Molecular dynamics simulations of NMR Lineshape Anisotropy of Guest Molecules within Inclusion Complexes

سال انتشار: 1388
نوع سند: مقاله کنفرانسی
زبان: انگلیسی
مشاهده: 787

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شناسه ملی سند علمی:

ISPTC12_004

تاریخ نمایه سازی: 27 شهریور 1393

چکیده مقاله:

Clathrate hydrates are a class of inclusion compounds composed ofa framework of hydrogen bonded water molecules forming cageswhich encapsulate non-polar guest molecules. Water molecules ofclathrate hydrates are arranged in regular cages in which thehydrogen bonded network satisfies the requirements of the icerules. Depending on the size of the guest species, clathrate hydrateswith different cage sizes and relative numbers of cages are formed.Small guest molecules generally form structure I (sI) clathrates witha the unit cell composed 46 water molecules arranged in six large14-sided cages (51262) with average cavity radii of 4.33 Å and two12-sided cages (512) with average cavity radii of 3.95 Å. The sixlarge cages in the unit cell form three mutually perpendicular pairswhich share a hexagonal side. The large cages in the sI clathrate areflattened in the direction perpendicular to the two hexagonal facesof the cage and non-spherical guest molecules such as CO will bepreferentially aligned with the long axis parallel to the hexagonalfaces. This leads to incomplete averaging of the chemical shifttensor observed in the 13C NMR spectra of the CO guests in thelarge cages of the sI clathrate and nonisotropic lineshapes.

نویسندگان

Hossein Mohammadi-manesh

Department of Chemistry, Isfahan University of Technology, Isfahan, ۸۴۱۵۶-۸۳۱۱۱, Iran.

Saman Alavi

Department of Chemistry, University of Ottawa, Ottawa, Ontario K۱N ۶N۵, Canada

Mahmud Ashrafizaadeh

Department of Mechanical Engineering and Supercomputing Center, Isfahan University of Technology, Isfahan, ۸۴۱۵۶-۸۳۱۱۱, Iran

Bijan Najafi

Department of Chemistry, Isfahan University of Technology, Isfahan, ۸۴۱۵۶-۸۳۱۱۱, Iran.