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Redox‐Controlled Exchange Bias in a Supramolecular Chain of Fe 4 Single‐Molecule Magnets
Author(s) -
Nava Andrea,
Rigamonti Luca,
Zangrando Ennio,
Sessoli Roberta,
Wernsdorfer Wolfgang,
Cornia Andrea
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201500897
Subject(s) - crystallography , intermolecular force , supramolecular chemistry , chemistry , spins , redox , paramagnetism , magnetization , molecule , electron transfer , materials science , photochemistry , inorganic chemistry , condensed matter physics , physics , crystal structure , magnetic field , organic chemistry , quantum mechanics
Tetrairon(III) single‐molecule magnets [Fe 4 (pPy) 2 (dpm) 6 ] ( 1 ) (H 3 pPy=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 [Fe 4 (pPy) 2 (dpm) 6 ][Ru 2 (OAc) 4 ](BF 4 ) 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.