Solution and Solvent-Free Stopper Exchange Reactions for the Preparation of Pillar[5]arene-containing [2] and [3]Rotaxanes.

Fiche publication

Date publication

janvier 2024

Journal

Chemistry (Weinheim an der Bergstrasse, Germany)

Auteurs

Membres identifiés du Cancéropôle Est :
Dr CIANFERANI Sarah

Tous les auteurs :
Becharguia N, Nierengarten I, Strub JM, Cianférani S, Rémy M, Wasielewski E, Abidi R, Nierengarten JF

Lien Pubmed

https://www.ncbi.nlm.nih.gov/pubmed/38165139

Résumé

Diamine reagents have been used to functionalize a [2]rotaxane building block bearing an activated pentafluorophenyl ester stopper. Upon a first acylation, an intermediate host-guest complex with a terminal amine function is obtained. Dissociation of the intermediate occurs in solution and acylation of the released axle generates a [2]rotaxane with an elongated axle subunit. In contrast, the corresponding [3]rotaxane can be obtained if the reaction conditions are appropriate to stabilize the inclusion complex of the mono-amine intermediate and the pillar[5]arene. This is the case when the stopper exchange is performed under mechanochemical solvent-free conditions. Alternatively, if the newly introduced terminal amide group is large enough to prevent the dissociation, the second acylation provides exclusively a [3]rotaxane. On the other hand, detailed conformational analysis has been also carried out by variable temperature NMR investigations. A complete understanding of the shuttling motions of the pillar[5]arene subunit along the axles of the rotaxanes reported therein has been achieved with the help of density functional theory calculations.