title: Reversible mechanical switching of magnetic interactions in a molecular shuttle.
abstract: Invited for this months cover are the groups of Professors Marco Lucarini and Alberto Credi at the University of Bologna. The cover picture shows coupled and uncoupled states of a [2]rotaxane incorporating stable nitroxide radical units in both the ring and dumbbell components. Interaction between nitroxide radicals could be switched between noncoupled (three-line electron paramagnetic resonance (EPR) spectrum) and coupled (five-line EPR spectrum) upon deprotonation of the rotaxane NH2 (+) centers that effects a quantitative displacement of a dibenzocrown macroring to a 4,4'-bipyridinium recognition site. The complete base- and acid-induced switching cycle of the EPR pattern was repeated several times without an appreciable loss of signal, highlighting the reversibility of the process. Hence, this molecular machine is capable of switching on/off magnetic interactions by chemically driven reversible mechanical effects. For more details, see the Communication on p. 18 ff.
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna Via Selmi 2, 40126 Bologna (Italy).
authors: Valentina
authors: V
authors: Bleve
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna Via Selmi 2, 40126 Bologna (Italy).
authors: Christian
authors: C
authors: Schäfer
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna Via Selmi 2, 40126 Bologna (Italy).
authors: Paola
authors: P
authors: Franchi
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna Via Selmi 2, 40126 Bologna (Italy).
authors: Serena
authors: S
authors: Silvi
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna Via Selmi 2, 40126 Bologna (Italy).
authors: Elisabetta
authors: E
authors: Mezzina
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna Via Selmi 2, 40126 Bologna (Italy).
authors: Alberto
authors: A
authors: Credi
authors: Dipartimento di Chimica "G. Ciamician", Università di Bologna Via Selmi 2, 40126 Bologna (Italy).
authors: Marco
authors: M
authors: Lucarini