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An Anionic Ring Locked into an Anionic Axle: A Metastable Rotaxane with Chemically Activated Electrostatic Stoppers
Author(s) -
LunaIxmatlahua Rubi A.,
CarrascoRuiz Anayeli,
Cervantes Ruy,
Vela Alberto,
Tiburcio Jorge
Publication year - 2019
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.201902735
Subject(s) - rotaxane , cationic polymerization , metastability , axle , dissociation (chemistry) , chemistry , molecule , electrostatics , ring (chemistry) , photochemistry , chemical physics , crystallography , polymer chemistry , supramolecular chemistry , organic chemistry , mechanical engineering , engineering
The use of the electrostatic stoppers concept in the field of mechanically interlocked molecules is reported; these stoppers are chemically sensitive end groups on a linear guest molecule that allows for the conversion of a pseudo ‐rotaxane species into a rotaxane complex by a change in the medium acidity. The chemical stimulus causes the appearance of negative charges on both ends of the linear component, passing from cationic to anionic, and causing a significant ring‐to‐axle electrostatic repulsion. This phenomenon has two different and simultaneous effects: 1) destabilizes the complex as a consequence of confining an anionic ring into an anionic axle, and 2) increases the dissociation energy barrier, thus impeding ring extrusion. This newly formed metastable rotaxane species is resistant to solvent and temperature effects and performs as a two‐state degenerated molecular shuttle in solution.