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Distribution of Butane in the Host Water Cage of Structure II Clathrate Hydrates
Author(s) -
Takeya Satoshi,
Fujihisa Hiroshi,
Hachikubo Akihiro,
Sakagami Hirotoshi,
Gotoh Yoshito
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201403575
Subject(s) - clathrate hydrate , cage , butane , chemistry , hydrate , organic chemistry , engineering , catalysis , structural engineering
Abstract To understand host–guest interactions of hydrocarbon clathrate hydrates, we investigated the crystal structure of simple and binary clathrate hydrates including butane ( n‐ C 4 H 10 or iso ‐C 4 H 10 ) as the guest. Powder X‐ray diffraction (PXRD) analysis using the information on the conformation of C 4 H 10 molecules obtained by molecular dynamics (MD) simulations was performed. It was shown that the guest n‐ C 4 H 10 molecule tends to change to the gauche conformation within host water cages. Any distortion of the large 5 12 6 4 cage and empty 5 12 cage for the simple iso ‐C 4 H 10 hydrate was not detected, and it was revealed that dynamic disorder of iso ‐C 4 H 10 and gauche ‐ n C 4 H 10 were spherically extended within the large 5 12 6 4 cages. It was indicated that structural isomers of hydrocarbon molecules with different van der Waals diameters are enclathrated within water cages in the same way owing to conformational change and dynamic disorder of the molecules. Furthermore, these results show that the method reported herein is applicable to structure analysis of other host–guest materials including guest molecules that could change molecular conformations.