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A pH‐Sensitive Lasso‐Based Rotaxane Molecular Switch
Author(s) -
Clavel Caroline,
Romuald Camille,
Brabet Emile,
Coutrot Frédéric
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201203597
Subject(s) - rotaxane , moiety , chemistry , molecular machine , deprotonation , molecule , stereochemistry , nuclear magnetic resonance spectroscopy , materials science , nanotechnology , supramolecular chemistry , organic chemistry , ion
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 1 H NMR spectroscopy: the best conditions of self‐entanglement were found in the less polar solvent CD 2 Cl 2 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.