Soi A, Bauer W, Mauser H, Moll C, Hampel F, Hirsch A (1998)
Publication Type: Journal article, Original article
Publication year: 1998
Original Authors: Soi A., Bauer W., Mauser H., Moll C., Hampel F., Hirsch A.
Pages Range: 1471-1478
Journal Issue: 6
URI: https://www.scopus.com/record/display.uri?eid=2-s2.0-0000312024&origin=inward
The conformational and dynamic behaviour of the 25,26,27,28-tetraalkoxycalix[4]arenes 1-7 (R = methyl, propyl) has been investigated by X-ray crystallography, dynamic 1D and 2D NMR spectroscopy, as well as with a series of force field (PIMM) and semiempirical (PM3, MNDO) calculations. The stereo-electronic effects of the upper rim substituents of tetramethoxycalix[4]arenes characteristically influence the preferred arrangement of the phenyl rings in the paco conformation. The in/out isomerisation (0001∼ AAAA⇄0001∼AAAB) taking place in 4 is strongly hindered in 1 due to the smaller diameter of the upper rim. The ease of rotation of the methoxy group attached to the inverted ring in paco-4 can be altered by using a solvent (CDCl), which is able to form a host-guest complex with the calixarene cavity. For 1-3 conelpaco and pacolpaco equilibria have been observed by 2D EXSY spectroscopy. Gibbs activation energies for the cone(C)/cone(C) conversion were determined for 1, 2, 5 and 6. An NMR line shape analysis provided Arrhenius and Eyring activation parameters for the cone(C)/cone(C) conversion in 5 and 6.
APA:
Soi, A., Bauer, W., Mauser, H., Moll, C., Hampel, F., & Hirsch, A. (1998). Investigations on the dynamic properties of 25,26,27,28-tetraalkoxy28-tetraalkoxycalix[4]arenes: Para-substituent- and solvent-dependent properties of paco conformers and determination of thermodynamic parameters of the pinched conelpinched cone conversion. Journal of the Chemical Society, Perkin Transactions 2, 6, 1471-1478.
MLA:
Soi, Antonio, et al. "Investigations on the dynamic properties of 25,26,27,28-tetraalkoxy28-tetraalkoxycalix[4]arenes: Para-substituent- and solvent-dependent properties of paco conformers and determination of thermodynamic parameters of the pinched conelpinched cone conversion." Journal of the Chemical Society, Perkin Transactions 2 6 (1998): 1471-1478.
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