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Induction of Motion in a Synthetic Molecular Machine: Effect of Tuning the Driving Force
Author(s) -
Baggerman Jacob,
Haraszkiewicz Natalia,
Wiering Piet G.,
Fioravanti Giulia,
Marcaccio Massimo,
Paolucci Francesco,
Kay Euan R.,
Leigh David A.,
Brouwer Albert M.
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.201204016
Subject(s) - chemistry , ring (chemistry) , imide , acceptor , photochemistry , rotaxane , ion , diimide , hydrogen bond , molecule , polymer chemistry , organic chemistry , physics , supramolecular chemistry , perylene , condensed matter physics
Rotaxane molecular shuttles were studied in which a tetralactam macrocyclic ring moves between a succinamide station and a second station in which the structure is varied. Station 2 in all cases is an aromatic imide, which is a poor hydrogen‐bond acceptor in the neutral form, but a strong one when reduced with one or two electrons. When the charge density on the hydrogen‐bond‐accepting carbonyl groups in station 2 is reduced by changing a naphthalimide into a naphthalene diimide radical anion, the shuttling rate changes only slightly. When station 2 is a pyromellitimide radical anion, however, the shuttling rate is significantly reduced. This implies that the shuttling rate is not only determined by the initial unbinding of the ring from the first station, as previously supposed. An alternative reaction mechanism is proposed in which the ring binds to both stations in the transition state.