Coupling of molecular motions through non-bonding interactions: 13C NMR spin–lattice relaxation studies of a host–guest complex
✍ Scribed by Göran Hilmersson; Julius Rebek Jr
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 389 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
13C NMR spinÈlattice relaxation and 13CÈM1HN nuclear Overhauser measurements were performed on the encapsulation complex between [2.2]paracyclophane and a dimeric capsule known as the hydroxy "softball.Ï The data were analyzed using the formalism for an isotropically di †using sphere. The binding constant for the complex is (3.5 ^0.5) ] 103 l mol~1 in at 295 K. The average dipoleÈdipole relaxation time is 0.45 ^0.04 s CDCl 3 for the CH vectors of the encapsulated [2.2]paracyclophane and 0.30 ^0.03 s for the skeleton of the hydroxy "softball.Ï The correlation time for the skeleton of the hydroxy "softballÏ is 2.7 ] 10~10 s. The corresponding correlation time for the encapsulated [2.2]paracyclophane is calculated to be 1.2 ] 10~10 s. This results in an average dynamic coupling constant, s, of 0.47, indicating shape complementarity and correlated motion between the hydroxy "softballÏ and the [2.2]paracyclophane.