期刊
JOURNAL OF PHYSICAL CHEMISTRY A
卷 114, 期 6, 页码 2338-2343出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp9090602
关键词
-
资金
- University Grants Commission (UGC), New Delhi, India [F34-370/2008(SR)]
- University of Pune
- Council of Scientific and Industrial Research, New Delhi, India
Interactions of sulfur hexafluoride (SF6) with cucurbit[6]uril (CB[6]) have been investigated using the density functional calculations. An encapsulation of guest within CB[6] cavity as well as its binding to either exterior host protons or portal uredio oxygens have been analyzed. The present calculations predict that the complexes with the complete inclusion of SF6 are favored over those possessing lateral or external interactions. The interactions between fluorine and ureido carbons (F---C) of the host contribute to lowering of energy of the complex. Normal mode analyses from the calculated vibrational spectra show a red-shifted stretching (similar to 928 cm(-1)) of S-F bonds perpendicular to the CB[6] cavity axis when SF6 is encapsulated in the host cavity. On the other hand, S-F bonds parallel to the cavity axis exhibit a blue shift as compared to the corresponding vibration of the isolated guest. These frequency shifts of S-F bonds have further been analyzed by mapping the difference electron density on the bond critical point(s) (bcp) in molecular electron density (MED) topography and natural bond orbital (NBO) analyses. A depletion of electron density at the bcp along with an enhanced electron density in antibonding S-F* orbital engender weakening of the bond. Concomitant redistribution of electron density leads to the strengthening of S-F bonds parallel to the cavity axis (directing toward either portals). H-1 NMR reveals that the protons directing toward CB[n] portals are not influenced by encapsulation of the guest, which is in consonant with experimentally measured NMR spectra.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据