Structural Changes of a Doubly Spin-Labeled Chemically Driven Molecular Shuttle Probed by PELDOR Spectroscopy.
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.
Dipartimento di Chimica "G. Ciamician", University of Bologna, Via Selmi 2, 40126, Bologna, Italy.
Paola
P
Franchi
Dipartimento di Chimica "G. Ciamician", University of Bologna, Via Selmi 2, 40126, Bologna, Italy.
Valentina
V
Bleve
Dipartimento di Chimica "G. Ciamician", University of Bologna, Via Selmi 2, 40126, Bologna, Italy.
Elisabetta
http://orcid.org/0000-0002-9222-5164
E
Mezzina
Dipartimento di Chimica "G. Ciamician", University of Bologna, Via Selmi 2, 40126, Bologna, Italy.
Christian
C
Schäfer
Dipartimento di Chimica "G. Ciamician", University of Bologna, Via Selmi 2, 40126, Bologna, Italy.
Giulio
http://orcid.org/0000-0002-7183-2985
G
Ragazzon
Dipartimento di Scienze Chimiche, University of Padova, Via Marzolo 1, 35131, Padova, Italy.
Marco
M
Albertini
Dipartimento di Scienze Chimiche, University of Padova, Via Marzolo 1, 35131, Padova, Italy.
Donatella
D
Carbonera
Dipartimento di Chimica "G. Ciamician", University of Bologna, Via Selmi 2, 40126, Bologna, Italy. alberto.credi@unibo.it.|Dipartimento di Scienze e Tecnologie Agro-alimentari, University of Bologna, Viale Fanin 44, 40127, Bologna, Italy. alberto.credi@unibo.it.
Alberto
http://orcid.org/0000-0003-2546-9801
A
Credi
Dipartimento di Scienze Chimiche, University of Padova, Via Marzolo 1, 35131, Padova, Italy. marilena.divalentin@unipd.it.
Marilena
M
Di Valentin
Dipartimento di Chimica "G. Ciamician", University of Bologna, Via Selmi 2, 40126, Bologna, Italy. marco.lucarini@unibo.it.
Marco
http://orcid.org/0000-0002-8978-4707
M
Lucarini
PELDOR spectroscopy; molecular devices; rotaxanes; spin labeling; supramolecular chemistry