A pH‐Sensitive Lasso‐Based Rotaxane Molecular Switch. Issue 9 (23rd January 2013)

• Record Type: Journal Article
• Authors: Clavel, Caroline; Romuald, Camille; Brabet, Emile; Coutrot, Frédéric
• Is Part Of: Chemistry. Volume 19:Issue 9(2013)
• Page Start: 2982
• Page End: 2989
• Publication Date: 2013-01-23
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201203597
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The synthesis of a pH‐sensitive two‐station [1]rotaxane molecular switch by self‐entanglement of a non‐interlocked hermaphrodite molecule, containing an anilinium and triazole moieties, is reported. The anilinium was chosen as the best template for the macrocycle benzometaphenylene[25]crown‐8 (BMP25C8) and allowed the self‐entanglement of the molecule. The equilibrium between the hermaphrodite molecule and the pseudo[1]rotaxane was studied by ¹H NMR spectroscopy: the best conditions of self‐entanglement were found in the less polar solvent CD₂Cl₂ and at high dilution. The triazole moiety was then benzylated to afford a benzyltriazolium moiety, which then played a dual role. On one hand, it acts as a bulky gate to trap the BMP25C8, thus to avoid any self‐disentanglement of the molecular architecture. On another hand, it acts as a second molecular station for the macrocycle. At acidic pH, the BMP25C8 resides around the best anilinium molecular station, displaying the lasso [1]rotaxane in a loosened conformation. The deprotonation of the anilinium molecular station triggers the shuttling of the BMP25C8 around the triazolium moiety, therefore tightening the lasso.</p> </abstract>