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Successive Translocation of the Rings in a [3]Rotaxane
Author(s) -
Jagesar Dhiredj C.,
Wiering Piet G.,
Kay Euan R.,
Leigh David A.,
Brouwer Albert M.
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201501162
Subject(s) - rotaxane , chemistry , hydrogen bond , amide , molecule , redox , photochemistry , imide , crystallography , ion , stereochemistry , polymer chemistry , inorganic chemistry , supramolecular chemistry , organic chemistry
A [2]rotaxane, a [3]rotaxane and the corresponding thread containing two succinamide ( succ ) binding stations and a central redox‐active pyromellitimide ( pmi ) station were studied. Infrared spectroelectrochemical experiments revealed the translocation of the macrocycle between the succinamide station and the electrochemically reduced pmi station (radical anion and dianion). Remarkably, in the [3]rotaxane, the rings can be selectively translocated. One‐electron reduction leads to the translocation of one of the two macrocycles from the succinamide to the pyromellitimide station, whereas activation of the shuttle through two‐electron reduction results in the translocation of both macrocycles: the dianion, due to its higher electron density and hence greater hydrogen‐bond accepting affinity, is hydrogen bonded to both macrocycles. Systems with such an on‐command contraction are known as molecular muscles. The relative strengths of the binding between the macrocycle and the imide anions could be estimated from the hydrogen‐bond‐induced shifts in the C=O stretching frequencies of hydrogen‐bond accepting amide groups of the macrocycle.