title: Redox-Controlled Exchange Bias in a Supramolecular Chain of Fe4 Single-Molecule Magnets.
abstract: Tetrairon(III) single-molecule magnets [Fe4(pPy)2(dpm)6] (1) (H3pPy=2-(hydroxymethyl)-2-(pyridin-4-yl)propane-1,3-diol, Hdpm=dipivaloylmethane) have been deliberately organized into supramolecular chains by reaction with Ru(II)Ru(II) or Ru(II)Ru(III) paddlewheel complexes. The products [Fe4(pPy)2(dpm)6][Ru2(OAc)4](BF4)x with x=0 (2 a) or x=1 (2 b) differ in the electron count on the paramagnetic diruthenium bridges and display hysteresis loops of substantially different shape. Owing to their large easy-plane anisotropy, the s=1 diruthenium(II,II) units in 2 a act as effective s(eff)=0 spins and lead to negligible intrachain communication. By contrast, the mixed-valent bridges (s=3/2, s(eff)=1/2) in 2 b introduce a significant exchange bias, with concomitant enhancement of the remnant magnetization. Our results suggest the possibility to use electron transfer to tune intermolecular communication in redox-responsive arrays of SMMs.
authors.affiliation: Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia & INSTM RU of Modena and Reggio Emilia via G. Campi 183, 41125 Modena (Italy) http://www.corniagroup.unimore.it.|Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, 41125 Modena (Italy).
authors.forename: Andrea
authors.initials: A
authors.lastname: Nava
authors.affiliation: Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia & INSTM RU of Modena and Reggio Emilia via G. Campi 183, 41125 Modena (Italy) http://www.corniagroup.unimore.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Rigamonti
authors.affiliation: Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, 34127 Trieste (Italy).
authors.forename: Ennio
authors.initials: E
authors.lastname: Zangrando
authors.affiliation: Laboratory of Molecular Magnetism (LAMM), Dipartimento di Chimica "Ugo Schiff", Università di Firenze & INSTM RU of Florence, 50019 Sesto Fiorentino (Italy).
authors.forename: Roberta
authors.initials: R
authors.lastname: Sessoli
authors.affiliation: Institut Néel, CNRS, 38042 Grenoble Cedex 9 (France).
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wernsdorfer
authors.affiliation: Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia & INSTM RU of Modena and Reggio Emilia via G. Campi 183, 41125 Modena (Italy) http://www.corniagroup.unimore.it. acornia@unimore.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cornia
keywords: chain structures; iron; magnetic properties; ruthenium; single-molecule magnets