Relative Rotational Motion between -Cyclodextrin Derivatives and a Stiff Axle Molecule
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- 作者：Dai Nishimura ; Tomoya Oshikiri ; Yoshinori Takashima ; Akihito Hashidzume ; Hiroyasu Yamaguchi ; Akira Harada
- 刊名：Journal of Organic Chemistry
- 出版年：2008
- 出版时间：April 4, 2008
- 年：2008
- 卷：73
- 期：7
- 页码：2496 - 2502
- 全文大小：506K
- 年卷期：v.73,no.7(April 4, 2008)
- ISSN：1520-6904
文摘
Novel [2]rotaxanes bearing 
-cyclodextrin (-CD) derivatives and a diphenylacetylene axis moleculewith trinitrobenzene as a bulky stopper have been prepared to investigate the relative rotary movementof a ring relative to an axis molecule and that of an axis molecule in a ring by NMR techniques. [2]Rotaxanes 2 and 3 were composed of -CD derivatives (2: 6-phenyl-amide--CD; 3: 6-stilbene-amide--CD). The protons of -CDs in rotaxanes were thoroughly assigned by the two-dimensional NMRtechniques (TOCSY, COSY, ROESY, HMQC, and HMBC). The protons of -CD in rotaxane 1 did notshow splitting, whereas the resonance peak shifts and splitting for the corresponding protons of -CDderivatives in rotaxanes 2 and 3 were observed by the shielding and deshielding effects from adiphenylacetylene axis molecule. The splitting of resonance peaks was closely related to the rotarymovements of -CDs and an axis molecule. We supposed that -CD in rotaxane 1 rotates freely arounda diphenylacetylene axis molecule, and vice versa, whereas the rotary movement of -CD derivativesand the axis molecules of rotaxanes 2 and 3 were restricted by the steric repulsion between the substituentgroup of -CD and the stopper group of an axis molecule. To estimate the relative rotary movement ofCDs and an axis molecule in rotaxanes, the rotational correlation time (
c) of rotaxanes was measured by13C NMR. The results indicate that the corresponding rotary movement of the modified -CD and theaxis molecules in rotaxanes 2 and 3 depends on the size of the substituent group.
-cyclodextrin (-CD) derivatives and a diphenylacetylene axis moleculewith trinitrobenzene as a bulky stopper have been prepared to investigate the relative rotary movementof a ring relative to an axis molecule and that of an axis molecule in a ring by NMR techniques. [2]Rotaxanes 2 and 3 were composed of -CD derivatives (2: 6-phenyl-amide--CD; 3: 6-stilbene-amide--CD). The protons of -CDs in rotaxanes were thoroughly assigned by the two-dimensional NMRtechniques (TOCSY, COSY, ROESY, HMQC, and HMBC). The protons of -CD in rotaxane 1 did notshow splitting, whereas the resonance peak shifts and splitting for the corresponding protons of -CDderivatives in rotaxanes 2 and 3 were observed by the shielding and deshielding effects from adiphenylacetylene axis molecule. The splitting of resonance peaks was closely related to the rotarymovements of -CDs and an axis molecule. We supposed that -CD in rotaxane 1 rotates freely arounda diphenylacetylene axis molecule, and vice versa, whereas the rotary movement of -CD derivativesand the axis molecules of rotaxanes 2 and 3 were restricted by the steric repulsion between the substituentgroup of -CD and the stopper group of an axis molecule. To estimate the relative rotary movement ofCDs and an axis molecule in rotaxanes, the rotational correlation time (c) of rotaxanes was measured by13C NMR. The results indicate that the corresponding rotary movement of the modified -CD and theaxis molecules in rotaxanes 2 and 3 depends on the size of the substituent group.