The Formation of Clathrates

The induction of unconsciousness may be the result of exposure to excessive concentrations of toxic solvents such as carbon tetrachloride or vinyl chloride, as occasionally occurs in industrial situations (solvent narcosis). Also, volatile and nonvolatile anesthetic drugs such as halothane and thiopental, respectively, cause the same physiological effect. The mechanism(s) underlying anesthesia is not fully understood, although various theories have been proposed. Many of these have centered on the correlation between certain physicochemical properties and anesthetic potency. Thus, the oil/water partition coefficient, the ability to reduce surface tension, and the ability to induce the formation of clathrate compounds with water are all correlated with anesthetic potency. It seems that each of these characteristics are all connected to hydrophobicity, and so the site of action may be a hydrophobic region in a membrane or protein. Thus, again, physicochemical properties determine biological activity. 

Despite the formation of clathrate-like clusters and complete 512 cages during these simulations, the increased ordering observed from the radial distribution functions and local phase assignments resulted in the authors concluding that their simulation results are consistent with a local order model of nucleation, and therefore do not support the labile cluster model. 

Nakayama H, Watanabe K (1978) Hydrates of organic compounds. III. The formation of clathrate-like hydrates of tetrabutylammonium dicarboxylates. Bull Chem Soc Jpn 51 2518-2522... 

Crystals of tris(o-phenylenedioxyde)cyclotriphosphazene (97) can act as hosts for the inclusion of a number of organic polymers, e.g. cis-1,4-poly butadiene, 1,4-polyisoprene, polyethylene (PE), poly(ethylene oxide) (PEO) and polytetrahydrofuran. X-ray studies of the PE and PEO inclusion compounds show that the polymer chains are extended along the tunnel-like voids of the host lattice. The formation of clathrates appears to be limited by the tunnel dimension of the host crystal lattice. The melting points of the inclusion adducts appear to be higher than those of either the pure host or the pure... 

The hydrophobic effect is a driving force in the formation of clathrate hydrates and the self-assembly of lipid bilayers. Hydrophobic interactions between lipids and proteins are the most important determinants of biological membrane structure. The three-dimensional folding pattern of proteins is also determined by hydrophobic interactions between nonpolar side chains of amino acid residues. 

Previous works reported on the study of the freezing process of aqueous solutions of ethanol in relation with the phase diagram. They were focused on the identification of different stable or metastable ethanol-hydrate structures using X-ray diffraction and differential scanning calorimetry (DSC). They also mentioned the formation of clathrate hydrates. In spite of the familiarity of alcohol-water systems and their importance in many fields of chemistry, cryobiology, astrophysics, there are still significant discrepancies in the literature with uncertainties concerning the composition and the structure of the stable or metastable eutectic or peritectic hydrates. ... 

The following gas mixtures have been investigated in these studies regarding the formation of clathrate hydrates in presence of a free gas phase. 

An authoritative review on the chemistry of radon, which includes the formation of clathrate compounds, the simple and complex fluorides, ionic radon in solution, redox properties, and the various unsuccessful efforts to prepare an oxide and halides of radon other than the fluoride, was published by the most significant contributor to this field in 1983 (14). 

The Formation of Clathrates Having a Water Host Lattice... 

G. A. Jeffrey, Structural Factors in the Formation of Clathrate Hydrates, Dechema Monograph, 47, 849 (1962). 

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