopic Signatures of Halogens in Clathrate Hydrate Cages. 2. Iodine

et al. 2007

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UV-vis and Raman spectroscopy were used to study iodine molecules trapped in sII clathrate hydrate structures stabilized by THF, CH 2 Cl 2 , or CHCl 3 . The spectra show that the environment for iodine inside the water cage is significantly less perturbed than either in aqueous solution or in amorphous water-ice. The resonance Raman progression of I 2 in THF clathrate hydrate can be observed up to V ) 6 when excited at 532 nm. The extracted vibrational frequency ω e ) 214 ( 1 cm -1 is the same as that of the free molecule to within experimental error. At the same time, the UV-vis absorption spectrum of I 2 in the sII hydrate exhibits a relatively large, 1440 cm -1 , blue-shift. This is mainly ascribed to the differential solvation of the I 2 electronic states. We conclude that iodine in sII hydrate resides in a 5 12 6 4 cavity, in which the ground-state I 2 potential is not significantly perturbed by the hydrate lattice. In contrast, in water and in ice, the valence absorption band of I 2 is dramatically broadened and blue-shifted by 3000 cm, and the resonance Raman scattering is effectively quenched. These observations are shown to be consistent with a strong interaction between water molecule and iodine through the lone pair of electrons on water as in the case of bromine in the same media. The results presented here, and the stability of other halogen hydrates, were used to test the predictions of simple models and force-field calculations of the host cage-guest association energy.

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Section: Uv-vis Spectroscopy As Illustrated Inmentioning

confidence: 66%

“…7 Two differences are notable: (a) we were not able to prepare clathrate hydrate samples with iodine as the only guest and (b) we have recorded resonance Raman spectra that provide a unique signature of enclathration.…”

Section: Methodsmentioning

confidence: 99%

Spectroscopic Signatures of Halogens in Clathrate Hydrate Cages. 2. Iodine

et al. 2007

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“…As such, the water octamer serves as an ideal testbed for theories and numerical methods for the simulation of more complex systems that contain water. [54][55][56][57][58][59][60][61][62] Despite the relatively small size of the water octamer, its global optimization has proved to be challenging. Stillinger and David 3 report the first optimized structure of the octamer using a model that includes polarization corrections.…”

Section: Introductionmentioning

confidence: 99%

“…The TIP4P model is a four-site model for water, therefore one would anticipate significant differences in the thermodynamic properties when comparing with the SPC model for water. Given the difficulties encountered while trying to resolve which hydrogen bonding arrangement is favored energetically for the real water octamer by potential models, it is highly likely that future simulations of more complicated systems, such as clathrates for example, [54][55][56][57][58][59][60][61][62] will require reproducibility tests of quantitative results with two or more models. The classical heat capacity of the octamer has proved to be sensitive to the details of the potential energy surface.…”

Section: Introductionmentioning

confidence: 99%

The thermodynamic and ground state properties of the TIP4P water octamer

Asare

Musah

Curotto

et al. 2009

The Journal of Chemical Physics

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Several stochastic simulations of the TIP4P ͓W. L. Jorgensen, J. Chandrasekhar, J. D. Madura, R. W. Impey, and M. L. Klein, J. Chem. Phys. 79, 926 ͑1983͔͒ water octamer are performed. Use is made of the stereographic projection path integral and the Green's function stereographic projection diffusion Monte Carlo techniques, recently developed in one of our groups. The importance sampling for the diffusion Monte Carlo algorithm is obtained by optimizing a simple wave function using variational Monte Carlo enhanced with parallel tempering to overcome quasiergodicity problems. The quantum heat capacity of the TIP4P octamer contains a pronounced melting peak at 160 K, about 50 K lower than the classical melting peak. The zero point energy of the TIP4P water octamer is 0.0348Ϯ 0.0002 hartree. By characterizing several large samples of configurations visited by both guided and unguided diffusion walks, we determine that both the TIP4P and the SPC ͓H. J. C. Berendsen, J. P. Postma, W. F. von Gunsteren, and J. Hermans, ͑Intermolecular Forces, Reidel, 1981͒. p. 331͔ octamer have a ground state wave functions predominantly contained within the D 2d basin of attraction. This result contrasts with the structure of the global minimum for the TIP4P potential, which is an S 4 cube. Comparisons of the thermodynamic and ground-state properties are made with the SPC octamer as well.

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“…The clathrate lattice efficiently dissipates the excited electronic state energy of the halogen chromophore through nonradiative channels. The UV-visible and Raman spectra measured Janda et al [65,74,75] clearly show greater perturbations of the spectral properties of the enclathrated halogen guest when the water lattice host cage is smaller than when the lattice host cage is larger. For example, the UV-visible band maximum of the X → C transition of gas phase bromine is 24,270 cm ( Figure 5).…”

Section: Electronic and Vibrational Spectroscopymentioning

confidence: 95%

Clathrate Hydrates

Lee¹,

Kenney²

2018

Solidification

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The clathrate hydrates represent a distinctive, unusual, scientifically significant, and practically important class of solid state materials. Since their discovery in the early nineteenth century, their widespread distribution in oceans and permafrost regions and their ability to trap atoms and small molecules-particularly methane and other small hydrocarbons-has led to the realization that they are simultaneously a tremendous energy source and, in the face of global warming, a potential greenhouse gas release disaster of unprecedented magnitude just waiting to happen. In the twentieth century, it was realized that solid methane clathrate hydrate could plug natural gas pipelines and disrupt oil drilling processes. On the environmental positive side, clathrate hydrates can store hydrogen and sequester carbon dioxide. A brief historical review of the formation, structure, and uses of clathrate hydrates forms the backdrop for a discussion of modern scientific investigations of these solids employing spectroscopy, structure determination methods, isotopic studies, computational-theoretical modeling, and interrogations of guest-host interactions via special guests. For example, the use of colored halogens in clathrate hydrate hosts enables UV-visible spectroscopic methods to be employed to study clathrate hydrate structure.

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Spectroscopic Signatures of Halogens in Clathrate Hydrate Cages. 1. Bromine

Cited by 49 publications

References 39 publications

Spectroscopic Signatures of Halogens in Clathrate Hydrate Cages. 2. Iodine

Spectroscopic Signatures of Halogens in Clathrate Hydrate Cages. 2. Iodine

The thermodynamic and ground state properties of the TIP4P water octamer

Clathrate Hydrates

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