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Structural Changes of a Doubly Spin‐Labeled Chemically Driven Molecular Shuttle Probed by PELDOR Spectroscopy
Author(s) -
Franchi Paola,
Bleve Valentina,
Mezzina Elisabetta,
Schäfer Christian,
Ragazzon Giulio,
Albertini Marco,
Carbonera Donatella,
Credi Alberto,
Di Valentin Marilena,
Lucarini Marco
Publication year - 2016
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.201601407
Subject(s) - rotaxane , nitroxide mediated radical polymerization , axle , molecular machine , electron paramagnetic resonance , ring (chemistry) , chemistry , resonance (particle physics) , site directed spin labeling , spectroscopy , molecule , nuclear magnetic resonance , crystallography , chemical physics , materials science , nanotechnology , atomic physics , polymer , physics , organic chemistry , supramolecular chemistry , radical polymerization , copolymer , thermodynamics , quantum mechanics
Gaining detailed information on the structural rearrangements associated with stimuli‐induced molecular movements is of utmost importance for understanding the operation of molecular machines. Pulsed electron–electron double resonance (PELDOR) was employed to monitor the geometrical changes arising upon chemical switching of a [2]rotaxane that behaves as an acid–base‐controlled molecular shuttle. To this aim, the rotaxane was endowed with stable nitroxide radical units in both the ring and axle components. The combination of PELDOR data and molecular dynamic calculations indicates that in the investigated rotaxane, the ring displacement along the axle, caused by the addition of a base, does not alter significantly the distance between the nitroxide labels, but it is accompanied by a profound change in the geometry adopted by the macrocycle.