The synthesis of a [2]rotaxane, comprising a calix[6]arene-wheel and a dibenzyl-ammonium axle, is here reported. By virtue of its inherent directionality, the calix-wheel makes non-degenerate two equivalent stations of the symmetrical axle. In this way, the neutral rotaxane shows two co-conformations, named endo-alkyl and endo-benzyl, in which an alkyl or benzyl moiety of the axle are included inside the calix-cavity, respectively. NMR and DFT studies showed that the co-conformation preferred by the neutral mechanomolecule is the endo-alkyl' one, which is more stabilized by C-H<bold> interactions between the included alkyl chain and the aromatic wall of the calix</bold>-cavity.[GRAPHICS].
Co-conformational mechanoisomerism in a calix[6]arene-based [2]rotaxane
Talotta, Carmen;De Rosa, Margherita;Soriente, Annunziata;Spinella, Aldo;Gaeta, Carmine;Neri, Placido
2019-01-01
Abstract
The synthesis of a [2]rotaxane, comprising a calix[6]arene-wheel and a dibenzyl-ammonium axle, is here reported. By virtue of its inherent directionality, the calix-wheel makes non-degenerate two equivalent stations of the symmetrical axle. In this way, the neutral rotaxane shows two co-conformations, named endo-alkyl and endo-benzyl, in which an alkyl or benzyl moiety of the axle are included inside the calix-cavity, respectively. NMR and DFT studies showed that the co-conformation preferred by the neutral mechanomolecule is the endo-alkyl' one, which is more stabilized by C-HI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.