Preparation of rotaxanes incorporating a pillar[5]arene subunit

Les rotaxanes constituent un domaine de recherche particulièrement actif en chimie. Dans cette thèse, nous décrivons le potentiel de la stratégie de synthèse développée dans notre groupe pour la synthèse de rotaxanes par des réactions d’échange de bouchons. Nous avons ainsi montré qu’un [2]rotaxane possédant deux bouchons activés peut être mono-fonctionnalisé avec des rendements quasi-quantitatifs. Les dérivés de [2]rotaxanes mono-fonctionnalisés peuvent alors être utilisés pour conduire soit à des [2]rotaxanes, soit à des [3]rotaxanes, suivant la nature de la diamine utilisée. Ces méthodes de synthèse ont alors été utilisées pour la préparation de machines moléculaires. Nous avons montré que la position de macrocycle peut être contrôlée par un stimulus acide-base.Rotaxanes are a particularly active field of research in chemistry. In this thesis we describe the potential of the synthesis strategy developed in our group for the synthesis of new rotaxanes by the stopper exchange method. We have shown that a [2]rotaxane with two activated stoppers can be mono-functionalized in almost quantitative yields. To further explore the potential of mono-functionalized [2]rotaxane derivatives, we then used to give either [2]rotaxanes or [3]rotaxanes, depending on the nature of the diamine used. These synthetic methods were then used to prepare molecular machines. We have shown that the position of the macrocycle can be controlled by an acid-base stimulus

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

International audienceAbstract 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