1987 Fiscal Year Final Research Report Summary
The CH/pi Interaction and Related Interactions between Hydrocarbon Groups.
| Project/Area Number |
61430009
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
有機化学一般
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| Research Institution | Yokohama National University |
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Principal Investigator |
HIROTA Minoru Faculty of Engineering, Yokohama National University, 工学部, 教授 (00017881)
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| Co-Investigator(Kenkyū-buntansha) |
SUEZAWA Hiroko Faculty of Engineering, Yokohama National University, 工学部, 教務職員 (30251771)
SAKAKIBARA Kazuhisa Faculty of Engineering, Yokohama National University, 工学部, 助手 (80114966)
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| Project Period (FY) |
1986 – 1987
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| Keywords | The CH / pi interaction / molecular interaction / CH hydrogen bonding / hydrophobic interaction / 疎水基間相互作用 / アルキル芳香族化合物 |
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| Research Abstract |
Experimental evidence in favor of the presence of the attractive interaction between alkyl and pi-electron bearing groups has been accumulated in recent decades. This reseach project started in the aim of elucidating the nature of this sort of interaction and estimating the energy of interaction.
Infrared spectra of a series of isopropyl-2-d (p-substituted Phenyl)-ethyl ketones showed two absorption bands assignable to the free and the CH/pi interacted conformers. The substituent effect on the equilibrium constants and the enthalpy difference between the two conformers determined by infrared spectroscopy were in line with the interpretation that the interaction is hydrogen-bond-like; revealing the fact that the interaction is more favorable when the substituent becomes more electron-donating. Similar results were obtained in the case of intermolecular CH/pi interaction between substituted benzenes and chloroform.
Semi-empirical and ab initio MO calculations on the CH/pi interacted system showed that there is a non-zero overlap between the C-H and the carbon atom bearing pi-electrons. This might be other evidence for the hydrogen-bond-like character of the CH/pi interaction. In contrast, molecular force field calculation on the interacted conformation indicated the important contribution of the dispersive force to its stabilization. In conclusion, the CH/pi interaction is a weak hydrogen bonding in which the dispersive interaction plays a relatively important role.
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